color preserver compatibility?
You shouldn't have to worry about color preserver compatibility when using Flex Coat. Any color preserver (within normal shelf-life bracket!) will work fine as long as you let the coats dry inbetween applications.
Gudebrod makes a good one (their new one thins with water instead of lacquer thinner, a nice improvement).
But here's a thought: I've built more then 20 fly rods, all for personal use. I just built a 13' 6" Sage double hander and tried a new approach: NO COLOR PRESERVER ON THE THREAD WRAPS.
Why? Because I was sick and tired of "crazing" (cracks and discoloration appearing in the Flex Coat finish, especially on the thread wrappings around the feet of the stripper guides).
Here's a story: I built a SAGE 9150-4 a fgew years ago: I put a tremendous amount of time into the wraps and colors and the finish coats-- the rod was an absolute beauty! On its maiden voyage I hook and land a 25 lb steelhead (true story). Not much of a fight, but a big fish nevertheless. I beach it, turn it loose, slap myself on the back, then a week or so later I notice that the Flex Coat finish on BOTH stripper guides on the 9150-4 had cracked and discolored. I felt like I'd been kicked in the stomach-- re-doing Flex Coat is not an easy task!!
So I figured out the reason--- Using color preserver can trap air in the thread wraps which in turn keeps the Flex Coat from soaking into the threads properly and producing a strong bond. So long story short, with no color preserver used on my latest SAGE rod, I went up to the North country this October and hooked lots of burly steelhead. LO and behold, no cracking of the Flex Coat on the stripper guides! The thread (purple and gold!) looks as new as the day the rod was built. I can't quite see what improvement thread color preserver would have done to make it look better. Just something to keep in mind when you build your new rod. Good Luck...