rust removal help, phosphoric acid

I have a small area on the drivers side cab corner of my 85 m1008 where the paint is starting to bubble from rust, one small pinhole also. I have read about and used some of the rust converting products in the past with pretty good results but I really want to get this stopped! I have seen the use of phosphoric acid mentioned several times but not alot of detail. How is this used? Do you apply it after wire brushing/sanding to remove residual moisture? Do you let it sit then rise, etc? Thanks much!

Ospho

I have used a product called OSPHO (contains phosphoric acid) to treat raw steel. I acquired it from a marine/boat product catalog whose name escapes me. The company that produces it is the Skybryte company in Cleveland Ohio. It is somewhat expensive, but I did 20 4in I-Beams (20 feet long) with less than a quarter gallon. Some of the steel that I treated was ground down to shiny clean surface and some was left rusty. All of the steel turned a grey/black color with the rust spots being darker than the clean steel. Most of the beams were used inside for a wall stabilization project. They look as slick as the day I installed them ten years ago. The scrap pieces have been stored outside with no protection and they look about the same except that they have acquired a layer of dirt. I think that if they were scrubbed with a stiff bristle brush and hosed off, they would look the same as the inside ones.

In the instructions on the back of the container, it reads "Safely Dissolves Bleeding Rust From Many Painted Surfaces".

Good luck.

More OSPHO info

Quoting from the OSPHO jug.

OSPHO is a rust inhibiting coating -- not a paint. You do not have to remove tight rust. Merely remove loose paint and rust scale, dirt, oil, grease, and other accumulation with a wire brush -- apply a coat of OSPHO as it comes from the container -- let dry overnight, then apply paint.

When applied to rusted surfaces, OSPHO causes iron oxide (rust) to chemically change to iron phosphate, an inert hard substance that turns the metal black. Where rust is exceedingly heavy, two coats of OSPHO may be necessary to thoroughly penetrate and blacken the surface to be painted.

One gallon covers approximately 600 square feet.

Quoting me again, this product has the consistency of water. I brushed it on with a cheap paint brush, but a rag or sponge would work just as well IMO.

Shhhhhh..... You never heard this from me but a cheap and environmentally friendly way to neutralize rust is: Vinegar...

Vinegar - miracle product

Hmmmm, I have used vinegar on galvanized metals to compromise the coating so that it WOULD RUST. But, if what you say is true, vinegar is a LOT cheaper than OSPHO.

Vinegar will neutralize it, not cure it... Leaving metal soaking in vinegar will become corrosive. You need to figure the way to cure it. By either grinding and sealing or cutting it out and weld in a patch...

I've used "Jasso" (I think that's how it's spelled) with great results on bodywork where the panels overlap and rust was forming. Put it in a squirt bottle and drowned the seam and area. Next day wiped down,red oxide primer & paint. Rust never came back. Got it at Lowes.
OSPHO can be found at ACE Hardware near paint and paint strippers for a good price too. If you have bare steel or rust use it and rust won't come back in a few years. Great also when you strip paint or sand blast and won't be able to paint it for a while. Prevents flash rusting. Just follow instructions. Easy to use, just remember it's mild acid so wear protection.

I just looked OSPHO up on line. My favorite resource, Amazon.com has it for $35 a gallon. Considering how much I have paid for other products and how much work can be involved in trying to get rid of rust, I think that's cheap.

I used POR-15 on my truck. Worked well on rust spots that I have on my bed and front fenders. There is a cleaner and a prep spray both from the company. It worked well for my application and no problems.

POR-15 is excellent.
I use white vinegar on all my tools and rusty metals that are portable and I can lay down horizontally. It will mosty just run off on vertical surfaces, and not cling long enough to do the job I desire.

It need sit on the metal for about 15 minutes, then wire brush off. Even a medium nylon bristle brush will do. Then, do it again. It will take it down to bare metal in most instances, EXCEPT where paint has been applied over it to seal in the rust.

The most important thing about vinegar is, you must rinse it off thourally, then paint the next day, or prime, if you can do so. If you don't paint or prime it within 24 hours, it will start to turn orangy again. Plan and schedule your effort well and do it right and you will not have any problems. I've bought the nastiest pipe wrenches and cresent wrenches from GL, put them in a 5 gallon bucket with 2 cups of white vinegar and filled with water and tools, brushed them off 15 minutes later, then another cycle of it, dipped in oil after rinse and dry, and a year later not a sign of rust on these looking like new tools. It's just amazing!

I don't think I would use if for painting a deuce though. Nothing like sandblasting.
If need be, it would probably work fantastic on cleaning up an old rusty bed if it held water, and you dumped a couple of 5 gallon buckets in there and brushed around. Fastest way to clean out the rust you could come by.

What kind of vinegar? Got to be cheaper than Evaporust.

White or apple cider vinegar...

Home Depot has Prep 'n' Etch, it is the same thing as Ospho, only $18 a gallon. It is environmentally harmless, being phosphoric acid which is a fertilizer.

It can be used to completely remove rust. Less work than using a wire wheel, also safer. But slower. It WILL alter the color of paint, turning aged 383 CARC a funky bright green.

For heavier rust, Naval Jelly is better. Again, this is a slow process so let each coat dry. Once dry, cover with wet rags until soft enough to remove. Repeat until you have bare metal, then prime with rust-inhibiting primer and continue with refinishing.

POR 15 Metal Ready.......just used on a snow plow that was completely rusted (and through in a few places). Painted with Rusty metal primer the next day......worked like a charm.

Keith_J said:

Home Depot has Prep 'n' Etch, it is the same thing as Ospho, only $18 a gallon. It is environmentally harmless, being phosphoric acid which is a fertilizer.

It can be used to completely remove rust. Less work than using a wire wheel, also safer. But slower. It WILL alter the color of paint, turning aged 383 CARC a funky bright green.

For heavier rust, Naval Jelly is better. Again, this is a slow process so let each coat dry. Once dry, cover with wet rags until soft enough to remove. Repeat until you have bare metal, then prime with rust-inhibiting primer and continue with refinishing.

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Yep... and a little goes a long way. I wet sandblasted this wheel 2 weeks ago and sprayed some Prep 'n' Etch on it with a $.89 spraybottle. She'll hold until i get some primer and paint on her.

I have never used vinegar but use the ospho stuff. It works better than anything I have found. You can't get it lowes or hd but better ace hardware stores have it in 32 oz. or gallon containers.

gungearz said:

Shhhhhh..... You never heard this from me but a cheap and environmentally friendly way to neutralize rust is: Vinegar...

Click to expand...

You may want to grind as much rust off that you can then saturate the area with muratic acid. It's nasty stuff so do it outside, then flush well with water to neutralize, and let dry. once dry, immediately prime with an epoxy based product.