Hi, Ipurchased a can of"Red Oxide Primer" from my local hardware store in Brisbane, Australia. I sprayed the bottom hull of my Tamiya King Tiger first . It was out of a spray can. I then tested it on the plastic spare barrel, let it dry and checked for any problems but there was no reaction to the plastic at all. I have not had any problems with applying the top coats with my airbrush. see some sample photos of my KT build. If You want to see more photos go to the "hobby havoc " forum site, click onto Tamiya King Tigers.