Silk is an acidic fabric and sensitive to alkaline materials, such as baking soda, borax, and washing soda.
Any harsh lye-based soap with a pH above 10 will destroy silk. Hand wash silk in a sink by gently swirling the clothes in cool water; never twist or wring silk.
A mild liquid castile soap, such as Dr. Bronner’s baby soap, is best for cleaning silk because it won’t strip the natural oils.
Shampoo–with its ability to remove body oils and neutral pH–can be a good choice for washing silk that has been stained; just a little dab is needed. Gentlly press water from the fabric after washing and hang the silk to dry.
Spot-clean with vinegar or lemon juice, but test for color fastness first.
