In general, any silk fabric is machine washable, especially if they are made with high quality heavy silk. Silk is a natural fabric and with proper care, it can last a long time.
Silk pillowcases can be hand washed because they are small and easy to dry. Using gentle silk friendly detergent such as Le Blanc Silk and Lingerie Wash or Woolite will help remove residue and stain. But if you don't have any silk friendly detergents, you can also use your hair shampoo. The reason you can use your hair shampoo is because silk is a natural fiber with natural protein and amino acids, similar to our hair. Do not twist the fabric and let it drip dry. It will dry quickly because it is a very breathable fabric.
You can also put them in washing machine on delicate cycle and then tumble dry on low. Because silk is so smooth, dirt and residue do not stay on the fabric as well as it does on cotton. However, dry cleaning is the best way to wash your pillowcase because it will leave your silk pillowcase looking new and wrinkle free each time.
We recommend washing your sheets in a cool water setting on the most gentle cycle. We also recommend using silk-friendly detergents. It is also best to wash it separately from other items. For the drying cycle, use the lowest heat setting and for the shortest duration possible. Silk is extremely breathable so if you remove it from the dryer while there is still some dampness, it will dry quickly. This will avoid over drying. Again, for best result, dry cleaning is still the way to go.
Although you can machine wash duvet cover the same way you wash your silk sheets, we do recommend dry cleaning for duvet covers. Mainly because duvet covers are often used as an aesthetic piece.