Hey guys the krylon fusion paint that I used is specifically designed (so it says and it has lasted being parked outside in the oklahoma weather experiment for the last 9-10 months) to bond to plastics including painted plastics. I did not put anything in between. From the forums that I got the info from (read mostly sports car mods) they did not do anything special. I will say that if it has held up in the recent heat wave (we are on record to have the hottest summer ever in oklahoma), it strikes me that it is not going to fail for a long time. I will update this if that happens but right now its still looking good