If the blouse isn’t dirty, steam it! A steamer kills 99% of all bacteria. Meaning, if you don't have a spot on your silk garment, don't wash it, just steam it and it will feel like new again.

If you need to wash it, you can either choose dry-clean or use the hand wash program on your washing machine. Use a detergent that is free from enzymes, preferably a silk detergent or a special detergent for fine and fragile items (ordinary detergent damages the fat that gives silk its soft feeling).