Shrinkage of wool

A. P. Piedot, "Influence of Glass Transition on the Felting Shrinkage of Wool Fabrics," Text. Res.J. (iu press May 1997). 

HERCOSETT 1 25 is a cationic, fiber-reactive, aqueous solution of a polyamide-epichlorohydrin resin. It is used by the textile industry for preventing felting shrinkage of wool, improving abrasion resistance of natural fibers, and as an antistat for synthetic fibers. 

HERCOSETT 125 provides a means of utilizing a highly effective, completely aqueous system for preventing felting shrinkage of wool. The process involves pretreatment of the wool with aqueous chlorine at low pH, followed by neutralization and application of HERCOSETT 125. This process can be used to treat wool sliver continuously, or fabrics and piece goods by a batch process. 

Tokino, S., Wakida, T., Uchiyama, H., Lee, M., 1993. Lanndering shrinkage of wool fabric treated with low temperatnre plasmas nnder atmospheric pressure. J. Soc. Dyers Colour. 109, 334-335. 

Finishing of Wool. Wool (qv) competes for markets where warmth, wrinkle recovery, and abiUty to set in creases are important. Wool problems relate to shrinkage, particularly to its tendency to felt. This is caused by scaly stmcture, which tends toward fiber entanglement when wet and subjected to mechanical action. In order to compensate for this tendency, wool needs to be set and also made shrinkproof if it is to be laundered. 

The surface of a wool hair is covered by keratin sheds, which cause a distinct tendency to shrinkage and formation of felts. This behavior is usually undesirable and thus an antifelt finishing is the most important treatment during the processing of woolen textiles. One of the most important standard procedures, the Hercosett finish, is based on the oxidative treatment of wool by application of compounds that release chlorine. Examples for applied chemicals are NaOCl, CI2 gas, and dichloroisocyanuric acid (DCCA) [14]. 

Ozone is being investigated for shrinkage prevention (182). Wool and blends of wool, cotton, and polyester have been finished to provide improved flame-retardant, durable-press, and shrinkage properties (183,184). Fabrics of these types are often used for uniforms or protective clothing (185). 

Oxidation of the surface of wool fibers is known to reduce felting shrinkage as well as improve other properties of wool fibers (37) Oxidation may be proformed or effected in a number of ways including gas phase plasma treatment (38). 

Industrial Uses. Papain is used in the leather industry to prepare the sides for tanning. Its proteolytic action removes some of the undesirable proteins which adhere to the hide and thus facilitates the subsequent tanning process. In the textile industry, the treatment of wool fibers with papain has been found to reduce the shrinkage from laundering. This appears to be caused by the abihty of the enzyme to destroy the elastic properties of wool protein. Because of its digestive action on protein, papain is used as a spot remover in the laundry and dry cleaning business. 

Plasma treatment of wool followed by polymer application has also been studied [36]. Almost all polymers used currently on pre-chlorinated wool cannot be used on plasma-treated top. Silicone resins applied to plasma-treated wool increase the shrinkage over that for untreated wool. However, the combined plasma/ PMS/Hercosett treatment encompassing the top treatment gives excellent shrink resistance [53]. The polymer after-treatment reduces both relaxation and felting shrinkage almost independently of plasma treatment time. 

The Woolmark Company Test Method TM31, Washing of Wool Products (Relaxation and Felting Shrinkage), New York, 2002. 

Many experiments have been made to modify the shrinkage properties of wool by the application of polymers, but the purpose has generally been to deposit a film on the surface of the fibre so that the D.F.E. will be removed. Alexander (J.S. D.C., 1950, 66, 349) attributes the unshrinkability brought about by the application of polymers to spot welding rather tiian alteration of the surface or masking of the scales the fibres are glued together in the yarn and thus their movement is restricted. 

Photograph from B.S. 195s 1953 Method of determining the shrinkage of knitted fabrics and garments containing wool is reproduce by permission of the British Standards Institution, 2 Park St., London, W.i.)... 

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