Silk fabrics are woven under tension, and continue to be under tension during other stages of processing. Therefore, many textiles shrink when exposed to water. Crepe yarns, in particular, shrink noticeably when washed: with crepe de Chine, you may get up to 3 percent shrinkage. Katrina recommends dry-cleaning crepe de Chine to prevent shrinkage.
When fabrics are washed, some aspects of the textile may be changed. The hand and surface appearance can alter substantially. Silks that wash well include silk/rayon velvet and charmeuse (these come out looking brushed). In any case, test-wash a sample to see how the fabric comes out.
To wash silk, Katrina recommends a gentle soap with a neutral pH, such as shampoo. Submerge the fabric in water and see if there is any dye released into the water. Roll the wet fabric in a towel to squeeze out excess water, and press it dry. Now you can compare the washed sample to the original fabric to look for shrinkage and surface texture. If you don’t like the results from washing, plan to dry-clean the fabric and the finished garment.