How to STOP Rust from Pits

[shwagy357]

I have small pits in my sheet metal on the floor and on one of the doors. I cleaned these areas down to bare metal (with a wire brush) and shot them with epoxy primer. About two years later these spots started to rust. What can I do to fix these areas so they do not rust. Has anyone experierenced a similar problem?

 

[Scoop]

Primer won't stop rust. You need to seal it. Either use a sealer-primer or shoot a top coat of color or clear to seal it up.

 

[jedblake]

Sounds like your job with the wire brush did not remove all the rust.
It looks like you need to sand the area first, use a chemical to nuetralize the rust (like Jasco metal etch, availible at Home Depot) and sand again. You may want to start with the entire door and then move on. I am a big fan of a light skim coat of bondo/poly filler to get back to a smooth surface prior to primer and block sand. I also reccomend a high quality primer two-part (paint & catalyst) availible at your local automotive paint shop.

Body work is a lesson in Patience or is it Frustration....
Jed

 

[Explorer]

You need to kill the rust first. Phosphoric acid converts it to phosphoric oxide which then you can seal/prime/paint. Rust converter from Eastwood, Ospho, and a few others. Or you can buy Klean-Strip prep and etch at local hardware store for about $6 a quart vs $30 quart for the fancy stuff.

 

[00gyrhed]

gem rust killer, they are all some kind of phosphoric acid but the stuff you buy from an auto color supply is usually a higher concerntration that the stuff you get at lowes or the hardware store. The assumption being it will be professionally applied.

I think I paid $8 for the last bottle.

you can clean out all the pit however you do not want to get it on adjoining body work. You can prime right over the traeted surface. I have had parts laying around for a year that were treated with GEM and nothing else. They were heavily rusted and are now still the same dark grey shde lefdt by GEM.

Beauty of it iis it will get into cracks and seams and convert rust you can not get to any other way.

 

[dons68sport]

i have had the same problem in the past now what i do is break a 1/8 drill put it my air drill n clean out the pit if it goes thought in need fix the the pin hole but i have never it blow thought any more have fun

 

[uncle ray]

Primer won't stop rust. You need to seal it. Either use a sealer-primer or shoot a top coat of color or clear to seal it up.

epoxy primer is waterproof. i would suspect not enough coats of primer were used, there was some residual moisture trapped under the primer when shot, or the primer was damaged from rock chips, etc. if nothing was used to treat the metal before primer, there could have been issues with adhesion as well. i suspect the first option, that primer doesn't look very thick. 2-3 good heavy coats would make those pits start to disappear.

 

[00gyrhed]

I had been told....

epoxy primer is waterproof. i would suspect not enough coats of primer were used, there was some residual moisture trapped under the primer when shot, or the primer was damaged from rock chips, etc. if nothing was used to treat the metal before primer, there could have been issues with adhesion as well. i suspect the first option, that primer doesn't look very thick. 2-3 good heavy coats would make those pits start to disappear.

That epoxy was the wonder of the auto body refinishing world and that you could actually spray it directly over stable rust and that it would seal it, and that it also eliminated the need for a sealer. Epoxy first then filler then expoxy.

I didn't let this change how I did things but enough people swear by the 2K primers that I was kind of surprised to see this post.

 

[uncle ray]

That epoxy was the wonder of the auto body refinishing world and that you could actually spray it directly over stable rust and that it would seal it, and that it also eliminated the need for a sealer. Epoxy first then filler then expoxy.

I didn't let this change how I did things but enough people swear by the 2K primers that I was kind of surprised to see this post.

i have sprayed it over stable rust and you heard correct. i shot a project car that then sat outdoors unprotected for 4 years before i did anything with it, upon stripping the old epoxy primer the rust beneath was just as i had left it, absolutely no progression or new rust to be found. that was a typical quickie prep job, removed the old paint and flakey rust with a sander but did not do anything to get into the pits.