University of California

The determination of yield and shrinkage of wool by scouring small samples


J. F. Wilson

Author Affiliations

J. F. Wilson was Associate Professor of Animal Husbandry and Associate Animal Husbandman in the Experiment Station.

Publication Information

Hilgardia 11(4):149-172. DOI:10.3733/hilg.v11n04p149. January 1938.

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The accurate determination of wool shrinkage is essential to the proper conduct of biological investigations of quantitative wool production. It is equally important to the woolgrower. The clean weight of a fleece is far more significant than the grease weight in the selection of breeding animals, especially rams whose offspring are to be retained for breeding. Besides being important biologically, shrinkage is intimately associated with all commercial aspects of wool production. The price of the commodity is quoted on a clean basis, and each 1 per cent difference in the shrinkage affects the value per pound of either the individual fleece or the whole clip 1/100 of the quoted price. Thus, if fine combing wool sells at 90 cents a pound on a clean basis, an increase of 1 per cent in the shrinkage decreases the value of the grease wool 9/10 of a cent a pound. A grower with a band of 1,500 ewes shearing, on an average, 10 pounds each might be affected to the extent of $135 by a 1 per cent variation in shrinkage, provided the clip is sold strictly on its merits.

The factors influencing shrinkage have been pointed out in another paper,(1)3 which showed that California wools may shrink from 30 per cent to as high as 80 per cent.

Proper technique in shrinkage determinations has been studied over a long period at the California Agricultural Experiment Station and elsewhere. Hardy(2) once recommended scouring the entire fleece for the most reliable results.

Literature Cited

[1] Wilson J. F. Wool production and improvement of the clip in California. California Agr. Ext. Cir. 1937. 106:1-61.

[2] Hardy J. I. Methods of wool scouring suggested for sheep husbandry investigators. U. S. Dept. Agr. Bur. Anim. Indus. Booklet. 1927. p.13.

[3] Wilson J. F. A method of determining the clean weights of individual fleeces of wool. California Agr. Exp. Sta. Bul. 1928. 447:1-21. (Out of print.)

[4] American Society of Testing Materials. Standards. Part II. Standard method of estimating hard scoured wool in wool in the grease 1936. pp.232-36.

[5] Hartshorne Wm. D. Unit system charts showing the relations between humidity and regains on wool and cotton. Natl. Assn. Wool Mfgrs. Bul. (Reprint) 1915. p.20.

[6] Hardy J. I. Wool yield and fleece density can be measured by a simplified method. U. S. Dept. Agr. Yearbook. 1934. 1934:1-783.

[7] Burns Robert H., Johnson Alexander. Predicting the yield of raw wool from its density under pressure. Amer. Soc. Anim. Prod. Proc. 1936. 1936:1-341.

[8] Miller W. C., Bryant D. M. An apparatus for scouring small samples of wool and a modified apparatus for determining dry weights. Jour. Textile Inst. 1932. 23(11):T267-T273. DOI: 10.1080/19447023208661558 [CrossRef]

[9] Fisher R. A. Statistical methods for research workers. 1928. 2nd ed. London: Oliver and Boyd. 269p. DOI: 10.2307/2981200 [CrossRef]

[10] Wilson J. F. Combing tests with individual wool fleeces. Textile Research. 1934. 4(12):570-582. DOI: 10.1177/004051753400401205 [CrossRef]

[11] Bosman Victor. Biological studies on South African Merino wool production. IV. Jour. Textile Inst. 1937. 28(9):321-353.

Wilson J. 1938. The determination of yield and shrinkage of wool by scouring small samples. Hilgardia 11(4):149-172. DOI:10.3733/hilg.v11n04p149

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