Phosphoric Acid Question

WD9ER · Jan 16, 2012

I have been using "The Must for Rust" to stabilize the surface of parts on my WD-9 as I have been stripping it. I have noticed that if it puddles and sits on the surface for an extended time that it leaves a white residue behind. Do I need to worry about leaving this on the surface before primer? Or do I need to wipe it off or sand it off?

CNKS · Jan 16, 2012

Move it around with a brush and it won't puddle. The white residue is normal. I scuff the residue with a scotch brite pad, then use wax and grease remover, which you should use with or without the acid, and most of it comes off. Some paint over it but I don't like painting over residue of any kind.

George Rausch · Jan 17, 2012

Yes I'd remove all residue. I used some on my Farmall gas tank, to stabilize some rust film, and I painted over it. It still bubbles the paint up, after I've sanded and sanded and re-painted.

CNKS · Jan 17, 2012

Regardless of what it says on the bottle, Must for Rust and Picklex 20 are more for prevention of rust on bare metal than they are rust converters. If you had a lot of rust on that tank, it was only partially converted. As a converter I use it only on pits I can't remove or on inaccesible places where I can't manually remove the rust.

WD9ER · Jan 17, 2012

Thanks for the feedback everyone. This is my first time using the product so I would rather be safe than sorry before I paint. Regardless I would be using a wax & grease remover to prep the surface. @CNKS If Must for Rust is only for prevention of rust on bare metal, what do you recommend for a rust converter? There are hard to reach places that I should probably do something about prior to paint.

showcrop · Jan 17, 2012

(quoted from post at 06:51:46 01/17/12) Thanks for the feedback everyone. This is my first time using the product so I would rather be safe than sorry before I paint. Regardless I would be using a wax & grease remover to prep the surface. @CNKS If Must for Rust is only for prevention of rust on bare metal, what do you recommend for a rust converter? There are hard to reach places that I should probably do something about prior to paint.

What CNKS is telling you is the same that he and I and others have said various times before on this forum. Which is; rust converter is necessary for the little tiny bits of rust left in pits cracks crevices etc. but is not a replacement for removing rust down to clean metal.

Dodgeit · Jan 17, 2012

"What CNKS is telling you is the same that he and I and others have said various times before on this forum. Which is; rust converter is necessary for the little tiny bits of rust left in pits cracks crevices etc. but is not a replacement for removing rust down to clean metal."

I agree, I use Jasco prep and prime on every piece. It also leaves a white residue, which I scuff with a Scotchbrite pad, blow off with air gun then wipe down with laquer thinner when I'm ready to paint.. I've never had paint lift, even after the Jasco'd piece set for three years in the building waiting on me to get back to working on the tractor.

CNKS · Jan 17, 2012

I usually don't use rust converters--Takes a lot more time manually, but then I am sure I got all of it. In the places I simply cannot get to, I will give it a squirt of Must For Rust or Picklex 20. If it lifts the paint in those areas they are not visible anyway. These are usually cast pieces. But, I usually don't use rust preventers on cast because I am afraid I won't be able to get it all out of the pores then it WILL lift the paint. Others have done that successfully though. Otherwise I only use preventers on bare sheet metal, and usually not even there because I live in a dry climate. I have left bare metal for months with no problems.

Phosphoric Acid Question

WD9ER

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CNKS

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George Rausch

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CNKS

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WD9ER

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showcrop

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Dodgeit

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CNKS

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