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How reliable are rust converters?

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PostPosted: Sat Jul 18, 2009 7:08 pm
I have the Mar-Hyde rust converter. This isnt a showroom restoration so I was planning to wire wheel the entire underside of the car, spray the rust converter, then epoxy, then bedliner as undercoating. Just curious if anyone has ever used MarHyde or POR15 and painted over it. How did it turn out?



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PostPosted: Sat Jul 18, 2009 8:28 pm
Screw the rust converter. Just hit it with some epoxy and then the bed coating. I use this great stuff I found at home depot, called "rust eliminator"... It's in a yellow and black box and the label says Dewalt angle grinder on it :)

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PostPosted: Sat Jul 18, 2009 10:12 pm
You have to use a rust remover or converter under POR15. If you do like it says and Paint Over Rust, you'll be asking for trouble. :x
It is best to media blast and epoxy prime, then apply your bedliner. This provides a good CLEAN surface for your materials to adhere to. Rust will continue to grow unless it has been converted and is topcoated once 100% dry. Otherwise you will trap moisture and have bubbling rust forming under your paint.

2nd best would be to wire wheel the S--- out of it, along with a good Rust Remover (contains phosphoric acid), use at the same time. After you remove as much rust as possible, rough it up with 80-grit paper. Then you can epoxy prime or POR15 it. The Metal Ready stuff they sell with POR15 is a glorified phosphoric acid rust remover which converts rust to iron phosphate (inert black material).

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PostPosted: Sun Jul 19, 2009 4:34 pm
Your taking a chance with any rust converter used under paint. I had to redo the roof on my car because of the film a rust converter left that caused poor adhesion. Didn't show up until buffing the car and then a small blister would raise up. When I began to repair the blister I found the problem was everywhere I used the rust converter.
Blast the rust out, epoxy prime and then proceed. I would only use rust converter in areas that you cannot blast and paint.
1968 Coronet R/T - a work in progress.


ACTS 16:31



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PostPosted: Sun Jul 19, 2009 5:12 pm
Thats what I was planning on doing. I have a blaster gun from HF but it doesnt work that well. The best results are when the gun is no more then 1" away from the rust. Some angles and corners make this impossible.

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PostPosted: Mon Jul 20, 2009 6:32 am
http://autobody101.com/forums/viewtopic.php?t=13070

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PostPosted: Mon Jul 20, 2009 2:48 pm
The point is, you can't just paint over a metal converter or rust remover...you have to rough up the surface first. I don't rinse with water 90% of the time. If I'm doing a large area and rise it off, I dry the metal immediately so the flash rust doesn't form. What little yellowing I get is easily cleaned up with a little P120 on a DA.

The problem is, people try to paint directly over the converter without providing some "tooth" for the primer to stick to, sand scratches. The other issue is people only do a half-**** job of cleaning the metal before applying the converter so it makes the rust crust up and the surface flakes off, taking the primer and everything else with it. If you remove the crusty rust and blast down into the pitted metal, the surface will be clean and ready for primer.

As far as blasting into hard to reach areas, you have to get creative. If you have a rotten area, cut out the metal and reach the blast nozzle in through the hole and blast the area inside. Get creative with your angles and pressure setting. If I can't get within 1-2" of the surface, I crank the pressure up around 120PSI and let it fly while holding the nozzle far enough away to not damage the surrounding metal. Normal blasting pressure is between 40-80PSI for me. A pressure pot blaster will give you a little more distance and a wider blasting area. I use the pressure pot on large blasting area and keep the siphon feed blaster for working very small areas.

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PostPosted: Mon Jul 20, 2009 7:18 pm
if you are not rinsing then you are removing that zinc coating that it leaves behind with the da and the 120 which is perfectly fine. just gotta get that film off.



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PostPosted: Mon Jul 20, 2009 10:49 pm
Im not sure we are on the same page. I am talking about rust converters like Mar-Hyde or POR 15. The kind that ( turns rust into a black primer paintable surface.

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PostPosted: Mon Jul 20, 2009 10:57 pm
i dont think you can paint on top of por. please dont quote me since i wont go near the stuff but dont you have to put a special adhesion promoter on por to get anything to stick to it?
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