New or used wool should be washed before being used in any project, be it rug hooking, quilting, or appliqué. Washing tightens the weave for a more luxuriant, durable fabric, and contributes to moth-proofing. Wash on a medium setting. Use a small amount of detergent with new wool, and slightly more with recycled wool. Dry on medium heat with a fabric softener sheet to reduce static. Wool can also be dried outside on a line, but shrinkage will be reduced, and the finished piece will be wrinkled and more difficult to work. A piece of new wool fabric that is 18" x 58" before washing will usually shrink to about 16" x 50" after machine washing and drying. The amount of shrinkage will vary, depending upon the weave of the fabric and the temperatures of washing and drying. Because textured wools such as plaid, houndstooth, or herringbone are often of a looser weave, repeat washings or increased heat will help tighten these a bit at the expense of greater shrinkage.