Heres a trick that the pros use when doping up full size aircraft,in the event that the weather is humid or damp and you really must dope then the chances are the surface will bloom and give unsightly marks,this is caused by the moisture getting trapped in the dope as it dries very quickly,a way round this is to nip down your chemist (you call them drug stores I believe in US of A ?) and buy a small bottle of oil of wintergreen,simply add a couple of drops to your dope tin and mix in,this will do the job and stop any blooming,great tip eh !!