I know what you are talking about, I had the same problem recently with feathers on a giant war eagle.

 I mounted up the parts solidly and then went back with Tamiya 2 part epoxy putty, which dries overnight and is very workable until then. I worked the texture , and worked it and worked it using toothpicks carved to shape as well as straightpins and my knife blade until I had feather texture that pretty well matched the original.

the Painting Girls manual by Andrea Press says that hair in 80MM girls can be made or restored by using tiny balls of epoxy putty rolled out into long snakelike pieces, then laid up on the hair a strand at a time. In 100MM scale you have a bit more working room and can lay up strands to match the 'lay" of the hair, then use something like a fine toothbrush to recreate the texture of the hair.

HTH

David