This weekend I am going to put epoxy primer/sealer on the sandblasted body shell of my '51 Chevy. The whole body had heavy surface rust. Even after the blasting it has light surface rust here and there. My plan is to D.A. the bejesus out of it with 80 or 100-grit, wipe it down with Ospho, then primer. I have used Ospho and I've shot epoxy primer, but I have never shot epoxy primer over Ospho before. What do I need to know in order to make this work?
your on track, do a search on ospho I think you should find several...post up some before and after pictures if you have some.
Hey, Who's epoxy are you going to use? Not all are for use directly over the phosporic acid in a metal conditioner/rust remover! Check with your paint vender and the product lable, so this works out , well for ya! Swankey Devils C.C. "Spending A Nation Into Generational Debt Is Not An Act Of Compassion!"
Should't need the 80 or hundred with the OSPHO. spray on the acid, work the areas with medium or heavy scuff pad. wipe it down to remove the loosend rust, then spray it with the acid again and let it dry. The coating thats left is supposed to be inert and will protect the bare metal for a year or more inside. If you want to paint use self etching primer over the Ospho, after a light scuff. then you can do the epoxy over the etching primer.
the epoxy primer i used on my olds was PPG shop line 2 part epoxy black primer, good stuff and tough as nails BUT it is maid to go on bare metal or scuffed factory paint, i used some filler primer on a few spots to smooth out needed areas and well.. the epoxy primer didnt like it and the spots i used the filler primer the epoxy made it crack ( wrinkle) also used rust converter on the hood roof and trunk lid since they were bair metal and needed some attention, i had no issues at all with that and the primer
I've used PPG DP series epoxy over OSPHO treated panels with good results; the PPG spec sheets for the DP epoxy say there is better adhesion when applied over a conversion coating, which is what I believe OSPHO is.
I read over at another paint and body forum that using epoxy over rust converters was not a good idea. I will be getting my sedan media blasted in a couple of months and am also worried about the metal flashing before I can get it home. I already have the PPG DP epoxy and like the idea of treating the bare metal so I don't have to worry about the possible flash rust but don't want to start over if the epoxy doesn't like the Ospho. Not
I've read stuff since I first posted, including a lot of HAMB posts that mentioned Ospho and my plan has changed to this: this weekend I'm going to coat the whole thing with Ospho and that's it. I did not realize until last night that it would not only stop the minor surface rust that I have but also keep the metal from rusting any more. In a few months when it's no longer 100 degrees out I'm going to scuff it and shoot it with DP90 or similar. I trust the guy that I buy paint and supplies from and he says he's got epoxy primer that works really well over an acid converter. So there you have it. Thank you to everyone for the feedback.
dupont makes a metal conditioner to go under there primers, but I use 250s epoxy primer under ospho all the time. But you may want to check because like was said before not all primers are created equal.
any time i have bare metal that is going to lay around a while i shoot a light coat of ppg 1791 its great stuff simple to use. they call it wash primer
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