I think I know what you are referring to: I walked into a quilt shop yesterday looking for some yli 100, which they didn't have, but left with a spool of "Wonder Invisible Thread, .004 clear 100% nylon, YLI". I wrapped a snake guide last night with it. It is very fine, clear, a little stretch. Not much fun to wrap, definitely need magnification. I'll try some threadmaster lite on it in a couple days, but like mono, I am a little skeptical about getting epoxy to flow around and under it. I am going to keep looking for some YLI 100 in natural white (I know I could mail order it, but will probably spend a week and 15 dollars of gas trying to find it locally before breaking down and ordering it online.
Michael