It is usually best to follow the cleaning instructions for garments; however, washing machine manufacturers sometimes include instructions for using a delicates cycle to wash items such as silk shirts. Most experts advise handwashing silk shirts and other silk garments rather than using a washer. However, Texere Silk points out that it is possible to machine wash many silk garments if it is done with care.
Make sure the silk shirt in question is pre-shrunk and colorfast before laundering it in a washing machine. In addition, a silk shirt should be machine-washed only if the washing machine has a cycle specifically designed for delicate items. The normal gentle cycle on a washer may be too rough for a silk shirt, which can be damaged by agitation. Only a very mild detergent, such as Woolite, should be used. Avoid any detergent that contains enzymes or brighteners.
Wash silk shirts at the lowest possible temperature, as heat may cause shrinkage. Adding white vinegar to the rinse water may help keep white silk from yellowing in the wash. Choose the shortest possible spin cycle to minimize the amount of agitation the silk must endure. If using a top-loading washer, it is a good idea to place the silk shirt in a mesh bag before washing.