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eisej 05-11-2013 07:58 AM

Metal Prep / Conditioner vs. Self Etching Primer
I have a bike tank that I am painting and on it's edges I have some chips down to metal. Otherwise the factory paint is mint. Of course my first thought was that I have to use a self etching primer which bent me because I had to buy more. Then I remembered I had some metal prep/conditioner that I was using to keep some aluminum from corroding after some restoration work I was doing.

My question is, bike tank paint aside, if I have a bare piece of mild steel whether it be a fender or anything else, is it ok, not ok, or "at my own risk" to use the metal conditioner/prep which is basically a very mild type of acid (what type I'm not sure. Maybe phosphate?) and then a primer/sealer or primer filler, instead of using a self etching primer on said bare metal? Of course all other preparations before paint being completed.

Thanks for the knowledge transfer.

tech69 05-11-2013 08:39 AM

metal prep to epoxy is better than a self etching primer in my opinion.

TucsonJay 05-11-2013 02:56 PM

I've been using metal prep (phosphoric acid) since the early seventies with zero issues. It simply changes iron oxide (rust) to iron phosphate... which is a dead gray material that is not in an "ongoing process", like rust is. It also acts as a mild degreaser.

If you pay attention, you can actually watch the rust turn from orange to gray. If a spot is tubborn, just scotchbrite it and wet-and-wipe again with prep.

I like R-Ms 801 prep, which contains alcohol, and does not require rinsing. Just wet it good... let it sit for a moment... and wipe it away. 30-60 minutes later you can paint. ....and you aren't spending unnecessary dollars on primer and labor.

Not everything being sold is necessarily a better idea. Metal prep has been working for around a hundred years.

Chevymon 05-11-2013 07:50 PM

Normally steel and aluminum would require two different types of conditioner.

Old Fool 05-12-2013 07:24 AM

I stopped using metal prep a few years ago when I discovered SPI epoxy. Now I just sand with 80g or blast the rust away, clean with w&g remover and shoot 2 coats of SPI epoxy directly to the metal whether it is alum or steel .
Less products to buy, less products to misuse, and results are awesome.

Pats55 05-12-2013 04:16 PM

30 years using Metal Prep never a problem either

BarryK 05-13-2013 10:04 AM


Originally Posted by tech69 (Post 1674785)
metal prep to epoxy is better than a self etching primer in my opinion.

Both PPG and Dupont have an excellent metal prep process, if you follow their instructions to a tee, if not good luck.

deadbodyman 05-15-2013 05:36 AM

X-2 ,metal prep to epoxy,,,,also back when I did use etch primer (duponts variprime) filler didnt stick to it very well...

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