Painters, what do you personally do to neutralize Ospho on rusted areas where rust was removed with abrasives(sandpaper etc) before primer/sealer After Ospho treatment, Do you wash with baking soda solution? Wash with detergent and water flush maybe some denatured alcohol(or other solvent) before primer sealer? Or just wipe down with reducer or D. alcohol? Or?
Primed right over it with what? rustoleum or alkyd enamel paint? I dont thing you are supposed to do that with a epoxy primer or any auto primer . I think the Ospho label kind of says to do that... I know it says to scrub off the grey/white residue and wipe down with solvent first before painting over .
The SPI epoxy website states to neutralize, if dry reset with ospho and let set 1-2 minutes, then with a clean rag and water, wash off like washing the car and dry. Next DA with 80 grit, clean with wax and greas remover, let dry an hour then shoot epoxy. On miscellaneous yard stuff I just apply ospho and paint over it with rustoleum no issues.
The only people who can answer this question with any sort of meaningful response is the manufacturer of your primer.
Posted about "Neutralizing" Ospho techniques ...................... not about primers or manufacturers . Thank you . .
Neutralizing is meaningless if the primer manufacture doesn't allow it's use or the use of acids under their primer. And you did talk about primers when you said you didn't think automotive primers could be sprayed right over it.
I have used both Ospho and Rust Mort in the past. The Ospho must be wet to neutralize it. If dry, just spray it down with water (I use a spray bottle from the dollar tree) and wash it like you wash your car with clean rags but no soap. Dry it when done and then I hit it with 80 grit DA then thinner or reducer (whatever I have left lying around to clean it) and spray epoxy primer. Never had an issue.
https://skybryte.com/pdf/OSPHO-Technical-Bulletin.pdf This never mentions neutralizing before paint, simply let dry, 24 hours
It doesn't require neutralizing. But, if there is any white grainy deposit on the surface it needs to be sanded clean. Or you can wash it off, I just don't like water on bare metal that I'm working on, Some epoxy makers don't recommend applying over any acid product, SPI being one. Others like my choice, Kirker, is fine with it and even sell their own acid based metal prep.. I've used a lot and never any issues doing it that way.
So it seems if you have bare bright steel and want to stop rust forming a light coat of ospho, let it dry fully and when you are ready paint over it. Cleaning with water on a large item like a chassis would be very difficult to avoid trapped water and flash rust. NEW METALS For new Ferrous metals, remove dirt, grease, and oil, apply OSPHO ni a thin coat, let dry for a minimum of 24 hours, then apply paint. Longer dry times may occur depending on temperature, humidity, and over-application of product. Adry, powdery, greyish-white surface usualy develops when cured. Brush of any loose powder and wipe down with Mineral Spirits before painting. OSPHO penetrates deep inside of the metal's pores ot convert and protect before Iron Oxide si present.
I’ve done it this way with “rust converters”on flimsy panels we didnt want to blast like roofs and hoods. And some floors that were heavy pitted. Strip the panel to bare metal. Clean as much rust as possible from pits. (3m black stripping wheel) Apply the rust converter per instructions. DA the panel with 80-180. Per primer instructions. Prime as normal. In theory the converter handles the small areas you cant reach.
What if one was to use a spray bottle to get OSPHO into a cab where the inside/outside and drip rail are spot welded together ( 3 layers ) .... or inside the opening of the upright posts ( hollow ) ( left and right ) support the windshield and roof ?? What I am meaning is places you cannot sand or brush away deposits ?? I have never dealt with this before on all the vehicles I have painted Perhaps it would help the OP as well Ricky
It's not ideal, but when I need to deal with this I use a blow gun to remove excess Ospho before it dries. That way there isn't (or shouldn't be) any of the white grainy stuff to remove. Then I apply a LOT of epoxy primer, spray, pour, brush or whatever is needed to cover everything and soak into lap joints. And the first coat of epoxy is overthinned to help with the lap joint part.
I'm literally on the beach and use Ospho on everything. Never neutralized it and never had any problem with it in many years of use. I spray it and then wipe it with a cloth. This will help it dry evenly, eliminating any chunky buildup. I scuff it with a red SB pad, wipe it with prep and go.
Water neutralizes it. Sounds counter intuitive I know, but the phosphoric acid has already etched it by then and the water doesn't rust it. You get that bluish/orangey type tinge in the metal, that's your coating. Do about a section the size of a door at a time. Not in the sun Stay away from acid etch primers or epoxies that adhere by acid etching ... Ppg shopline epoxy says not to put over metal conditioned steel from memory, check the data sheets. Use an epoxy urethane, spi epoxy is perfect
I did a write-up about this several years back (2008) and it went into some pretty detailed discussions. Here is one of the cars, 53 Olds, I covered in ospho and used it the way I described in the post. Painted in '09 with no issues of ospho popping up or causing issues. https://www.jalopyjournal.com/forum/threads/phosphoric-acid-a-pictoral.263091/
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