An egg veil is any sort of fine, white material used to imitate leftover skein on an egg pattern.





There are a variety of different ways to do it, but this is one product that is commonly used.

http://www.caddisflyshop.com/egg-veil.html

Since I was never able to find this particular product at my local fly shops, I have tried some different things. One that I have had similar success with is White Glo Bug yarn. I pull it apart until it is fine enough to lightly cover the egg pattern.