If you have a wool sweater that's just a little too big, shrinking it on purpose might solve your problem. Shrinking wool fibers is possible with the use of heat, water and, for heavy-duty jobs, the washer and dryer.
Understanding Wool Fabric
Though true wool is made from sheep hair, the term may also refer to fabric made from goat, vicuna, alpaca or camel hair. Wool shrinks fairly easily when agitated in any way. Although heat is commonly believed to be the main catalyst in shrinking wool, it is not. In actuality, it is the agitation from washing that rubs wool fibers together, causing the hairs to continually lock into one another, tightening and shrinking through the process. Heat, though, can still gently shrink wool, especially when the fabric is blended with other materials, in particular rabbit angora.
Shrinking a Wool Sweater
To lightly shrink a wool sweater, start the process with a clothing iron. Put the iron on its wool setting and steam the sweater by hovering over the garment, allowing the steam to penetrate the fibers without actually touching the fabric. Continue until the desired size is achieved.
For heavy-duty shrinking, place your wool sweater in the washing machine on its normal, warm water setting. Although the washing machine method can significantly shrink a wool sweater due to the increased friction, it may often lead to uneven results. Check the shrinkage of your sweater throughout the wash cycle. Then, place the wool sweater in the dryer on a low or medium heat setting. However, be warned: Not all wool sweaters are candidates for shrinking in the washer and dryer. Soft wools, such as those made with woolen yarn, or any angora blend, may be too delicate and prone to excessive shrinkage when placed in any wash cycle, and shrinking with this method should be avoided.