The Stovebolt Site Forums The Shop Area Paint and Body Shop Surface prep - acid, base, brake fluid?

I knew I had lots of work to do on my roof - there were tons of little blisters in the paint. I stripped all the paint off with a chemical stripper down to the original Chevy red primer. But I can see that whatever caused the blisters has eaten right down to the metal.
Roof 1
Roof 2
Roof 3

Of course I don't know what caused this, but I am guessing some sort of acidic or base liquid. I doubt brake fluid because how would it drip like that? I do know the truck was parked in a carport under a tarp for a long time. Other than a good wash with soapy water, does anyone have suggestions that will prevent whatever substance it is from ruining any new paint I put on? And any tricks to prevent surface rust on the bare metal after I wash it?

Thanks.

Ted,

Are you able to clean it down to clean metal?

- chemical grease remover and/or paint remover
- media-blasting

If you have clean, rust-free metal (even if it is pitted), prime with epoxy. That will seal the surface and stop rust. You can paint later.

not from a 'substance', simple result of tarping directly on the metal, condensation from our acidic atmosphere trapped and 'cooked' over time .... clean it well with a good brand 'wax and grease remover', sand it well, wax and grease remover again, prime and paint .... epoxy primer is best, but I'd get it all to bare metal for that

Bill

Thanks Tim and Bill. I can easily get to metal now and I have wax and grease remover. I am also using epoxy primer.

That was great advice. (It is one thing to ask for advice, another to take it.) By stripping all the primer I am able to distinguish the etching from actual rust. I am going to touch up the rust with the grinder. I have a picture of the truck from about the 70s I think and it has a roof rack on it. I am sure that is what caused the major rust lines. Thanks again Bill and Tim.

The wet sander
Bare metal 1
Bare metal 2