Do you think the yellowing on white thread is because the epoxy yellows no matter what and it's easier to see the contrast over the colour white, or can it be avoided using CP first even though you might be using NCP white thread?
I've noticed that Bullards D2 is a clearer epoxy than the TM I'm using at the moment. I haven't tried using the ProCote epoxy yet but maybe soon.
I like using the TM Light Formula because I can get a longer working life out of it but it is more yellow out of the bottle to begin with.