You can paint it on or spray it on, but why add the weight? If you want UV
protection, there are inhibitors avalible, or lay up your first layer or two
with a colored pigment. I did have a painted on coat (tooling gelcoat for a
mold) crinkle with the first application of cloth. I either waited to
little or too long betweem coats. Walbridges book on boatbuilding is still
a ggood one.