Brand new silk sheets are generally wrinkle-free, smell nice and feature deep, rich colors. Every washing-and-drying cycle moves your silk sheets one step closer to the trash bin, so using silk sheets right out of the package helps prolong their durability and allows the consumer to enjoy the silk sheets’ new look and feel after purchase.
If your skin is reasonably robust and your nose sufficiently tolerant, or if you just can’t be bothered, then don’t wash new silk sheets. It is not exactly dangerous, and you could argue that you save water, electricity and laundry detergent. By not washing the silk sheets unless it is dirty, you do a service to the environment.
Washing or not washing new 100% mulberry silk sheets is a matter of preference. If you like your silk sheets soft and smelling nicely, wash. If you want to save work, time and money, then don’t.