<June 30, 2005>

Primer Switch & Recoat Parts

I just couldn’t take it anymore… I switched primers... I had to! I had been using the AFS 1-Part Primer/Sealer, but no matter what I did or what I tried, the primer came out splattered with little bumps and sharp specks on the surface. Over the past few days I have called AFS several times and while they have been extremely pleasant and helpful, none of their suggestions has solved my problems. When I put a few drops of the primer on my hand and spread it around on my finger you could see a lot of grit or un-dissolved solids in the primer, which is what I think was causing the sharp bumps. At the recommendation of AFS I made a little stirring paddle out of some steel rod and chucked it into my drill press as slow speed. I came back an hour later only to find no change in the primer… same un-dissolved solids, same splatters and specs on my parts when I primed. I was even pouring the primer through two medium paint filters before spraying, but it made only a small difference… I got frustrated and gave up. This is a shame, because the cleanup on the AFS was soooooo easy, and since it is water-based it is much safer to use. I really wish I could have made it work for me, but I was wasting time trying to debug the issues.

So today I stopped at an auto paint supply store near my office to talk to the staff. I told them I had done some research and read about PPG’s DP48LF epoxy primer, that I wanted a primer-sealer, and asked them what they thought. They said I was headed in the right direction, and said the DP48LF should do just what I want it to. I showed them a sample of a part sprayed with AFS (with the splatters and bumps) and they said if I followed their directions I would be able to produce superior results. Based on their recommendations I bought a quart of primer, some catalyst, and reducer and mixed it in the proportions they recommended. WOW… I am impressed! Sure this stuff is more difficult to deal with (2 parts, 3 w/ reducer), it is definitely more dangerous, and it is harder to clean-up, but with only a few passes of my spray gun I knew I had made the right decision. After a few coats and an hour or so of drying time I picked up my sample piece to find a silky smooth finish with just a touch of sheen. I was starting to think my problems with the AFS were caused by my equipment or my technique, but when I look at the results I can produce with the PPG DP48LF, I ruled those out immediately.

Update: I let it dry overnight and the next morning I tried to scratch off some of the primer, but no way, this stuff is as tough as nails and it looks fantastic!

The new stuff. From right to left the DP48LF Primer, DT70 Reducer, and DP402LF Catylst. The guy at the paint store said to mix these 2 parts primer : 1 part catalyst : 1/2 part reducer, and he was right, the results are silky smooth.

Ready for blast off! After scuffing up the old primer, I gave a coat of PPG to all the parts. My wife won't stop making fun of me, but I don't want to take any chances with the nasty stuff in the epoxy primer. I got some strange looks from the neighbors too!