I've used Modelflex Paint on a couple of my locos. Crystal Cote should have no effect, since I've used Testors "Glosscoat" and "Dullcoat" on this paint with no problems.
From what I've heard, once Model Flex dries, it is almost impervious to anything. One of it's problems is how to clean it out of an air brush if it dries in it.
