In this close-up you can see the weave of the silk: gauze-like, so it is translucent. In the area of the loss you can see how the silk has become so brittle that it has broken off. Also, one of the areas that looks as though it is a loss is actually a tear that has folded over on itself. I was able to flip it back when I removed the silking.
Silking is no longer performed as a treatment but was very popular in the late eighteenth and early-to-mid-twentieth-centuries. Now conservators use Japanese tissue, which is made from the fibers of the inner bark of the mulberry tree, is very thin and strong, and doesn't become brittle like silk.