It is typically okay to wash a silk garment by hand, according to Martha Stewart Living. However, the clothing item should be 100 percent silk. Clothing made of synthetic blends that include silk should be cleaned by a dry cleaning professional.
Other dry clean only garments that are usually acceptable to wash by hand include linen, cotton, and heavy duty polyester materials. These fabrics can also be machine washed on delicate, but a mesh bag is recommended. Garments that should be taken to a professional for dry cleaning include pleated skirts, suits and synthetic blends. These materials tend to lose their shape in water, even when washed by hand.