I decided to give DuPont self-etching Vari-prime 615S & 616 Converter a try and see if I liked it. I had use epoxy primer before, and I liked it, but it is heavy and to use it properly you have to Scotch Brite, Alumiprep, Alodine and then spray. It will make your Aluminum plane last 100 years in the bottom of the ocean and add 20 pounds of weight, but it is great stuff if you want your plane to last forever and live on the beach. Since I plan to have the plane professionally painted, I decided to go low tech on spraying using a small gravity feed touch up gun and blow it on at about 40 PSI per the gun instructions. This all eventually worked out fine. I did make some sample test parts just to scratch and sniff. I want to see how well self etching primer sticks to the aluminum. I did half a test piece where I scuffed the surface with Scotch Brite and half without. I cleaned the entire lot with a DuPont degreaser cleaner and it seems like all went well. If I don’t like the results from a toughness standpoint, I’ll go back to an epoxy and just grunt through to prep work and try my best to keep it thin and light. Next priming seesion should take a lot less time, now that I know how to do it.
