Keeping fly heads from yellowing

Just about all epoxies we use in fly-fishing will eventually yellow...

Q: I've been using epoxy in the bodies and heads of my flies. But I've noticed the epoxy yellows over time. How can I prevent this?

A: First, I don't think it matters to the fish. For example, I have used Deceivers that were tied identically, but some heads were yellowed while others tied more recently were not. I could not discern that one was more effective than the other.

Just about all epoxies we use in fly-fishing will eventually yellow. Bob Popovics, whom I consider the most innovative fly tier I have ever known, has a solution. He uses a special epoxy called Tuffleye. It requires exposure to a special lamp, which is not inexpensive, immediately after tying. But Bob tells me that when using Tuffleye and this lamp, the epoxy remains clear.