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A1.
Baxter, B.P., Brims, M.A. & Taylor, T.B.
Description and Performance of the Optical Fibre Diameter Analyser (OFDA),
IWTO, Nice, Dec 1991 (subsequently published in J. Text. Inst., V83, N4, pp507 - 526, 1992).
Describes the overall OFDA system and its development.
A2.
Baxter, B.P., Brims, M.A. & Taylor, T.B.
Further Studies on the Performance of the OFDA,
IWTO, Punta del Este, April 1992.
Details the results of experiments on OFDA to determine the effects of contamination, operator effects and snippet factors. The results of 1300 comparisons between OFDA and airflow are analysed.
A3.
Baxter, B.P.,
OFDA Round Trials with Greasy Wool Cores,
IWTO, Nice, Dec 1992.
Round trials are described involving 25 core samples of greasy wool, measured on 7 OFDAs in 4 countries. The results allow a more precise estimate of the variance components.
A4.
Baxter, B.P., Brims, M.A.,
Linearity and Focus Independence of the OFDA,
IWTO, Nice, Dec 1992.
Describes experimental work to verify the linearity of OFDA over a 5 to 125m range, and the independence of the result on focus within the normal focus range.
A5.
Baxter, B.P. & Teasdale, D.C.,
Suitability of the Interwoollabs IH tops for Calibration of the OFDA,
IWTO, Nice, Dec 1992.
Describes an investigation to determine whether the use of the Interwoollabs IH calibration tops adds significantly to the differences between OFDA instruments and laboratories. The results show the very small variations found do not add significantly to OFDA measurement variance.
A6.
Turpie, D.W.F., Steenkamp, C.H. & Lupke, E.E., Differences between Calibrations for Wool and Mohair on the FDA 200 and OFDA,
IWTO, Nice, Dec 1992.
Describes experimental work on the FDA200 and OFDA that provides evidence that different calibrations are required for wool and for mohair on both instruments.
A7.
Lupke, E.E., Wright, O.E. & Botes, A.C.,
Comparative study with OFDA and Airflow on Core Samples before and after Shirley Analyser,
IWTO, Nice, Dec 1992.
The OFDA was compared to the Airflow system on 408 core samples, with the OFDA samples being taken both before and after the Shirley Analyser procedure.
A8.
The Optical Fibre Diameter Analyser (OFDA) - New Technology for the Wool Industry,
B.P.Baxter, M.A.Brims & D.C.Teasdale,
Wool Technology & Sheep Breeding, Dec. 1992
A9.
Brims, M.A.,
The Theoretical Comparison of OFDA and FDA class Instruments for the Measurement of Fibre Diameter Distribution,
IWTO, Istanbul, May 1993.
Explains theoretical difference between the measurement of diameter at a point and by averaging over a circular beam, due to fibre curve. 10 Refs.
A10.
Brims, M.A.,
New OFDA Developments and the Use of the OFDA as a Projection Microscope,
IWTO, Istanbul, May 1993.
Provides an overview of use of OFDA as a manual projection microscope. 2 Refs.
A11.
Edmunds, A.R.,
Comparative Fibre Diameter Measurements on N.Z. Wools by Airflow, Laserscan and OFDA,
IWTO, Istanbul, May 1993.
The results of measurements between airflow, Laserscan and OFDA on 2 sets of New Zealand wools are graphed. The total number of samples involved is 140, ranging in diameter from 19um to 40um. 2 Refs.
A12.
Peterson, A.,
Development of the Optical Fibre Diameter Analyser to Measure the Fibre Diameter Profile of Single Wool Fibres,
Misc. publ. 2/94, Dept. Ag., W. Australia, Jan. 1994.
Describes initial results of a software module that allows the OFDA to scan single fibres mounted on a frame that replaces a normal slide. Fibres up to 55mm long may be scanned and a high resolution graph (7um along the fibre) of diameter is obtained.
A13.
Baxter, B.P.,
Review of the Suitability of the 1993 Series of Interwoollabs IH tops for Calibration of the OFDA,
IWTO Technical Report 14, New Delhi, Apr. 1994
Further to [A5], this paper confirms that the 1993 IH tops series is equally suitable for calibration of the OFDA.
A14.
Brims, M. and Peterson, A.,
Measuring Fibre Opacity and Medullation using OFDA - Theory and Experimental Results on Mohair,
IWTO, New Delhi, Apr. 1994.
Describes the optical principle used in the OFDA upgrade to measure fibre opacity and hence medullation of individual fibres. Includes graphs of fibre opacity for cashmere and mohair and a graph of medullation determined by manual projection microscope vs OFDA.
A15.
Baxter, B.P. & Brims M.A.,
1994 Round Trials on Sliver Samples,
IWTO, Nice Dec. 1994.
Reports the results of an international round trial carried out using OFDA and airflow on wool sliver samples. The precision of the OFDA was shown to be similar to airflow.
A16.
Baxter, B.P.,
Supplementary Analyses on OFDA Round Trials on Sliver Samples,
IWTO, Nice Dec. 1994.
A supplementary analysis of the above report to show that 2 slides per sample were adequate to achieve precision rather than the 4 slides used in the trial.
A17.
Baxter, B.P. & Brims M.A.,
1994 Round Trials on Greasy Wool Core Samples,
IWTO, Nice Dec. 1994.
Reports the results of an international round trial carried out using OFDA and airflow on greasy wool core samples. The precision of the OFDA was shown to be similar to airflow.
A18.
Brims M.A.,
Bias in Measured Standard Deviation that would result from Bias in Quoted Mean Diameter of Calibration Standards: Experimental Verification Using OFDA,
IWTO Harrogate, June 1995.
Using recent data from projection microscope (PM) round trials, the effect of short snippet lengths on PM and its subsequent effect on instruments such as OFDA is described. 11 Refs.
A19.
Edmunds, A. R.,
OFDA Measurements of Additional Fibre Parameters: Some Preliminary Results,
IWTO, Harrogate, June 1995.
Describes experimental results using the recent OFDA options for measuring medullation and snippet curvature. A good calibration was obtained for OFDA medullation against PM measurements. Fibre curvature for both wool and mohair was found to increase if the samples are aqueous scoured before measurement. 9 Refs.
A20.
Harig H. ,
Report of the IWTO Round Trial Part 1: Raw Wool,
Report 15, IWTO, Harrogate, June 1995.
Reports on an international round trial comparing airflow, OFDA and Laserscan. Final summary is in A24.
A21.
Baxter B.P. and Marler J.W.
Addendum to Report 15.
Estimates the confidence limits based on Report 15.
A22.
Harig H.,
Report of the IWTO Round Trial Part 2: Wool Tops,
Report 16, IWTO, Harrogate, June 1995.
Reports on an international round trial comparing PM, OFDA and Laserscan. Final summary is in A25.
A23.
Marler J.W. and Baxter B.P.
Addendum to Report 16.
Estimates the confidence limits based on Report 16.
A24.
Harig H.,
Report of the 1995 IWTO Round Trial Part 1: Raw Wool, Additional Remarks and Figures at the Harrogate Meeting,
IWTO, Harrogate, June 1995.
Provides extra graphs and conclusions to A20.
A25.
Harig H.,
Report of the 1995 IWTO Round Trial Part 2: Wool Tops, Additional Remarks and Figures at the Harrogate Meeting,
IWTO, Harrogate, June 1995.
Provides extra graphs and conclusions to A22.
A26.
Smuts S., Schleth A., Hunter L.,
OFDA Measurement of Wool Fibre Crimp - A preliminary Report,
IWTO, Nice 1995.
A group of 25 wool tops, previously measured for crimp and bulk, were measured using the OFDA fibre curve option, and the results graphed. A high correlation was found between OFDA curvature and crimp, and between OFDA curvature and bulk. 6 Refs.
A27.
Van Zyl A.M.
Comparison of Whole slide *1 versus Whole slide *2 for Mean Fibre Diameter and Standard Deviation Using OFDA,
IWTO Raw Wool Group Meeting, Nice, December 1995. Appendix 7.
A28.
Turpie D.W. Steenkamp C.H.,
Objective Measurement of Objectionable Medullated Fibres in Commercial Mohair Tops Using An Optical Fibre Diameter Analyser (OFDA): An Introductory Study,
Report No. 1. IWTO Harrogate, June 1995.
Extensive comparisons between different opacity thresholds on the OFDA were performed against visual counts of objectionable fibres in mohair. A high correlation was found between the visual and OFDA results.
A29.
Turpie D.W.F.,
Report on Round Trial No. 1 of the Working Group on "Objectionable" Medullated Fibres,
IWTO, Special Topics Group, Nice, 1995.
Reports the results of an international round trial involving 8 laboratories measuring 5 wool samples and 5 mohair samples. A good correlation was found between visually objectionable fibres and the OFDA measurement.
A30.
Peterson A.D., Gherardi S.G.,
Measurement of Cashmere Yield and Mean Fibre Diameter using the Optical Fibre Diameter Analyser (OFDA).
Western Australian Department of Agriculture, Baron-Hay Court, South Perth, WA 6151, Australia. 1995.
110 samples were measured for yield using the OFDA and the shirley analyser technique, yielding r^2 of 0.59. Measurements of mean fibre diameter were compared between OFDA and FDA. Concluded that OFDA can be used to measure the yield and diameter of cashmere to an acceptable precision. 20 Refs.
A31.
Lupton, C.J, Minikheim D.L, Pfeiffer F.A., Marschall J.R.
Concurrent Estimation of Cashmere Down Yield and Average Fibre Diameter using The Optical Fibre Diameter Analyser.
Texas Agricultural Experiment Station, Texas A&M University System, 7887 North Highway 87, San Angelo Texas 76901-9782 USA.
Two groups of 75 and 54 cashmere samples were compared for OFDA estimated yield against yield by Shirley Analyser, a correlation of r=0.91 and r=0.85 was found. Mean fibre diameter of down from the original histogram was found to be highly correlated with the mean fibre diameter measured on the down from the Shirley Analyser process. 13 Refs.
A32.
Baxter B.P.
Preliminary Investigations into the Use of OFDA for Estimating Bulk.
IWTO, Capetown Technical Report 13, April 1996
An experiment is described comparing wool samples measured by New Zealand standard NZS 8716 using a WRONZ bulkometer against a bulk estimate derived from a formula using OFDA mean diameter and OFDA fibre curvature. The results show a linear relationship. 2 Refs.
A33.
Lee J.A., Maher A.P., Frampton C.M.A., Ranford S.L
Comparison of Medullation on the Same Fibre Sites using OFDA and Projection Microscope.
IWTO, Capetown Technical Report 14, April 1996
Comparative measurements of medullation were made at the same sites on individual fibres using OFDA and projection microscope. This data was used to explore several aspects of the relationship between OFDA opacity and medullation. 11 Refs.
A34.
Turpie D.W.F.
Report on Confidence Limit Analysis Pertaining to Round Trial No. 1 of the Working Group on "Objectionable" Medullated Fibres.
IWTO Special Topics Group, Appendix 1, April 1996.
Reports the calculated confidence limits on objectionable fibres, flat fibres, total medullation, opacity, s.d. of opacity, m.f.d. of medullated fibres, m.f.d of the samples and s.d of the samples, from the round trial number 1.
A35.
Edmunds A.R.
Spreader Effects on OFDA Fibre Diameter Measurements.
IWTO Raw Wool Group Appendix 5, April 1996.
Reports the experimental comparison of 3 different spreader types and concludes that whilst the differences are small, measurements should be made using the same spreader that was used for calibration. 2 Refs.
A36.
Van Zyl, A.M.
Comparison of Wholeslide*1 Versus Wholeslide*2 for Mean Fibre Diameter and Standard Deviation using OFDA- Part II.
IWTO Raw Wool Group Appendix 4, April 1996.
Complements the results of A27 by repeating the work using the circular spreader and concludes by recommending the OFDA Test Method 47 should be altered to use wholeslide*1 instead of wholeslide*2.
A37.
Baxter B.P.
Analyses of Precision Statistics Arising From the July 1996 Medullation Round Trial.
IWTO Technology and Standards Committee, Report 2, Nice, December 1996.
Data is analysed from the medullation round trial and presented as a table of confidence limits. 3 Refs.
A38.
Turpie D.W.F.
Objectionable Medullated Fibre in Wool & Mohair- Results of Round Trial No. 2, and Comparative Results Obtained by Projection Microscope.
IWTO Technology and Standards Committee, Report 5, Nice, December 1996.
Reports the results of an international round trial involving 8 laboratories and 80 samples including scoured and tops of mohair and wool, based on the OFDA IWTO-DTM-57-96. 3 Refs.
A39.
Edmunds A.R., Summer R.M.W.
Further Data on the Use of OFDA for Estimating Raw Wool Bulk.
IWTO Technology and Standards Committee, Report 7, Nice, December 1996.
A set of 141 NZ wools from 7 breeds of sheep are measured using the NZ Standard Core Bulk Test and also for curvature and diameter by OFDA. A good linear relationship is found between Core Bulk and a linear combination of radius of curvature, mean diameter and SD of diameter. 4 Refs.
A40.
Cottle D.J., Almeida C.D., Baxter P., Petrie D.J. P
Precision of OFDA Fibre Diameter Measurements of Midside Wool Samples.
IWTO Technology and Standards Committee, Report 8, Nice, December 1996.
Reports the results and measured confidence limits of an interlaboratory round trial to be used in the Australian/New Zealand Standard for Wool Fleece Testing and Measurement (DR 96157-96163). 4 Refs.
A41.
Turpie D.W.F.
Report on Results of Round Trial on Relaxation and Some Related Investigations.
IWTO Sliver Group, Appendix 5, Nice, December 1996.
Reports the results of a round trial involving 9 laboratories on the effect of relaxation of top samples on OFDA, Airflow and Projection Microscope. No Refs.
A42.
Baxter B.P.
Preliminary Data on Diameter Distribution Differences between Projection Microscope, OFDA and Laserscan.
IWTO Sliver Group, Appendix 2, Nice, December 1996.
Presents the results on comparisons between diameter distribution data on 3 tops (31.28, 34.31, 37.11) obtained by 3 methods (OFDA, Laserscan, Projection Microscope). OFDA and Laserscan both measured slightly higher SD and CV than projection microscope. 1 Ref.
A43.
Baxter B.P, Cottle D.J.
Fibre Diameter Distribution Characteristics of Midside (Fleece) Samples and Their Use in Sheep Breeding .
IWTO Technology and Standards Committee, Report 12, Boston May 1997.
The relationship between mean fibre diameter and distribution was studied in a total of 100,000 samples from hundreds of flocks. The implications of the relationships are discussed in relation to using these measurements in sheep breeding programs. 20 Refs.
A44.
Edmunds A.R.
Relaxation, Curvature and Snippet Length Effects in Profile Diameter Measurement.
IWTO Technology and Standards Committee, Report 20, Boston May 1997.
OFDA measurements of fibre diameter and radius of curvature have been made on the current set of Interwoollabs Reference Slivers both before and after relaxation by steaming. Two different snippet lengths and full length fibres were used. Recommends a standard relaxation technique should be included in all fibre diameter measurement procedures. 12 Refs.
A45.
Edmunds A.R.
Within-laboratory Precision of OFDA Measurement of Fibre Curvature and Prediction of Bulk.
IWTO Technology and Standards Committee, Report 21, Boston May 1997.
Estimates were made of the within-laboratory precision of the values of fibre curve, radius of curvature and the predicted core bulk obtained using OFDA measurements. Satisfactory precision of predicted core-bulk should be obtained by measuring two slides per sample on the whole slide *1 setting. 5 Refs.
A46.
Brims M.
Along Fibre Diameter and Cleanliness Measurement Using OFDA.
IWTO Technology and Standards Committee, Report 23, Boston May 1997.
Introduces a new OFDA software addition to measure the diameter variation along about 200um of the snippet. From this measurement, the uniformity of the fibre can be determined, and the area of "blobs" such as residual grease is reported as a percentage. 3 Refs.
 

Fibre Measurement

B1.
Blankenburg, G., Philippen, H., Spiegelmacher, P. & Hahnen, J.,
Correlation of the Fibre Ellipticity, Snippet Length and Embedding Medium with the Mean Diameter of Mohair and Wool.,
IWTO, Nice, Dec 1992.
The ellipticity of 6 Interwoolabs and 8 IMA mohair tops are measured, and the results used to explain differences between wool and mohair calibrations, and the snippet length effect in wool calibrations. 6 Refs.
B2.
Edmunds, A.R.,
Effects of Snippet Length on Profile Fibre Diameter Measurements,
IWTO, Nice, Dec 1992
Provides a theoretical discussion on the interaction of ellipticity and snippet length on projected image techniques such as projection microscope and OFDA.. Graphs are included showing the measured mean diameter and standard deviation on OFDA measurements of 10 tops with snippet lengths ranging from 0.2 to 5mm. 9 Refs.
B3.
Baxter, B.P.,
Influences on Comparisons between the Mean Fibre Diameter of Wool measured by Airflow and by Projected Image Methods,
IWTO, Istanbul, May 1993.
Summarises the large volume of work on biases between Airflow and projected image techniques. Covers areas such as specific gravity, crimp, ellipticity, coefficient of variation, calibration errors, grease, fibre length, preparation effects, relaxation, medullation (lambs wool) and nutritional deficiencies. 57 Refs.
B4.
Teasdale, D.C.,
A Technical note on the Bias in Diameter Coefficient of Variation caused by using the average Diameter of Fibre Snippets,
IWTO, Istanbul, May 1993
B5.
Liu, Y. and Baxter, B.P.,
Current Advanced Technologies in Raw Wool Testing,
First China International Wool Conference, Xi'an, P. R. China, Apr. 1994
B6.
Blankenburg, G., Henning, H.J., Spiegelmacher, P., Philippen, H,
Influence of Snippet Length on the Micro projection Diameter Values,
IWTO, New Delhi, Apr. 1994.
Provides a history of trials of the effect of snippet length on projection microscope measurement of fibre diameter, and presents the results of a new international trial on the snippet length effect. 13 Refs.
B7.
Edmunds, A.R.,
Effects of Standard Deviation on Airflow Measurements of Mean Fibre Diameter,
IWTO, Nice, Nov. 1993.
Linear regressions of the standard deviation vs the mean are calculated for all the Interwoollabs calibration wool tops since 1959 and for 228 N.Z. wools. Deviations from these line have important consequences for the use of airflow. 11 Refs.
B8.
Butler K., Dolling M.,
Relating Mean and CV% of Fibre Diameter to Spinning Fineness,
Technical Release, Victorian Institute of Animal Science, Sneydes Rd, Werribee, Victoria, Australia.
Describes the concept of spinning fineness, and the formulae used to calculate it. 6 Refs.
B9.
Hunter L., Gee, E., Braun A.L.
The Effect of Steam or Wet Relaxation on Airflow Wool Fibre Diameter Measurements,
South African Wool and Textile Research Technical Report No. 403. 1978.
Describes an experiment on airflow results on tops that were measured normally and then steamed or soaked in water and re-measured. The wetted (relaxed) tops were found to measure broader on the airflow by up to 0.8um. 2 Refs.
B10.
Smuts S., Hunter L., Gee, E.
The Effect of Medullation and Coefficient of Variation of Diameter on the Airflow Measured Diameter of Mohair, South African Wool and Textile Research Technical Report No. 560.
An experiment involving 83 mohair lots was carried out to determine the effect of medullation and CV of diameter on airflow measured diameter. Medullation was found to have no apparent effect but CV was found to have a significant effect although at about half the level of theoretical predictions. 26 Refs.
B11.
Swan, P.G.
Fibre Specification and Staple Structure,
CSIRO Division of Wool Technology, WoolSpec 94 Report, Sydney, Nov 1994.
Describes the relationship between the wool staple and the fibres within. Presents experimental data that shows resistance to compression can be predicted from fibre diameter and curvature. Also, a strong positive correlation was found between measured fibre curvature (PM) and staple crimp frequency, and a negative correlation between standard deviation of curvature and staple crimp definition. 26 Refs.
B12.
Nissen-Wooller B., Baird K., Marler J.W.,
Mean Fibre Diameter Measurement of Coarse Tops using the Projection Microscope Method - Comparison of Two Snippet Lengths,
IWTO, Nice, Dec 1994.
Reports the results of an interlaboratory trial which compares the PM measurement of 0.8mm snippet length to PM measurement of 2mm snippet length. A statistically significant average decrease of 0.67um was found when the snippet length was increased from 0.8mm to 2mm at the average top diameter of 36.5um, however, the between laboratory component of variance increased at the same time. 13 Refs.
B13.
Baxter B.P.,
Some Observations on the 1993 Snippet Length Effect - Projection Microscope Round Trial.
IWTO Paper 4, Nice, 1994.
Suggests that fibre curvature measurements on the OFDA, together with the results of the round trial, lend support to the theory proposed by Edmunds (B2). 13 Refs.
B14.
Hunter L.,Smuts S., Dorfling L.
The Characterisation and Measurement of Objectionable Medullated Fibres in Wool and Mohair Using Image Analysis.
IWTO Special Topics Group, Appendix 4, Capetown April 1996.
Describes work at the CSIR Division of Textile Technology in South Africa to measure medullation in mohair and its effect on dyeing. Experimental results based on measurement of diameter and medulla diameter ratio on Cape Mohair and carpet wools are reported. 19 Refs.
B15.
Naylor G.R.S., Phillips D.G
Skin Comfort of Wool Fabrics.
IWTO Technology and Standards Committee, Report 7, Boston, May 1997.
Skin comfort was measured for a range of single jersey fabrics made from worsted spun yarn of either wool or acrylic fibres. Relative comfort can be predicted from the density of coarse fibre ends per unit area of fabric, with the percentage of fibre ends greater than 32um being the key factor. 6 Refs.
B16.
Lindsay A.R., Marler J.W.
The Importance of the Coefficient of Variation of Fibre Diameter of Blends of Wool Tops when Measured by Airflow, Laserscan and OFDA.
IWTO Technology and Standards Committee, Report 13, Boston, May 1997.
The measured fibre diameter of blends of wool top was investigated using airflow, Laserscan and OFDA. It was found that if the individual components of the blend differed by more than 10um, the airflow could be in error by up to 4um. Concludes that large differences between airflow and projection microscope techniques may be due to excessively high coefficient of variation of diameter in the sample. 9 Refs.
B17.
Sommerville P.J.
The Effect of between Fibre Coefficient of Variation on the Fibre Fineness Measured by the Airflow.
IWTO Technology and Standards Committee, Report 14, Boston, May 1997.
The development of the theory of the airflow instrument is described, and an experiment is conducted using airflow, Laserscan and OFDA to confirm the theoretical predictions of the effect of coefficient of variation of diameter on the estimates of fineness obtained by airflow. 14 Refs.
B18.
Somerville P.J.
Measurement of the Fineness of Superfine Wool: A comparison of Airflow, Laserscan and OFDA.
IWTO Technology and Standards Committee, Report 15, Boston, May 1997.
In a study of the measurements of mean fibre diameter of fleece samples from superfine sheep, using Airflow, Laserscan and OFDA, significant diameter dependent differences were found between the instruments. Below 16um, OFDA is registering a greater number of fine fibres than Laserscan. 12 Refs.

Diameter and Diameter Distribution Measurement

Baxter, B. P. (1991). Measurement of the mean and distribution of fibre diameter of wool using an image analyser, (first draft). Nice, France, IWTO.

Baxter, B. P., M. A. Brims and T. Taylor (1992). "Description and performance of the Optical Fibre Diameter  Analyser (OFDA)." Journal of the Textile Institute 83(8): 507-526.

            Describes the development and performance of the first commercial version of the OFDA100.

Baxter, B. P., M. A. Brims and T. Taylor (1992). Further studies on the performance of the OFDA. IWTO, Technical report 8, Punta del Este, Uruguay.

            Details a number of studies undertaken with the OFDA100 to characterise its performance and response to possible interfering effects such as sample contamination, operator influences, and snippet-related factors.  Reports the results of 1300 comparisons between OFDA and airflow.  Used to move the test method from a working group draft to a draft test method.

Baxter, B. P. (1992). OFDA round trials with greasy wool cores. IWTO, Technical report 8, Nice, France.

            First international round trial with 25 greasy wool samples and a number of different preparation techniques.  7 instruments were used in 4 countries to allow estimates to be made of variance components for diameter measurement.

Baxter, B. P. and M. A. Brims (1992). Linearity and focus independence of the OFDA. IWTO, Technical report 9, Nice, France.

            Describes experimental work with graticules and precision wires to examine the linearity and focus effects on the OFDA over the range 5 to 125 µm.

Baxter, B. P. and D. C. Teasdale (1992). Suitability of Interwoollabs IH tops for calibration of the OFDA. IWTO, Technical report 10, Nice, France.

            Analyses the performance of OFDA when using IH tops as calibration material, to establish whether this method adds significantly to the overall variance.  It concludes that the use of IH tops provides a satisfactory calibration method.

Baxter, B. P., M. A. Brims and D. C. Teasdale (1992). "The Optical Fibre Diameter Analyser (OFDA) - New technology for the Wool Industry." Wool Technology and Sheep Breeding 15(4): 131-134.

            Description of the OFDA100 technology.

Edmunds, A. R. (1992). Effects of snippet length on profile diameter measurements. IWTO, Nice, France.

            Provides a theoretical relationship between snippet length, ellipticity, and diameter for projected image methods such as projection microscope and OFDA.  Shows plots of mean fibre diameter and standard deviation of diameter determined by OFDA on 10 tops with snippet lengths from 0.2 to 5 mm.

Lüpke, E. E., O. E. Wright and A. C. Botes (1992). Comparative study with OFDA and airflow on core samples before and after Shirley Analyser. IWTO, Nice, France.

            Results from OFDA and airflow were compared on 408 greasy core samples, with the OFDA samples being measured before and after Shirley Analyser treatment.

Turpie, D. W. F., C. H. Steenkamp and E. E. Lüpke (1992). Differences between calibrations for wool and mohair on the FDA200 and OFDA. IWTO, Technical report 2, Nice, France.

            Describes experimental work using FDA200 and OFDA100 instruments that provides evidence that different calibrations are required for wool and mohair on both instruments.

Anon. (1993). Fineness distribution determined by digital image processing. Wool Record: 55.

            Description of the OFDA100 and its capabilities

Brims, M. A. (1993). The theoretical comparison of OFDA and FDA class instruments for the measurement of fibre diameter distribution. IWTO, Istanbul, Turkey.

            Explored the theoretical differences between the measurements of diameter at a point on a fibre snippet as compared with averaging over a length intersected by a circular beam.

Edmunds, A. R. (1993). Comparative fibre diameter measurements on NZ wools by airflow, Laserscan and OFDA. IWTO, Istanbul, Turkey.

            Details the results of comparisons between measurements on two sets of NZ wools using airflow, OFDA and Laserscan.  140 samples were used ranging from 19 to 40 µm.  The work suggests that calibration methods need to reflect measurement preparation methods.

Edmunds, A. R. (1993). A comparative evaluation of the Sirolan Laserscan and OFDA for fibre diameter measurement of New Zealand wools. Christchurch, New Zealand, WRONZ: 27.

            Describes the results of measurements on 3 sets of greasy wool samples (comprising 50, 90 and 13 samples respectively) on both OFDA and Laserscan, using both minicores of greasy wool (cleaned in trichloroethane), and minicores of Waring Blendor-prepared samples.  Measurements were compared against known airflow values.  Some difficulties were experienced with operation and calibration of the Laserscan.  The author concluded that "especially for use on New Zealand wools, OFDA is the preferable system of the two for the measurement of fibre diameter."

Teasdale, D. C. (1993). A technical note on the bias in diameter coefficient of variation caused by the average diameter of fibre snippets. IWTO, Instanbul, Turkey.

            Examines the effects on coefficient of variation of using fibre diameter measurements undertaken at a point compared with diameter measurement based on an average over a small length of snippet.  The difference, due to an additional component of variation along the snippet length, accounts for some of the observed differences between OFDA and Laserscan diameter distribution statistics.

Baxter, B. P. (1994). "Influences on the comparisons between the mean fibre diameter of wools measured by airflow and by projected image methods." Wool Technology and Sheep Breeding 42(2): 176-193.

            Literature review of performance and technical issues concerned with the different physical principles used by each of the diameter measurement techniques.  Covers a wide range of possible interfering effects, such as fibre specific gravity, crimp, ellipticity, coefficient of variation, calibration errors, residual grease, snippet and specimen fibre length, preparation effects, relaxation, medullation, and animal nutritional influences.

Baxter, B. P. (1994). Review of the suitability of the 1993 series of Interwoollabs IH tops for calibration of the OFDA. IWTO, Technical report 14, New Delhi, India.

            Reviews the calibration performance of the OFDA using the 1993 IH tops series, and confirms that this series is equally as capable of providing suitable calibrations as the previous series.

Baxter, B. P. (1994). Some observations on the 1993 snippet length effect - projection microscope round trial. IWTO, Technical report 4, Nice, France.

            Applies OFDA measurements of curvature and Edmunds's elliptic integral theory to the 1993 snippet length round trial results, and concludes that the data is consistent with this theory

Baxter, B. P. and M. A. Brims (1994). 1994 OFDA round trials on greasy wool core samples. IWTO, Technical report 5, Nice, France.

            Outcome of an international round trial using greasy wool cores measured for mean fibre diameter by both OFDA100 and airflow.  The precision of the OFDA100 and airflow were found to be similar.

Baxter, B. P. and M. A. Brims (1994). 1994 OFDA round trials on sliver samples. IWTO, Technical report 6, Nice, France.

            Reports the results of an international round trial carried out using OFDA and airflow on sliver samples and concludes that the precision of the OFDA was similar to that of airflow.

Baxter, B. P. (1994). Supplementary analyses on OFDA round trial on sliver samples. IWTO, Nice, France.

            A supplementary analysis of the data from the 1994 sliver round trial.  The author concluded that 2 slides per sample were adequate to achieve the required precision, rather than the 4 slides used in the trial.

Edmunds, A. R. (1994). Effects of snippet length on profile fibre diameter measurements: additional data for recent series of Interwoollabs reference tops. IWTO, Technical report 14, Nice, France.

            Repeats investigations using OFDA100 measurements on a range of snippet lengths (see report 14, IWTO Nice, Dec 1992) on 17 additional IH tops.  Concludes that the available evidence clearly indicates that the snippet length used in all profile fibre diameter measurements should be at least 2.0 mm in order to avoid serious positive bias in both mean and standard deviation.  The author also recommends that snippets should be obtained by minicoring rather than microtoming.

Edmunds, A. R. (1994). Comments on snippet length effects. IWTO, Annex to technical committee minutes, New Delhi, India.

            Comments separately on recent contributions by Blankenburg and David concerning the snippet length effect and trials, and adds further data obtained using the OFDA100 on the 1991/2 and 1993 series of IH tops.  Both minicored and microtomed snippets were measured with snippet lengths ranging from 0.2 to 4.5 mm.  The author concludes that all fibre diameter values reported in the past have been positively biased.

Houillon, L. (1994). Mesure du diametre des fibres. Industrie Textile: 31-34.

            In reference to the IWTO test methods for OFDA and Laserscan, or any other methods based on distribution data, the author proposes a new calibration method ("Mephisto") based on full feedback of the distribution data to the instrument. (In French)

Qi, K., C. J. Lupton, F. A. Pfeiffer, et al. (1994). "Evaluation of the Optical Fibre Diameter Analyser (OFDA) for measuring fiber diameter parameters of sheep and goats." Journal of Animal Science 72: 1675-1679.

            Experiments were conducted on both wool and mohair in top, core and staple forms, in which the results obtained with the OFDA100 were compared with both the FDA200 and the ASTM projection microscope method.  The authors concluded that the OFDA results were very closely related to the PM measurements, with the OFDA overcoming one of the shortcomings of the FDA200, which is over-estimation of SD.  They suggest that the OFDA is a promising system for rapid and accurate evaluation of fiber diameter and its distribution.

Wear, J. L. (1994). An investigation into the relationship between spin fineness, OFDA MFD, SD, and airflow measurement. Wellington, NZ, SGS-WTS.

            Airflow, OFDA MFD and SD, and OFDA spinning fineness were investigated to establish whether airflow could be predicted from these OFDA measurements.  Whilst the use of SD and OFDA MFD improved the prediction of airflow over the use of MFD alone, use of spinning fineness did not improve the correlation.

Anon. (1995). Digital image processing for the determination of fiber fineness and fineness distribution. Melliand Textilberichte: E83-E84, 311-314.

            Describes the instrument and parameters measured by the OFDA100 - fibre diameter, diameter distribution (histogram), standard deviation, coefficient of variation, and prickle factor

Baxter, B. P. and J. W. Marler (1995). Report of the 1995 IWTO round trial: Part 2: Wool tops - Addendum: Confidence limits for measurements made on tops. IWTO, Technical report 16 addendum, Harrogate, UK.

            Analysis of precision statistics of the 1995 IWTO round trial on tops

Brims, M. A. (1995). Bias in measuring standard deviation that would result from bias in quoted mean fibre diameter of calibration standards: experimental verification using OFDA. IWTO, Technical report 14, Harrogate, UK.

            Using recent data from projection microscope round trials, the author describes the effects that measuring short snippet lengths on projection microscope would have on the subsequent calibration and measurements on instruments such as OFDA.

Harig, H. (1995). Report of the IWTO round trial part 1: raw wool. IWTO, Technical report 15, Harrogate, UK.

            Reports on an international round trial to compare mean fibre diameter and diameter distribution results on OFDA, Laserscan and airflow on greasy wool cores.

Harig, H. (1995). Report of the IWTO round trial part 2: wool tops. IWTO, Technical report 16, Harrogate, UK.

            Reports on an international round trial comparing mean fibre diameter and diameter distribution from projection microscope, airflow, OFDA and Laserscan on tops.

Harig, H. (1995). Report of the 1995 IWTO round trials: Raw wool, additional remarks and figures. IWTO, Harrogate, UK.

            Provides plots and conclusions additional to the original report, and concludes that OFDA and Laserscan have similar performance on raw wool.

Harig, H. (1995). Report of the 1995 IWTO round trials: Wool tops, additional remarks and figures. IWTO, Harrogate, UK.

            Provides additional plots and conclusions to the original report.

IWTO (1995). IWTO-47: Measurement of the mean and distribution of fibre diameter of wool using an Optical Fibre Diameter Analyser (OFDA). Ilkley, IWTO.

            Method for the measurement of fibre diameter and diameter distribution of wool using OFDA.  Applies to fibres in raw wool and in sliver/top.

Marler, J. W. and B. P. Baxter (1995). Report of the 1995 IWTO round trial: Part 1: Raw wool - Addendum: Confidence limits for measurements made on raw wool. IWTO, Technical report 15, Addendum, Harrogate, UK.

            Analysis of precision statistics for the 1995 IWTO round trial on greasy wool

van Zyle, A. (1995). Comparison of 'Wholeslide x 1' versus 'Wholeslide x 2' for mean fibre diameter and standard deviation using OFDA. IWTO, Raw wool group Appendix 7, Nice, France.

            Concludes that 'wholeslide x 1' is adequate to provide the required precision.  This work was carried out using the WTB design of spreader.

 

Baxter, B. P. and A. van Zyle (1996). Preliminary data on diameter distribution differences between projection microscope, OFDA and Laserscan. IWTO, Sliver group, tabled report, Nice, France.

            Presents the results of histogram comparisons between diameter distribution data on 3 coarse tops obtained by OFDA100, Laserscan and projection microscope.  The OFDA and Laserscan both reported higher SD and CvD than the projection microscope.

Edmunds, A. R. (1996). Spreader effects on OFDA fibre diameter measurements. IWTO, Raw wool group, Appendix 5, Capetown, South Africa.

            Reports an experimental comparison of three different spreader designs and concludes that whilst the differences between the results were small, measurements should be made with the same design as was used for calibration.

Edmunds, A. R. and S. L. Ranford (1996). Update to precision in IWTO-47 (OFDA). IWTO, Raw wool group Appendix 7, Nice, France.

            Examines changes in measurement variance due to change from 'wholeslide x 2' to 'wholeslide x 1'.

Herrmann, S. and F.-J. Wortmann (1996). Results of the EFFN round trial on cashmere diameter testing. European Fine Fibre Network Occassional Publication 4. Aberdeen, Scotland, EFFN, Macauley Land Use Research Institute: 117-133.

            An interlaboratory trial was carried out using cashmere samples at various stages of dehairing.  Projection microscope was used in 8 laboratories, OFDA100 in 3 laboratories, and Laserscan and Cross Section Method in one each.  Concludes that the OFDA should be the preferred measurement technique for diameter of cashmere.

Turpie, D. W. F. (1996). Report on results of round trial on relaxation and some related investigations. IWTO, Sliver group, Appendix 5, Nice, France.

            Reports the results of a round trial involving 9 laboratories on the effects of relaxation on OFDA100, projection microscope and airflow measurements of mean fibre diameter.  Relaxation methods included hot soaking as well as steaming.

Turpie, D. W. F. and C. H. Steenkamp (1996). Changes in dimensions of calibration sample snippets with changes in pre-treatment. IWTO, Technical report 16, Capetown, S. Africa.

            Examines the effects of soaking tops in hot water and detergent on the measurement of diameter by OFDA100.  The work confirms the necessity of calibrating the instrument for the preparation conditions under which it will be used for measurement, as is specified in the test method IWTO-47.

van Zyle, A. (1996). Comparison of 'wholeslide x 1' versus 'wholeslide x 2' for mean fibre diameter and standard deviation using OFDA - Part II. IWTO, Raw wool group, Appendix 4, Capetown, South Africa.

            Complements earlier work, by using the circular spreader, and concludes by recommending a change to IWTO-47 to require 'wholeslide x 1' rather than 'wholeslide x 2' measurement.

Baxter, B. P. (1997). "Examination of the differences between OFDA and Laserscan on ultrafine wools." Wool Technology and Sheep Breeding 45(4): 267.

            Compares the MFD results for wools of 18 microns and below on both the OFDA100 and Laserscan, and drew attention to the increasingly significant divergence between the methods as the diameter decreased.  By comparing results with projection microscope data, it was concluded that the OFDA was measuring correctly, and that the Laserscan was in error due to extrapolation effects in the calibration.  A pragmatic solution was offered to correct the Laserscan calibration by using alternative curve-fitting methods.

Blankenburg, G., J. Hahnen, K.-H. Lehmann, et al. (1997). The problem: Fibre "diameter" measurement in profile. IWTO, Sliver group Appendix 1, Nice, France.

            Presents data on "wet/set" and "wet relaxed" tops to support the hypothesis that "by a wet relaxation process the curvature and or rotation of the major/minor axes along fibre length is increased, and by this increasing the probability to measure in profile a "diameter value" which is closer to the "apparent diameter" as without relaxation"

Edmunds, A. R. (1997). Relaxation, curvature and snippet length effects in profile diameter measurement. IWTO, Technical report 20, Boston, USA.

            OFDA measurements of fibre diameter and radius of curvature were made on the then current set of IH calibration tops both before and after relaxation by steaming.  Two different snippet lengths were used as well as full-length fibres.  Recommends that a standard relaxation technique should be included in all fibre diameter measurement procedures.

Hoffmann, R. and J. Vogelsang (1997). Commercial implications of difference in topmaking and top trading (short version). IWTO, Fineness seminar, Boston, USA.

            Reports commercial results of MFD comparisons between the three diameter measurement technologies on tops, and comments on the effective differences in core-comb relationships when the raw wool is measured on airflow and the tops on OFDA or Laserscan.  At the fine end the two new technologies give bigger core-comb differences than airflow.  On tops all three technologies give similar results, but with the airflow being finer at the fine end.  During QC measurements, OFDA and Laserscan agree with each other "nearly perfectly" on tops.  Similar average values are reported for CvD from OFDA and Laserscan over 4 diameter ranges.  Hercosett treatment of wool gives coarser airflow results, finer OFDA results, and no change to Laserscan results.  Conditioning of samples is required for both OFDA and Laserscan.  Spinning is affected by both MFD and diameter variation.

Lindsay, A. R. and J. W. Marler (1997). "The importance of coefficient of variation of fibre diameter of blends of wool tops when measured by airflow, Laserscan and OFDA." Wool Technology and Sheep Breeding 47(4): 291-301.

            The measured fibre diameter of blends of wool top was investigated using airflow, Laserscan and OFDA.  It was found that if the individual components of the blend differed by more than 10 µm, the airflow could be in error by up to 4 µm.  The authors conclude that large differences between airflow and projection microscope techniques may be due to excessively high coefficient of variation of diameter in the sample.

Sommerville, P. J. (1997). Measurement of the fineness of superfine wool: a comparison of airflow, Laserscan and OFDA. IWTO, Technical report 15, Boston, USA.

            In a study of the measurements of mean fibre diameter of fleece samples from superfine sheep using airflow, Laserscan and OFDA, significant diameter-dependent differences were found between the instruments, which tended to increase as the diameter was reduced.  Below 16 µm, it was observed that OFDA was measuring a greater number of fine fibres than Laserscan.

van Zyle, A. (1997). Alternative procedures for the handling of subsamples for OFDA - IWTO-47. IWTO, Raw wool group, Appendix 6, Nice, France.

            An experiment is reported in which subsamples are prepared for OFDA measurement in the same way as for airflow in IWTO-28.  It is concluded that there were no significant differences in the results, thereby allowing streamlined preparation procedures to be used.

Baxter, B. P. (1998). An initial investigation into the effects of medullation on comparisons between Airflow, OFDA and Laserscan. IWTO, Technical report 16, Dresden, Germany.

            Using measurements obtained with the medullation module on the OFDA100, a method of correcting for the effects of medullation was suggested, so that OFDA results could be used to predict airflow results on coarser wools.

Baxter, B. P. (1998). Comparison of Laserscan, OFDA and airflow on raw wool samples. IWTO, Raw wool group, Nice, France.

            Results were shown of approximately 370 comparisons between OFDA100, airflow, and Laserscan on a typical range of New Zealand wools.  It was proposed that if the OFDA was operated over the same calibration range as the Laserscan (e.g. 0 to 80 µm), then the degree of agreement between them was exemplary. Similarly, if the same constraint is applied, and an additional adjustment made for the along-fibre variance, the two instruments also agreed on CVD.  On curvature, the level of agreement was again considered satisfactory, although a bias was detected.   It was demonstrated that the Laserscan and airflow give similar results, and that the OFDA and airflow relationship can be improved to the extent that airflow can be satisfactorily predicted.

Baxter, B. P. (1998). Additional comments on the measurement of superfine wools by OFDA, airflow and Laserscan. IWTO, Raw wool group, Nice, France.

            This report followed from a trial carried out between OFDA100, Laserscan and airflow on a broad range of NZ wools, and reported separately.  It highlighted the diameter range below 20 µm, and confirms that the three instruments can now produce consistent results for MFD down to the range covered by the current IH tops.  Good agreement between Laserscan and OFDA was also demonstrated on CvD.  Below 16.5 µm the OFDA diverged from both the airflow and Laserscan on MFD.  Hypotheses were presented that suggested that whilst the instrument was not in error, it was measuring aspects of the fibre which may not be observed by the other instruments, and in that respect there remains a fundamental problem at that extreme end of the range.  Two options were suggested for further investigation

Edmunds, A. R. (1998). Relaxation and snippet length effects on the 12th series of IH tops. IWTO, Raw wool group report RWG06, Nice, France.

            Reports measurements of snippets under normal conditions and after relaxation, and with different snippet lengths. The author concludes that calibration of the OFDA using shorter snippets as specified in the projection microscope method would allow closer agreement between the OFDA and PM on sliver for SD when using 2mm snippets, but would give finer results for MFD.  For curvature measurements, the author notes that steaming appears to cause less relaxation than laboratory scouring.

Knowles, D. G., P. R. Greatorex and G. V. Barker (1998). Comparison of IWTO test methods for fibre diameter measurement of the New Zealand wool clip.  Part 1 - Mean fibre diameter. IWTO, Technical report 12, Dresden, Germany.

            Compares test results on NZ greasy wools using airflow, OFDA and Laserscan in NZWTA's laboratory.

Knowles, D. G., P. R. Greatorex and G. V. Barker (1998). Comparison of IWTO test methods for fibre diameter measurement of the New Zealand wool clip.  Part 2 - Fibre diameter variability. IWTO, Technical report 13, Dresden, Germany.

            Compares the results of OFDA and Laserscan for SD and CvD over a range of NZ wools tested by NZWTA.

Knowles, D. G. (1998). Investigation into mean fibre diameter instrument differences in the measurement of New Zealand superfine wool. IWTO, Technical report 14, Dresden, Germany.

            119 sale lots are compared by all 3 diameter measurement technologies in the NZWTA laboratory.

Marler, J. W. and H. Harig (1998). A comparison of diameter measurement technologies from interwoollab international round trials for wool tops. IWTO, Technical report 10, Dresden, Germany.

            The Interwoollabs round trial data was used to compare the 4 diameter measurement technologies.  Some of the observed differences between airflow and the other methods were found to be related to CvD.  When this was taken into account there were still differences that might be related to medullation content.  The OFDA and Laserscan showed the least variation between methods on paired comparisons.  PM, OFDA and Laserscan showed some systematic differences in SD values.

Pinto de Andrade, L., J. Varzea Rodrigues and J. Serrano (1998). "The quality of fine wool in Portugal - preliminary results." EFFN news 4: 2-5.

            The preliminary results presented show that more than 35% of the wool produced in Portugal, from 1.3 m animals classed as Merino, can be classed as fine wool with a fibre diameter less than 22.5 µm when measured with the OFDA100.

Puntila, M.-L. (1998). "Breeding program for wool traits - The Fine Finnwool Project." EFFN news 4: 14-15.

            Describes the beginning of performance recording for Finnsheep, based on OFDA measurements and BLUP evaluation.

Sommerville, P. J. (1998). Measurement of the fineness of superfine wool: Effect of the revised Laserscan calibration function on comparisons between airflow, Laserscan and OFDA. IWTO, Commercial technology forum paper CTF04, Nice, France.

            Following the use of the new calibration function for the Laserscan, relationships between the diameter measurement systems have been re-examined for superfine wool fleeces.  The Laserscan was now coarser than the airflow in the 15.5 to 19 µm range, and finer than airflow below 15.5 µm.  The Laserscan is now more closely aligned with the OFDA100 for wools below 16 µm.  Previously large differences between OFDA and Laserscan on diameter distribution parameters have been significantly reduced.

Baxter, B. P. (1999). The effects of calibration errors on between-laboratory and between-instrument diameter comparisons. IWTO, Sliver group report 1, Nice, France.

            Examined the Interwoollabs data on laboratory performance in blind trials immediately after calibration.  It concluded that whilst the performance of laboratories using OFDA100 and Laserscan was better than for airflow, there was still a considerable range of possible combinations of bias between different laboratories.  It was proposed that the calibration MSE criteria in the test methods should be reviewed with a view to tightening up the allowable performance

Denney, S. I., T. J. Mahar and J. W. Marler (1999). OFDA measurements using two different snippet lengths (0.8mm and 2.0mm). IWTO, Raw wool group report RWG02, Nice, France.

            Compared the results for MFD, SD, and curvature for 0.8 mm and 2 mm snippets on the OFDA when using the WTB spreader.

Edmunds, A. R. and S. L. Ranford (1999). Conditioning effects on fibre diameter and curvature of the 12th series of IH tops. IWTO, Raw wool group report RWG03, Nice, France.

            Compares the behaviour of IH tops under increasing RH values from 0 to 100% both "as-is" and after relaxation by steaming.  Reports results of OFDA100 mean fibre diameter and curvature.  Confirmed that the behaviour with respect to relative humidity was consistent with previously published data obtained using projection microscope and airflow.

Knowles, D. G. and J. W. Marler (1999). The relationship between mean fibre diameter measurements by airflow, Laserscan and OFDA for Australian and New Zealand wools. IWTO, Raw wool group report RWG02, Florence, Italy.

            Proposes baremes to convert from one measurement result to another for Australian and New Zealand wools.  Based on AWTA and NZWTA data only.

Marler, J. W., G. R. Shepherd and R. G. Barry (1999). A comparison of histograms from OFDA, projection microscope and Laserscan for wool tops. IWTO, Sliver group report SG01, Florence, Italy.

            Uses Interwoollabs PM data on 9 tops to draw comparisons with OFDA100 and Laserscan results obtained in one laboratory.  Very good agreement was obtained in the middle of the diameter range but there were some significant differences evident at both extremes.  The authors comment that the different definitions of diameter used by each instrument are unlikely to mean that the observed differences can be reconciled.  However, they also conclude that the differences are small and unlikely to have any impact on processing or product performance.

Glass, M. (1999?). "A technique for generating random fibre diameter profiles using a constrained random walk." (in draft).

            A random walk technique, using appropriate statistical properties of adjacent points in along-fibre diameter profiles, in conjunction with a constrained walk deviation, has been developed for generating random along-fibre wool snippet diameter profiles.  The technique finds use in Monte Carlo simulations where the variation in diameter along fibres plays a significant role in properties of interest.  Confirms agreement with data published on along-fibre variability measured using OFDA100.

ASTM (2000). ASTM D6500 Standard test method for diameter of wool and other animal fiber using an Optical Fibre Diameter Analyser. Pennsylvania, USA, ASTM.

            Test method for the use of OFDA for the determination of the average fibre diameter and the fibre diameter variation in wool and other animal fibres in their various forms.

Denney, S. I. (2000). Slide preparation procedures for the OFDA - the balance between minicoring and spreading time. IWTO, Raw wool group Appendix 2, Nice, France.

            Examines small biases that could arise due with different spreader designs and length of time the spreader operates for, and recommends text changes to standardise this aspect in IWTO-47

Denney, G. D., T. J. Mahar and J. W. Marler (2000). The effect of snippet length and fibre relaxation on the mean fibre diameter, fibre diameter distribution and fibre curvature measured by Laserscan and OFDA. IWTO, Sliver group report SG03, Christchurch, New Zealand.

            Study of the effects of snippet length and relaxation effects on measurement results from Laserscan and OFDA100.  The results from both instruments were confirmed to be affected by changes in snippet lengths.  The OFDA showed greater differences due to relaxation effects (as is well known, and compensated for in MFD measurement by the calibration process for greasy wool).  The Laserscan was also found to be affected by fibre relaxation, but the potential bias of 0.2 µm was considered by the authors to be "commercially unimportant".

ILRT (2000). The effect of fibre relaxation on the mean fibre diameter and fibre diameter distribution measured by Laserscan and OFDA. IWTO, Sliver group report SG04, Christchurch, New Zealand.

            Examines two different relaxation procedures and the effects on MFD and SD measurement by OFDA100 and Laserscan.  The authors conclude that the effects on Laserscan measurements were small, and the effects on OFDA MFD measurements are compensated for in the calibration process, but that there remained an uncompensated effect on OFDA SD when measuring greasy wool.  (The plots which accompany the paper, however,  suggest that there is a small but significant systematic effect on Laserscan measurements caused by relaxation.)

Knowles, D. G. (2000). The effects of standardising the measurement range on the mean and standard deviation of fineness for Laserscan and OFDA. IWTO, Raw wool group report RWG02, Christchurch, New Zealand.

            Because of the data transmission limitations of some wool industry systems, the report recommends that the number of 1 µm bins reported from both Laserscan and OFDA be standardised to the lowest common denominator of the Laserscan (i.e. 80).  The author concludes that for Australasian fine wools there would be only a small average change in results.  Individual wool samples could show differences of up to 0.3 and 0.9 µm in mean fibre diameter and standard deviation respectively.  No investigation is reported on the possible effects on coarse wools from other sources or for other animal fibres.

Knowles, D. G. (2000). The relationship between coretest fineness measurements by airflow, Laserscan and OFDA of New Zealand merino wool classed at NZPAC. IWTO, Raw wool group report RWG04, Christchurch, New Zealand.

            Compares the results on airflow, OFDA and Laserscan for 362 lots processed at NZPAC.  At less than 15.5 µm the Laserscan and OFDA produce similar results, both measuring finer than airflow.  The opposite trend was shown above 20 µm where airflow measured approximately 0.2 µm finer than the other 2 instruments.

McLaughlin, I. (2000). Innovative wool testing - OFDA, Australian Wool Taskforce 2000.

            Description of the OFDA technology and the application of OFDA2000 to in-shed testing.

Sommerville, P. J. (2000). "Introduction of the Sirolan-Laserscan as the standard service for certification of mean fibre diameter by AWTA Ltd." Wool Technology and Sheep Breeding 48(3): 198-232.

            The paper reviews the development of the projection microscope, the airflow, the Sirolan-Laserscan and the OFDA.  The precision of the instruments is discussed and the differences in the measurements that they provide are reviewed in detail.  The review shows that for Australian greasy wools, the differences between the instruments, while in some cases statistically significant, are generally quite small.  These differences, where they exist, can often be attributed to deficiencies in the airflow instrument.

Standards_Australia and N. Z. Standards (2000). AS/NZS 4492 Wool - fleece testing and measurement, Standards Australia.

            Specifies methods for sampling of individual animals for ranking purposes, and details suitable methods for measuring washing yield and mean fibre diameter.

Stobart, R. H. and A. McColl (2000). A comparison of fiber measurement methods to obtain average fiber diameter of fibers other than wool. IWTO, Commercial technology forum paper CTF04, Christchurch, New Zealand.

            Reports a trial on wool, mohair, cashmere and camel hair, comprising both greasy and top forms, using OFDA, Laserscan and ASTM projection microscope methods.  The authors conclude that there is good concensus amongst the 3 methods for measuring fibers in addition to wool and that these instruments are capable of providing reliable diameter estimates of other fibres.  The individual differences between OFDA and Laserscan for all the samples fell in a consistent band between -0.5 and + 0.5 µm across the diameter range

van Zyle, A. (2000). The relationships between mean fibre diameter measurements by airflow, OFDA and Laserscan for South African wools from different breeds. IWTO, Raw wool group report RWG05, Christchurch, New Zealand.

            Diameter differences between airflow, OFDA and Laserscan on 434 greasy South African wools were found to vary with the breed of sheep.   For the bulk of the SA clip, consisting of merino fleece wool, there appears to be no difference on average between airflow and OFDA.  Mutton merino wool, above 25 µm, which is known to have varying levels of medullation, gives slightly finer results on airflow than on OFDA.

van Zyle, A. (2000). The relationship between airflow and OFDA measurements from South African greasy wool and commercial mill tops. IWTO, Sliver group report SG02, Christchurch, New Zealand.

            For the better quality tops, good relationships with small predicted difference in MFD were found between airflow results of South African greasy wool and the airflow and OFDA results from processed tops.  Between 20 and 26 µm the maximum average predicted difference was 0.1 µm.  Inferior tops produced more variable results.

AWTA (2001). What are the limits to wool fibre fineness measurement. AWTA Ltd Newsletter: 14-15.

            Discusses IWTO Shanghai report RWG 02 and the issue of ultrafine fibres in wool samples with respect to instrument performance, and highlights that both OFDA and Laserscan are operating in areas where calibration must be significantly extrapolated.

Baxter, B. P. (2001). Technical note: 5 micron fibres found in an ultrafine grower lot - implications for diameter distribution measurement. IWTO, Raw wool group report 2, Shanghai, China.

            Historically there has been debate in IWTO Technology and Standards groups about whether ultrafine fibres reported in diameter distributions by the OFDA instrument do actually exist.  This note describes measurements made on electron microscopes in Christchurch, New Zealand, and Aachen, Germany.  These confirmed that fibres, on which valid 5 µm OFDA measurements could be made, do in fact exist in some specialty grower lots.  Such measurements do not, however, necessarily mean that fibres with a continuous diameter of 5 µm are likely to be found frequently
Alternative Uses for OFDA Technology

Brims, M. A. (1993). New OFDA developments and the use of the OFDA as a projection microscope. IWTO, Istanbul, Turkey.

            An overview to the use of special software that allows the OFDA to be used like a projection microscope.

 

Brims, M. A. and A. D. Peterson (1994). Measuring fibre opacity and medullation using OFDA - theory and experimental results on mohair. IWTO, Technical report 21, New Delhi, India.

            Describes the optical principles used in the OFDA100 upgrade to measure fibre opacity and hence medullation of individual fibres.  The paper included graphs of fibre opacity for cashmere and mohair and a comparison of medullation determined by projection microscope and by OFDA.

 

Peterson, A. D. (1994). Development of the Optical Fibre Diameter Analyser to measure the fibre diameter profile of single wool fibres. Perth, West Australia, Department of Agriculture.

            Describes the initial results of a software module that allows the OFDA100 to scan single fibres mounted on a frame that replaces the normal glass slide.  Fibres up to 55 mm in length may be scanned and a high resolution graph of diameter at 7 µm intervals along the fibre can be obtained.

 

Peterson, A. D., S. G. Gherardi and M. A. Brims (1994). "The measurement of medullation in mohair using the Optical Fibre Diameter Analyser." Proc. Aust. Soc. Anim. Prod. 20: 363.

            Briefly describes work carried out to compare projection microscope and OFDA100 measurements of medullation and gare in mohair.  Results indicate that whilst medullation can be repeatably measured by OFDA, further work is required on the measurement of kemp.

 

Edmunds, A. R. (1995). OFDA measurements of additional fibre parameters: some preliminary results. IWTO, Technical report 19, Harrogate, UK.

            Describes experimental results obtained using the OFDA100 upgrades for measuring medullation and fibre curvature.  Good correspondence was obtained between measurements of medullation on OFDA and with the projection microscope.  Fibre curvature was found to increase if the samples were aqueous-scoured prior to measurement.

 

Lupton, C. J., D. L. Minikheim, F. A. Pfeiffer, et al. (1995). Concurrent estimation of cashmere down yield and average fibre diameter using the Optical Fibre Diameter Analyser. 9th International Wool Textile Research Conference, 2, Biella, Italy.

            Two groups of 75 and 54 cashmere samples were compared for OFDA100 estimated yield against yield determined using the Shirley Analyser, and correlation coefficients ( R²) of 0.83 and 0.72 were found.  Mean fibre diameter of down from the original histogram was found to be highly correlated with the mean fibre diameter measured on the down from the Shirley analyser process.

 

Peterson, A. D. and S. G. Gherardi (1995). "Measurement of cashmere yield and mean fibre diameter using the Optical Fibre Diameter Analyser (OFDA)." Australian Journal of Experimental Agriculture 36: 429-435.

            110 samples were measured for yield using both the OFDA100 and the conventional Shirley Analyser methods.  The relationship between the two sets of results yielded an R² of 0.59.  Measurements of mean fibre diameter were compared between the OFDA and an FDA instrument.  It was concluded that the OFDA was capable of measuring cashmere yield and diameter to an acceptable precision.

 

Peterson, A. D. and S. G. Gherardi (1995). Using the Optical Fibre Diameter Analyser to measure medullation in mohair. 9th International Wool Textile Research Conference, 4, Biella, Italy.

            Percentage gare, kemp, and non-medullated fibres as measured by the OFDA100 (2000 counts) were compared with measurements made with the projection microscope using 400 and 800 fibres.  There was good agreement for the percentage of medullated fibres in the range from 2 to 15% when 800 fibres were measured on the PM, but the agreement for kemp was poor.

 

Smuts, S., A. Schleth and L. Hunter (1995). OFDA measurement of wool fibre crimp - a preliminary report. IWTO, Special topics group, Nice, France.

            25 wool tops, previously measured for staple crimp and bulk, were measured using the OFDA100 fibre curve option.  A high correlation was found between OFDA curvature and staple crimp, and between OFDA curvature and bulk.

 

Turpie, D. W. F. and C. H. Steenkamp (1995). Objective measurement of objectionable medullated fibres in commercial mohair tops using an Optical Fibre Diameter Analyser (OFDA): An introductory study. IWTO, Technical report 1, Harrogate, UK.

            Extensive comparisons were shown between counts obtained under different opacity thresholds on the OFDA100 against visual counts of objectionable fibres in mohair.  A high correlation was found between visual and OFDA results.

 

Turpie, D. W. F. (1995). Report on round trial No. 1 of the working group on "Objectionable medullated fibres". IWTO, Special topics group, Nice 1995.

            Reports the results of an international round trial involving 8 laboratories measuring 5 wool samples and 5 mohair samples.  Good correlation was found between visually objectionable fibres and their measurement using OFDA100.

 

Baxter, B. P. (1996). Preliminary investigations into the use of OFDA for estimating bulk. IWTO, Technical report 13, Capetown, South Africa.

            Describes the first investigations into using OFDA diameter and curvature to estimate bulk.  A linear relationship was demonstrated between predicted bulk and values measured by the NZS 8716 bulk test method.

 

Baxter, B. P. (1996). Analyses of precision statistics arising from the July 1996 medullation round trial. IWTO, Technical report 2, Nice, France.

            Analyses all the round trial data in order to provide comprehensive statistics on the precision of the IWTO-57 (OFDA medullation) test method.  It was found that the precision values were effectively similar for all of the assessed count-based parameters at each level of that parameter.

 

Brims, M. A. (1996). Measurement and calibration of opacity using OFDA. IWTO, Capetown, South Africa.

            Explains the methods used to calibrate OFDA100 instruments for opacity, and examines alternatives.

 

Cottle, D. J., C. D. Almeida, B. P. Baxter, et al. (1996). "Precision of OFDA fibre diameter measurements of midside wool samples." Wool Technology and Sheep Breeding 44(4): 295-302.

            Study of the precision of OFDA measurements of midside fleece samples.  Reports 95% confidence limits of ± 0.6 µm for mean fibre diameter and ± 0.4 µm for standard deviation.  Intended to provide preliminary data to be used in the joint Australia - NZ standard for fleece testing.

 

Edmunds, A. R. and R. M. W. Sumner (1996). Further data on the use of OFDA for estimating raw wool bulk. IWTO, Technical report 7, Nice, France.

            141 NZ wools from 7 breeds of sheep were measured using the NZ standard test method for bulk, NZS 8716, and for curvature and diameter using the OFDA100.  Good correlation was found between core bulk and a linear combination of radius of curvature, mean fibre diameter, and SD of diameter.

 

Hunter, L., S. Smuts and L. Dorfling (1996). The characterisation and measurement of objectionable medullated fibres in wool and mohair using image analysis. IWTO, Special topics group, Appendix 4, Capetown, South Africa.

            Describes work at the CSIR Division of Textile Technology to measure medullation in mohair and its effects on dying.  Experimental results based on the measurement of diameter and medulla diameter ratio on Cape mohair and carpet wools were reported, together with results of assessments of objectionable fibre counts.

 

Lee, J. A., A. P. Maher, C. M. A. Frampton, et al. (1996). Comparison of medullation on the same fibre sites using OFDA and projection microscope. IWTO, Technical report 14, Capetown, South Africa.

            Comparative measurements of medullation were made at the same sites on individual fibres using both OFDA100 and the projection microscope.  The data was used to explore several aspects of the relationship between OFDA opacity and medullation.

 

Turpie, D. W. F. (1996). Report on confidence limit analysis pertaining to round trial No. 1 of the working group on 'Objectionable medullated fibres'. IWTO, Special topics group, Appendix 1, Capetown, South Africa.

            Using the first round trial data, reports the calculated confidence limits for OFDA100 measurement of objectionable fibres, flat fibres, total medullation, opacity, SD of opacity, mfd of medullated fibres, as well as MFD and SD of the sample.

 

Turpie, D. W. F. (1996). Objectionable medullated fibre in wool and mohair - Results of round trial No. 2 and comparative results obtained by projection microscope. IWTO, Technical report 5, Nice, France.

            Reports the results of an international round trial based on IWTO-DTM-57 involving 8 laboratories and 80 samples of scoured wool and mohair as well as tops.  The author concludes that the OFDA100 presents a rapid, practical and cost-effective method for estimating both objectionable fibres and total medullation, which correlated at levels of 90% and 92% respectively with ASTM measurements of kemp and total medullation.

 

Anon. (1997). A preliminary study of fibre curvature measurement using Sirolan-Laserscan and its potential applications. Laserscan News: 3-7.

            Describes the measurement of curvature using the Laserscan fibre optic discriminator, and relates the measurements to OFDA100 curvature measurements; resistance to compression results; and to the differences between measured and TEAM predicted hauteur, and to % error in evenness predicted by YarnSpec.

 

Brims, M. A. (1997). Along-fibre diameter and cleanliness measurement using OFDA. IWTO, Technical report 23, Boston, USA.

            Introduces a new OFDA100 software upgrade that allows the instrument to measure diameter variation along approximately 0.2 mm of individual snippets.  From these measurements, the uniformity of the fibre can be determined, and the area of blobs such as residual grease can be reported as a percentage.

 

Edmunds, A. R. (1997). Within-laboratory precision of OFDA measurement of fibre curvature and prediction of bulk. IWTO, Technical report 21, Boston, USA.

            Estimates were made of the within-laboratory precision of the values of mean fibre curvature, radius of curvature, and predicted core bulk obtained using OFDA100 measurements.  It concluded that satisfactory precision could be obtained for estimating core bulk by measuring 2 slides per sample on 'wholeslide x 1' setting.

 

Edmunds, A. R. (1997). "Measurement of fibre curvature: A review of work to date." Wool Technology and Sheep Breeding 45(3): 227-234.

            Reviews work carried out up to 1997 on the measurement of fibre curvature.

 

Greatorex, P. R., D. G. Knowles and G. V. Barker (1997). Evaluation of alternative methods for fibre curvature measurement of New Zealand Wools. IWTO, Technical report 18, Nice, France.

            A strong relationship was found between fibre curvature values measured by OFDA100 and Laserscan, and an adequate relationship was found between curvature and bulk, although no attempt was made to incorporate diameter into the model.

 

IWTO (1997). IWTO-57: Determination of objectionable medullated fibre content of wool and mohair samples by opacity measurements using an OFDA. Ilkley, IWTO.

           

Lobb, J. T., K. A. Hansford, W. Humphries, et al. (1997). A preliminary study of fibre curvature measurement using Sirolan-Laserscan and its potential applications. IWTO, Technical report 8, Boston, USA.

            Reports a preliminary investigation into the validity and application of fibre curvature measurements using Laserscan.  The results are compared with measurements of curvature undertaken with the OFDA100, and the authors conclude (on the basis of a correlation coefficient of 0.91) that the measurements are in "good agreement" (although the measurement units used were different).

 

Lupton, C. J. (1997). Further medullated fiber measurements on selected maohair samples from round trial 2. IWTO, Medullation working group Annex 1, Boston, USA.

            Reports data comparing OFDA100 medullation and kemp measurements with ASTM method D2968, using 10,000 fibers in the latter.  The results show excellent correlation between the two sets of measurements, with correlation coefficients of 0.994 and 0.970 respectively for ASTM 'kemp' versus OFDA 'opacity > 94%', and ASTM 'total medullated fibres' versus OFDA 'total medullated fibres'.

 

Maher, A. P. (1997). OFDA measurements of opacity on medullated fibres: precision estimates from the first round trial. IWTO, Medullation working group Annex 2, Boston.

            Analyses the outcome of a round trial to determine the precision of medullation measurement using the OFDA, and concludes that there is little benefit in measuring each slide more than once, or from measuring more than two slides per sample.

 

Wear, J. L. and B. P. Baxter (1997). Investigation into the relationship between contamination parameters measured by the OFDA and IWTO-10 measurements on commercially-scoured Australiasian wool. IWTO, technical report 4, Nice, France.

            Used the OFDA "blob" parameters (along-fibre aspherities) to develop a regression relationship used to predict the residual grease measurement performed using IWTO-10.  The within-laboratory precision of the predicted residual grease was similar to that of IWTO-10, giving QC laboratories an ideal tool to monitor fibre cleanliness.

 

Baxter, B. P. (1998). "Preliminary results on using the OFDA to discriminate between wool, cashmere, and mohair." Wool Technology and Sheep Breeding 46(1): 24.

            Using a combination of along-fibre parameters available from the OFDA100, statistical methods were compared with reference to their ability to automatically discriminate between wool, mohair and cashmere samples.  In this paper, very good success was reported in discriminating between wool and mohair, and an algorithm was developed which could be used to estimate blend proportions to within ± 10%.

 

Baxter, B. P. (1998). Some notes on the influence of colour on the measurement of medullation by OFDA. IWTO, Sliver group, Nice, France.

            Examined the results of medullation measurements by the OFDA when coloured fibres were present, and suggested a restrictive clause be placed in IWTO-57

 

Baxter, B. P. (1998). Continued investigation of the use of OFDA for fibre type differentiation. IWTO, Special topics group, Nice, France.

            This paper describes continuing work on the use of multivariate analytical techniques on parameters reported by the OFDA100 instrument.  This paper deals with wool and cashmere and confirms that differentiation is feasible for these two fibres.  It was demonstrated that statistical techniques such as neural networks could be used for blend analyses, and suggested that an accuracy of ± 10% would be feasible.  It concluded, however, that more data would be required before blend analysis could be carried out to a level of precision that is likely to be required.  The techniques already outlined were, however, considered suitable for screening pure cashmere from pure wool or heavily adulterated mixes.

 

Lobb, J. T., W. Humphries and G. J. Higgerson (1998). Fibre curvature measurement using Sirolan Laserscan and OFDA. IWTO, Raw wool group report RWG07, Nice, France.

            Describes a trial in which sampling technique (snippet length and cutting method) is investigated and shown to affect the curvature results from both Laserscan, OFDA, and a specially-designed CSIRO automated image analysis system.  Confirms that the 2 mm guillotining and 2 mm minicoring techniques produce comparable curvature relationships to other sampling regimes.  There was a linear correlation close to equivalence between the CSIRO instrument and OFDA for all sampling regimes, but especially on the longer snippets (2mm).  There was a curved relationship between the CSIRO instrument and the Laserscan raw curve measurements, and also between OFDA and Laserscan.  The relationships obtained between the 3 instruments for curvature were compared with previously-published relationships between OFDA and Laserscan.  The authors propose a theoretical relationship (IWTO Boston report 8) to convert Laserscan raw measurements to units of º/mm.

 

Lupton, C. J. and F. A. Pfeiffer (1998). "Measurement of medullation in wool and mohair using an Optical Fibre Diameter Analyser." Journal of Animal Science 76: 1261-1266.

            Three experiments were conducted to compare OFDA100 and PM values of medullation, kemp, and total medullated fibre on wool and Angora mohair.  Whilst an initial experiment showed poor correlation between the two instruments, subsequent work using a wider range of medullation values showed r² values of 0.98, 0.93 and 0.97 respectively between the OFDA and PM values.  It was also found that increasing the total number of fibres counted in the PM work also substantially improved the correlation between values from the two instruments.  The two sets of linear regression equations, for wool and for mohair, had different coefficients, but it was concluded that the OFDA is capable of providing relatively fast, accurate and potentially less expensive estimates of medullated fibre characteristics in mohair and wool.

 

Maher, A. P. and J. S. Daly (1998). "The derivation of the cross-sectional area along wool fibres from the OFDA diameter measurements." Journal of the Textile Institute 89(1): 133-141.

            A unique and theoretically sound method for deriving cross-sectional area along wool fibres is developed, based on OFDA diameter measurements whilst the fibre is rotated.  Diameter values are derived from an equation based on an ellipse whose parameters are the semi-major and semi-minor axes and the angle of rotation of the ellipse.  These parameters are used directly to calculate the cross-sectional area at intervals of approximately 3.2 µm along the length of fibres, to produce a profile at a resolution previously unattained in work reported in the relevant literature.  A unique 3 dimensional representation of the wool fibre was produced, demonstrating spiraling and dramatic variations in cross-sectional area along relatively short sections of the fibre.

 

Maher, A. P., B. D. Cassidy and J. A. Lee (1998). The measurement of medullation percent by volume of wool using an OFDA. IWTO, Technical report 19, Dresden, Germany.

            Compared three methods of calculating percent of medullation by volume from the OFDA100 measurements of medullation by number, and proposed that an exponential transformation gave the best precision and accuracy for this parameter.

 

Peterson, A. D., A. Brims, M. A. Brims, et al. (1998). "Measuring the diameter profile of single wool fibres by using the single fibre analyser (SIFAN)." Journal of the Textile Institute 89(Part 1, No. 3): 441-448.

            Describes an instrument called the Single Fibre Analyser (SIFAN) designed to measure the diameter profile of single wool fibres at very small intervals along its length.  The instrument is able to scan a 100mm long fibre at 40 µm intervals in less than 2 minutes.  The measurement error (se = 0.6 µm) is considered low in view of the relatively large variation in diameter found over relatively short lengths of fibre.  Fibre diameter-length profiles measured using SIFAN were compared with and found to be correlated closely with single fibre and 2mm snippet profiles measured with the OFDA100.

 

Wang, X., L. Chang and L. Wang (1998). Predicting fibre strength variation from fibre diameter variation. 2nd China International Wool Textile Conference, Xi'an, China.

            Single wool fibre diameter and strength were measured on a single fibre analyser (SIFAN).  The CvD was then used to predict the Cv of single fibre strength (breaking load).  The results indicate that coefficient of variation of minimum fibre diameters can accurately predict the coefficient of variation of single fibre strength.  The relationship is not as strong if the Cv of mean single fibre diameter is used.

 

Wang, L. and X. Wang (1998). "Diameter and strength distributions of merino wool in early stage processing." Textile Research Journal 68(2): 87-93.

            Investigation of fibre diameter and strength distributions in early stage processing.  Fibre diameter conforms to a lognormal distribution, and this conformity persists through early stage processing.  Single fibre strength also conforms to a lognormal distribution in general, but the conformity may be distorted by fibre damage in processes such as carding.  The authors propose a formula to estimate the coefficient of variation of single fibre strength from the coefficient of variation of fibre diameter.

 

Drieling, A., R. Baumer, J. Mussig, et al. (1999). "Testing strength, fineness and length of bast fibres." Technische Textilien.

            Reports that airflow is too variable for determining the diameter of bast fibres that vary in respect of fibre type and degree of retting.  OFDA100 gives both diameter and diameter distribution data which compare favourably with other methods and also are reproducible.

Fish, V. E., T. J. Mahar and B. J. Crook (1999). "Fibre curvature morphology and measurement." Wool Technology and Sheep Breeding 47(4): 248-265.

            The report discussed the definition of fibre curvature, and some of the processing and measurement factors that affect the results.  The authors indicate strong correlation between measurements of curvature using OFDA and Laserscan.  They suggest that a calibration method will be required before the measurement can be standardised.  In view of the sensitivity of the measurement to fibre condition and preparation, they caution the use of these measurements prior to agreement of test methods.  47 Refs.

Glass, M. (1999). "The diameter dependence of fibre medullation and the medullation weighting function." (in draft).

            The concept of a medullation weighting function is introduced as a means of describing the variation in fibre medullation with fibre diameter.  Developed principally as an aid to model wool fibre diameter distributions containing medullated fibres, the medullation weighting function may find wider applicability in the classification of animal fibres.  Refers to data obtained with the OFDA100.

Lupton, C. J., F. A. Pfeiffer and A. R. Dooling (1999). "Prediction of cashmere style using objective fiber measurements." Sheep and Goat Research Journal 15(1): 1-4.

            The authors used measurements of cashmere down yield, MFD, down and guard hair staple lengths, and average fibre curvature measurements in multiple linear regression models to predict cashmere style score.  Fibre curvature measured by OFDA was found to be the best single objectively measured trait for predicting cashmere style score.

Madeley, T. and R. Postle (1999). "Physical properties and processing of fine merino lamb's wool.  Part 3: Effects of wool fiber curvature on the handle of flannel woven from woolen spun yarn." Textile Research Journal 69(8): 576-582.

            In woollen system processing, a reduction in fibre crimp/curvature results in greater sliver bulk, more even slubbing, hairier yarns, and loftier knitted fabric.  A subjective and objective evaluation of knitted and woven fabrics processed from batches combining specially selected individual fleeces illustrates how fabric handle can be engineered through the principal raw wool parameters of fibre curvature and diameter.

Bill, M. (2000). Experience with OFDA. 7th PMC Symposium.

            The author describes EMS Chemie's experience with the OFDA100 for determining crimp and count on artificial fibres, and concludes that the instrument gives superior performance to methods previously used.

Brims, M. A. and H. Hornik (2000). Rapid image processing for measuring fibre characteristics. International Fibre Journal: 63-65.

            Describes how the OFDA, widely used in measuring animal fibres, can be applied to the measurement of chemical fibres

Dorfling, L., S. Smuts and L. Hunter (2000). Measuring and characterising objectionable medullated fibres in mohair. 10th International Wool Textile Research Conference, Poster session SF-P1, Aachen, Germany.

            The authors report on the distinguishing features of two groups of medullated fibres ("objectionable" and "non-objectionable") and methods of measurement, using the OFDA100, image analysis, projection microscope and medullameter.

Fish, V. E., T. J. Mahar and B. J. Crook (2000). The influence of preparation techniques on the measurement of fibre curvature. IWTO, Commercial technology forum paper CTF06, Christchurch, New Zealand.

            The authors conclude that the following all have an influence on curvature results: minicored mass, repeatedly minicoring the same mass, and the state of sharpness of the minicore tubes.  Extended conditioning time was found to have no effect.

Lupton, C. J., D. F. Waldron and F. A. Pfeiffer (2000). Prickle factor in fleeces of performance-tested fine-wool rams. San Angelo, Texas, Texas Agricultural Experiment Station: 103-110.

            Fibre diameter distributions were measured in 3 consecutive years using an OFDA100 on core samples of unskirted fleeces from 524 fine-wool rams completing a central performance test.  MFD, SD and CvD were also measured on britch and midside samples.  The prickle factor, SD, and CvD did not differ among years.  The authors derived a regression equation to predict prickle factor from MFD, SD and CvD, and concluded that since 92% of the variability in PF was accounted for by MFD and CvD, it was not necessary to include PF in selection index equations.

van Rensburg, B. (2000). "Fibre curvature: overview and evaluation for South African wools using OFDA and Laserscan." Wool Technology and Sheep Breeding 48(3): 233-252.

            OFDA and Laserscan were used to measure fibre curvature on IH tops and South African core samples.  It was concluded that using "wholeslide x 1" and "wholeslide x 2" settings on the OFDA yielded equivalent results for both tops and core samples.  Measurements using 1000 and 2000 snippets gave equivalent results on the Laserscan for tops, but not for core samples.  There were also biases between the two instruments.  The author recommended that more work was required on the Laserscan to establish whether 2000 snippets is adequate to obtain a repeatable curvature result.

Wang, X. (2000). "Predicting the strength variation of wool from its diameter variation." Textile Research Journal 70(3): 191-194.

            Derivation and evaluation of a simple statistical relationship between the coefficient of variation of fibre breaking load and that of minimum fibre diameter.  The relationship indicates that Cv breaking load is about twice CvD.  The relationship has been verified using SIFAN measurements.

Naylor, G. R. S. (2001). Report on an international round trial to establish precision data on the working group draft test method "Measuring the diameter distribution of fibre ends in sliver". IWTO, Sliver group report SG01, Shanghai, China.

            Summarises the results of the round trial to measure diameter distribution both normally and on fibre ends using both OFDA100 and Laserscan.  (The results show better precision than the statistics shown in IWTO-47)

Smuts, S., L. Hunter and M. van Rensburg (2001). "The role of sheep breed and mohair style and character in the OFDA curvature vs staple crimp/wave frequency relationship." Wool Technology and Sheep Breeding 49(1): 53-61.

            Studies how sheep breed and mohair style affect the OFDA100 curvature vs staple crimp or mohair wave frequency relationship.  Good correlations were found for both wool and mohair, and the authors conclude that OFDA curvature can be used as a measure of wool staple crimp or mohair wave frequency without the need to take either sheep breed or mohair style and character into consideration.

Sumner, R. M. W. and M. P. Upsdell (2001). "Factors associated with the prediction of core bulk from fibre diameter and fibre curvature of individual fleeces." Wool Technology and Sheep Breeding 49(1): 29-41.

            The authors consider that it is desirable for wool growers to be able to select sheep for breeding, at minimal cost, according to the bulkiness of their wool.  The paper reports trials evaluating the effects of several farm-related factors on the prediction of core bulk from simultaneous measurements of fibre diameter and fibre curvature using an OFDA100 instrument.  Factors investigated included the effects of breed, sampling site, age of animal and the sire. The trials indicated that core bulk can be effectively predicted under field conditions.  Calculation of a universal relationship will however be dependent on the development of a standard test method for the measurement of fibre curvature.

Swan, P. G. (2001). Understanding fibre curvature. Australian Farm Journal: 67-70.

            Explains how mean curvature and curvature distribution measurement can be used by Merino stud breeders and commercial wool producers.

OFDA 2000

Brims, M. A., A. D. Peterson and S. G. Gherardi (1999). Introducing the OFDA2000 - For rapid measurement of diameter profile on greasy wool staples. IWTO, Raw wool group report RWG04, Florence, Italy.

            Provides a general introduction to the concept of the OFDA2000 instrument and some preliminary results on performance.

Anon. (2000). Fibre formation, fibre properties and processing performance. the Wool Press. 7: 4-5.

            Describes the work of the Wool CRC and refers to research being done on diameter-length profiles using OFDA2000

Mata, G., D. G. Masters and J. Ive (2000). Components of staple strength in young superfine merino sheep from Southeastern New South Wales. 9th Congress of Asian-Australasian Ass. of Animal Production, Sydney, Australia.

            Concludes that the OFDA2000 prediction of position of break is well correlated to the measured position of break (r = 0.73, n = 60, P < 0.01)

McLaughlin, I. (2000). Innovative wool testing - OFDA, Australian Wool Taskforce 2000.

            Description of the OFDA technology and the application of OFDA2000 to in-shed testing.

Oldham, C. M. and A. D. Peterson (2000). The influence of date of shearing on the processing performance to top of mini-commercial consignments of merino fleece wools grown in either southwestern or eastern Australia - 1. Systematic deviations from team predicted values. 10th International Wool Textile Research Conference, Poster session, Aachen, Germany.

            An experiment is described in which sale lot display samples were used to build weighted processing batches (mini-commercial topmaking consignments each ~ 30kg greasy) that mimicked standard commercial 20 tonne containers of Merino fleece wool. Each batch was built to produce tops of 21.5 micron diameter and TEAM predicted hauteur of 68 mm. The wool classer's specification was used to assign each sale lot and consignment to a month of shearing within the 1997/98 wool selling year. On average 3 mini-commercial topmaking consignments were built for each calendar month out of wools either grown in southwestern Western Australia (sold in Fremantle) or eastern Australia (sold in Sydney). Greasy staples were collected from each sale lot used and the fibre diameter profiles were measured on the OFDA 2000. The mini-commercial consignments were sent to CSIRO, Division of Wool Technology, Geelong and processed at random to top through a single combing line using recommended CSIRO settings for 21.5 micron wool. The results showed a dramatic difference in hauteur between wool shorn in spring (71 mm) and autumn (83 mm), but more importantly showed that there is a systematic increase in the deviation from the TEAM predicted hauteur between spring and autumn in wools grown in southwestern Western Australia. In contrast, the actual minus TEAM predicted values of hauteur for the wools sourced out of New South Wales were consistently around 7 mm with little systematic seasonal variation in hauteur. However, for the coefficient of variation of hauteur there was a similar pattern of deviation from the TEAM predicted values for both selling centres; from minimum values (around -1%) in the consignments shorn in spring to maximum values (around -10%) for those shorn in autumn. Similarly, the deviation in romaine from the TEAM predicted values were not large (< 1%) but increased from spring to autumn shorn wools and then decreased again from autumn back to spring in the wools from both selling centres.

Oldham, C. M., P. R. Lamb, G. R. S. Naylor, et al. (2000). Manipulation of the strength or fibre diameter profile of staples and processing performance. 9th Congress of the Asian-Australasian Ass. of Animal Production, Sydney, Australia.

            Reviews the effects of staple strength on hauteur, and summarises work being carried out on using diameter-length profiles to predict processing performance.  65 references.

Oldham, C. M. (2000). The hauteur, CV of hauteur and short fibre content of mini-commercial consignments of tops is strongly dependent on the mean fibre diameter profile of staples of component sale lots. 10th International Wool Textile Research Conference, Poster session RW-P4, Aachen, Germany.

            Describes the relationship between diameter-length profile measurements made on staples from component lots of combing consignments, and the resultant H, CvH, and short fibre properties of the resulting tops.  The author concludes that the effect of fibre diameter profile on these top properties has important commercial consequences.

Peterson, A. D., S. G. Gherardi and M. R. Ellis (2000). "Managing the diameter profile leads to increased staple strength of young Merino sheep in South Western Australia." Asian-Aust. J. Anim. Sci 23.

            The effectiveness of 3 management strategies to increase staple strength was investigated. Length-diameter profile changes were measured using an OFDA2000.  Staple strength was significantly increased by restricting feed intake on green feed after the break of season compared with sheep grazed at low stocking rate.  Restricting feed intake at break of season also resulted in finer wool.

Peterson, A. D. and C. M. Oldham (2000). The influence of date of shearing on the processing performance of mini-commercial consignments of merino fleece wools grown in either southwestern or eastern Australia - 2.  improved prediction from the FD profiles of staples from component sale lots. 10th International Wool Textile Research Conference, Aachen, Germany.

            An experiment is described in which sale lot display samples were used to build processing batches that mimicked standard commercial 20 tonne containers of Merino fleece wool. The wool classer's specification was used to assign each sale lot and consignment to a month of shearing within the 1997198 wool selling year from wool either grown in South-Westem Australia (Fremantle) or New South Wales (Sydney). Greasy staples were collected from each sale lot and the fibre diameter (FD) profiles were measured on the OFDA 2000. The mini-commercial-consignments were sent to CSIRO, Division of Wool Technology, Geelong and processed through to top using recommended CSIRO settings for 21.5 micron wool. Utilising data from the FD profile, a fibre breakage model was developed which predicted the fibre length distribution of the top. The model was able to differentiate differences in hauteur between the consignments that otherwise were under-predicted using the TEAM equation (r2 = 0.38). The model could predict over 73% of the variance in hauteur from 56 consignments. Furthermore, the model was able to predict short fibre content (% fibres < 25µm) of the resultant tops. The new model offers scope for better prediction of wool shorn at different times of the year and offers greater efficiency to topmakers as well as providing a fairer payment to growers who produce longer hauteur wool that otherwise would not be rewarded due to the anomalies of the TEAM equation.

Peterson, A. D. (2000). A new prediction technique for estimating hauteur gfrom the fibre diameter profile. 10th International Wool Textile Research Conference, Poster session RW-P3, Aachen, Germany.

            Describes a prediction process based on fibre diameter profile measurements using OFDA2000.  The model was able to differentiate differences in hauteur between consignments that otherwise were poorly predicted using the TEAM equation.  Over 80% of the variance in the actual hauteur for 56 consignments was explained by the model compared with less than 40% using TEAM.

Schlink, A. C., D. J. Brown and M. Longrée (2000). Role of fibre length variation in staple strength of merino wool. 10th International Wool Textile Research Conference, Poster RW-P1, Aachen, Germany.

            Reports experiments with 16 two-year old merino wethers run together at Armidale, NSW.  Concludes that 93% of the total variation was accounted for by the coefficient of variation of fibre length for fibres longer than the staple length, the square root of the sum of the across and along fibre squared SD values, and the minimum fibre diameter along the fibre.

Baxter, B. P. (2001). "Precision of measurement of diameter, and diameter-length profile, of greasy wool staples on-farm, using the OFDA2000 instrument." Wool Technology and Sheep Breeding 49(1): 42-52.

            The OFDA2000 is an instrument specifically developed to measure wool properties on farm without involved sample preparation. It allows an operator with minimal training to measure a greasy wool staple from an individual animal for mean fibre diameter, diameter distribution, and diameter profile along the staple length, all in 30 seconds or less. Issues related to sample selection and the measurement of greasy wool are examined, and precision data is given for two scenarios of use. This indicates that the single staple measurement regime is of similar precision to traditional midside sampling and testing in a typical fleece testing laboratory.  Prediction of the mean fibre diameter of farm lots prepared using measurements on individual fleeces can be of adequate precision to allow financial benefits to accrue from such a selection process. Estimates are given for confidence limits for 10 key parameters from fibre diameter profile measurements.

Baxter, B. P. (2001). "On-farm classing of animals & fleeces with the OFDA2000." Wool Technology and Sheep Breeding 49(2): 133-155.

            This paper describes the OFDA2000 instrument.  Results of experiments to determine the accuracy and precision of the instrument are compared to documented data for conventional measurement techniques.  These confirm that the measurement system is capable of providing diameter-related data as accurate and precise as that obtainable from a typical fleece-testing laboratory.  Additionally, the instrument provides staple length and length-diameter profile data that appear of adequate accuracy and precision for input into processing prediction models that are currently under development.

Douglas, S. A. S. (2001). 'On-farm testing' revolution. Wool Record: 41.

            Briefly reviews the development of newer technology for both laboratory and on-farm diameter measurement.

Greeff, J. (2001). Is selection of hogget ewe replacements on measurement profitable? 14th AAABG Conference, Queenstown, New Zealand.

            The availability of new measurement technology such as the OFDA2000 and Fleecescan to measure fibre diameter of individual fleeces in the shearing shed, makes it possible to identify the most profitable animals for replacement purposes.  As the phenotypic relationship between fleece weight and fibre diameter is negative, it is important to determine whether selecting replacement animals on fibre diameter alone or on an economic index is profitable.

Lyons, K. (2001). Feeding the young ones. Wool Grower: 12.

            Reviews the use of OFDA2000 diameter-length profiles in managing feed levels, especially with respect to growth between weaning and puberty under New Zealand conditions.

Peterson, A. D. (2001). Report on Fleecescan and OFDA2000 trial - Mingenew Property. Perth, W. Australia, WA Dept. Agric.

            Details the results of a trial between Fleecescan and OFDA2000 on-farm testing technologies, carried out over 3 days at the Mingenew property (which is run under the guidence of the Australian Merino Society).  600 ewes were measured, and 300 were ranked by each instrument.  The results showed that the OFDA2000 was slightly more precise, although the accuracy of ranking of animals was similar for both systems.  The OFDA2000 results on the midside samples gave good agreement with the conventional fleece testing method on midside samples. There was no difference in the abilities of either system to predict the MFD of the whole unskirted fleece.  The Fleecescan suffered from a bias during part of the trial which was undetected during the measurements.  The overall average from the OFDA2000 classed lots was in agreement with the overall average of the AWTA coretests.

Peterson, A. D. and S. G. Gherardi (2001). "The ability of the OFDA2000 to measure fleeces and sale lots on-farm." Wool Technology and Sheep Breeding 49(2).

            The OFDA2000 is an instrument primarily designed to measure the fibre diameter and it's distribution on single greasy staples outside the confines of a laboratory. This paper investigated the precision and accuracy of the OFDA2000 to measure mean fibre diameter and other staple properties that may be used to select individual fleeces, or measure sale lots. The OFDA2000 was close to the precision of commercial mid-side fleece testing when one greasy staple was measured from the mid-side (95% confidence limits = ± 1.2 mm). The OFDA2000 also showed good agreement with the OFDA100 for a range of fleeces (r2 = 0.70; range from 17 to 24 mm). The OFDA2000 offers a low cost method of selecting finer animals and preparing lines of wool based on a number of fibre characteristics. As a result, the OFDA2000 is a serious tool that can be used to improve the income of woolgrowers.

Presented at the 10th International Wool Textile Research Conference, in Aachen, Germany, November 2000:

PRECISION OF MEASUREMENT OF DIAMETER, AND DIAMETER-LENGTH PROFILE, OF GREASY WOOL STAPLES ON-FARM USING THE OFDA2000 INSTRUMENT  

THE INFLUENCE OF DATE OF SHEARING ON THE PROCESSING PERFORMANCE TO TOP OF MINI-COMMERCIAL CONSIGNMENTS OF MERINO FLEECE WOOLS GROWN IN EITHER SOUTHWESTERN OR EASTERN AUSTRALIA – 2. IMPROVED PREDICTION FROM THE FD PROFILES OF STAPLES FROM COMPONENT SALE LOTS

Preliminary precision results:

Precision and Accuracy of the OFDA 2000 , 18 Jan 01

OFDA 2000 in the News

Countryman article - Italians like WA wool tester.pdf , 22 Feb 01

Wool price records set with clips classed with OFDA 2000
New Western Australian State Record
New Queensland State Record

OFDA 4000 Papers (last update: November 2004)

OFDA4000 introduction paper.PDF

ofda4000 Progress.pdf

Experience with the OFDA4000 in two mills.pdf

Improving OFDA4000 vs Almeter Hauteur.pdf

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