Silk is a natural fibre made from silk worms raised in captivity in temperature-controlled environments that are free from predators.
The momme weight (the weight of 100 yards of silk, 45 inches wide, in pounds) of silk sheet can range from 6-30 mm.
Good quality bed sheets can be machine washed on a gentle cycle in cold water and do not require dry cleaning, as long as a silk-friendly detergent is used. As you continue to wash silk sheets, they will lose some of their luster, but will actually become softer after a few washes. In fact, many people find that they like their silk sheets even more after they have been washed a few times.