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Flash rust problem

R

redrr

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I have a issue with flash rust on some body panels I sandblasted. I was going to treat with rust mort, but then read that rust mort acts like etching primer ,with they say not to use with epoxy. Can someone tell me if I can epoxy prime over rust mort. Thanks
 
I wouldn't. You want to sand freshly blasted metal with 80 grit and get it in epoxy as soon as possible.
 
Unfortunately I can't get to some areas well. It's a very orange light rust. I know Rustmort will eliminate it. I'm just concerned about the epoxy primer over the treated areas. I'm using PPG OMNI MP170.
 
I should know this, but I'm not sure. Why run a test with Rust Mort & see what happens. Otherwise, I think your only choice will be to use some rattle can primer. Fresh metal will rust.

Maybe some professional body shop guys will chime in?
 
This is an interesting question. I'm subscribing! I am faced with the same problem.
 
I have used Picklex 20 with very good success. Apply it after sandblasting and work it in with a scotch pad, let it dry and as long as you store the panel indoors it will last indefinitely. When it is time to paint I normally lightly sand although they say you don't need to, epoxy prime and paint. I have had panels go for 1-2 years done this way with absolutely no signs of rust forming. Good stuff
 
Sand as much as you can and shoot it with Southern Polyurethane's Epoxy Primer. It self etches and the flash rust won't be a problem say the pros on their forum.
 
JimKueneman said:
Sand as much as you can and shoot it with Southern Polyurethane's Epoxy Primer. It self etches and the flash rust won't be a problem say the pros on their forum.
Click to expand...
I did it on a rusty roof of a car. Stripped the roof, used rustmort. Then I used all metal on the worst pits and spi epoxy followed with 2k primer. That was in 2007 and no problems yet.
 
Great advice! Went to auto paint store this morning. According to them it's ok to epoxy prime over rust killer as long as it is neutralized with water. Also spraying primer over light surface rust shouldn't be a problem. (Not convinced). So here goes nothing.
 
redrr said:
Great advice! Went to auto paint store this morning. According to them it's ok to epoxy prime over rust killer as long as it is neutralized with water. Also spraying primer over light surface rust shouldn't be a problem. (Not convinced). So here goes nothing.
Click to expand...

Be very careful with the definition of neutralized. If the stuff has dried the ONLY way to get it off is the spay MORE of it on to reactvate it and then hit it with the water to wash it off.
 
I'm restoring my dad's truck where the hood and roof are solid rust... no paint, I used SEM's chemical treatment. I sanded as much off as I could get then treated, seamed to work well but only time will tell. I can look when I get home but it's a 2 step process that you mix with water and spray on with a spritzer bottle then rinse with water, first I believe removes rust and the second chemically treats the remaining rust. It turned all of the surface rust black so??? The instructions say to topcoat with epoxy.

In the future a dehumidifier works wonders to prevent it from happening again.
 
as a rule, I try not to sandblast more than I can prime; that being said, I've had blasted stuff sit days and weeks and never rust, just don't touch it....... deep surface rust on the outer skins is always a major problem, I try to avoid it like the plague
 
i have used eastwoods afterblast product before with good success..
i have thrown dp 90 on it with no problems
but priming right away is the way to go..
 
Agree, Barry only recommend Ospho if you really must use something. He would rather you used nothing but water and his 700 and 710 wax and grease remover. Not that I am trying to push SPI here but look at this on what can happen if you don't correctly remove the chemical treatment......

 
Last edited:
Please do not prime over or cover over any rust, sooner or later that one will bite you.
180 on the DA should remove any surface flash, any areas you cant get to with the DA or by hand , re blast , then clean with a grease and wax remover then epoxy prime with PPG DP 50 or even just a good polyester primer.
 
Mission accomplished ! After rust mort, pressure washing, spot sandblasting, DA sanding forever, gallon of wax and grease remover I was ready to spray 2 coats of epoxy. that's after having the car blasted and sanding it to bare metal. Lesson learned... never prep a car in 95 percent humidity. If I had waited 24 hours the humidity dropped to 59 percent! cost me hours of work. but its done for now thanks again for the input.
20170906_190533.jpg
20170906_190505.jpg
 
Looks good. Amazing how much work is still left after media blasting.
 
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