Are there any cold galvanizing compounds that can be painted over? I have some areas on my car where the paint is lifting but where water normally gets trapped (under weatherstripping), so I'd like to do more than just paint over it the usual way. Is it OK to simply use phosphoric acid metal etch or etching primer over cold galvanizing paint, or will this cause it to lift?
I've used Centari acrylic over ZRC cold galvanizing paint with no problems on my frame rails. You can't use alkyd paints over zinc rich coatings. On sheetmetal, treatment with phosphoric acid followed by a primer and topcoat should be sufficient.
These are usually labeled zinc rich primer, meaning to me they are meant to be painted over. I did a job for the dept. of transportation several years ago that specified galvinized pipe, with all welds sprayed with zinc rich primer, followed by 3 coats of paint. I had them painted by an outside source so I can't tell you particulars, but I can tell you it can be done.
JTMcC.
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The problem is that all spray zinc primers I've found in the stores and a half-used can that was obtained from an industrial supply house had warnings against being painted over. I just haven't had luck finding anything that says it can be painted over, and since with zinc-plated metal supposedly needs special primer, I though that the same would be true of anything coated with cold galvanizing paint since it's 95% zinc powder.
The info is at
Try Clearco Products, I have bought hundreds of cans from them, they are good to do business with and they have zinc rich spray thats made to be painted over. I know this stuff is routinely painted over in high corrosion enviroments, the DOT stuff we built was underwater part of the time.
JTMcC.
I use this
regards tim
I suggest Rust Bullet. See
I have no idea,
Indeed. You can't use any kind of normal pain for that, because regular paints aren't waterproof. All will allow a few water molecules through, and that's enough to cause rust.
There is however a rather expensive plastic 'paint' that is absolutely waterproof and which will stop rust dead in its tracks. It has no problems with being painted over. After two salt- laden Canadian winters my winter 'beater' still shows no sign of rusting where I've applied that stuff.
An unsolicited testimonial from a satisfied customer.
I don't know about "no problems being painted over." If you let POR-15 harden, you have to *really* scuff it up to get paint to adhere to ir. It is, however, uneqivocally Good Stuff. Only gotchas about applying it: 1) it WILL NOT adhere to grease, so while surface rust is just fine and dandy, you usually end up using some powerful degreasers if you want the stuff to stick (I usually use it on frames etc. and underneath the engine requires lots of prep work) 2) if you get any on you, wipe it off right away with lacquer thinner because if it dries on you, it's there until your top layer of skin is ready to be scrubbed off.
Oh, and if you're using it in a non-underside-of-car application, you will want to topcoat it because the color fades in sunlight.
nate
It has an optimum paint-over 'window' about 3 hours after it is applied. After that you need to rough it up. The problem is that it doesn't dry, it hardens the same way silicone adhesive does, from exposure to atmospheric moisture. Local humidity affects drying time.
Do you know anything that does?
My one lament is that they don't make the stuff in clear anymore. At least that didn't show so bad on your skin.
It gets sort of dull and weatherbeaten looking. But in that condition it takes a topcoat really well!
Bonus: you can use it with fibreglass instead of the usual epoxy resin to make patches. Unlike such patches that use epoxy, POR15 ones won't rust out underneath their bonding surface.
Yup, that's what I do, spray a mist coat of primer over it while it's still tacky.
Not really :) I guess what I meant was that the POR-15 will peel off in big sheets if there's any grease as opposed to regular paint which will just remain soft locally.
It's a badge of honor :) Unfortunately when you have a semi-professional job that means you get to wear long sleeved shirts a lot.
Haven't tried that...
Oh yeah, I forgot to mention that. That's great for stiffening up rust weakened but still intact floorpans, and under carpet, who's going to know?
nate
Your nice clean shirt or whatever else is clean Alan in beautiful Golden Bay, Western Oz, South 32.25.42, East 115.45.44 GMT+8 VK6 YAB ICQ 6581610 to reply, change oz to au in address
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