How should I treat the rough surface of a freshly sand blasted frame. I don't want rust coming back. Thanks. Ray
The best thing is to spray it with thinned POR 15, then top coat it with with chassis black. I have done this it works great!
After I sandblasted my '66 frame, I went over the surface with a DA sander and 80 grit paper to smooth the surface some more. I wet it down with metal conditioner (Picklex 20), wiped dry, then applied epoxy primer. Primer surfacer was applied on some areas with minor surface pitting, and sanded smooth. For a top coat, I used a semi-gloss black epoxy from Tenaco. in Mn. If you search the chassis resto forum, there are posts by myself, Limemist GSX, and Jim Weisse detailing the Tenaco epoxy. It's nice stuff!
A sandblasted surface is the best there is for adhesion as long as it's dust free. I would thoroughly blow the frame off with good clean dry compressed air and spray it with epoxy primer. You never want to use an acid etch product on a sandblasted surface.
I'd agree that an etch is not necessary to improve adhesion on a sandblasted surface. I do like to use the Picklex metal conditioner to prevent rust from forming on a freshly blasted part. Otherwise, bare metal will rust overnight here in Pa. Is it a bad idea to use metal conditioner/etch on a sandblasted surface? or just not necessary?
Thanks guys for all the advice. :TU: I already have epoxy primer so I think I'll go that route. I have some etching acid with phosphoric acid in it to etch the metal. I thought it would get the rust pits out of the frame after I got 98% of the rust off but it didn't do squat and I don't want any rust sealed so I borrowed a blaster. Very messy but I think it'll be worth it. StratoBlue72 Can I ask what is the reason why I should not use etching acid on the metal before priming? And what would you recommend? Walt Is Pickex a etching acid or a weaker kind of metal prep acid? Ray
Ray, there is more information on Picklex 20 here: http://www.icpi.net/ http://www.autobodystore.com/r-o-n.htm Here's a quote: "A combination metal surface cleaner, surface rust remover, 100% rust converter (including mill scale), conditions metal and provides a conductive metallurgical protective coating for long term rust protection, all in one application."
Thanks for the reply & links Walt. I''ll have to see if the Picklex it is available in Canada. What I blasted two nights ago is already surface rusted. Seems to be a mild etcheing acid from what I read on the links. Looks like what I need. Thanks. :TU: Ray
From what I was told, the acid soaks into the pores of the sandblasted surface and gets trapped. A metal conditioner such as Martin Senour Triple Etch leaves a phosphate coating on the bare metal, but is not recommended or necessary on a sand blasted surface. If used properly on a sanded bare metal surface the conditioner is great, but only needed if your primer is non chromated or doesn't have zinc phosphate. If you already have some flash rust started then you would probably want to touch up with a sand blaster to clean it off and get it covered with epoxy right away. The problem with using a metal conditioner like Triple Etch on something like a frame is that it runs into places that you cannot wipe off. Like on the sandblasted areas that are boxed in. The best epoxy primer we have found is the R-M Polyuroxy. It's a 3 component polyurethane/epoxy hybrid that is chromated. It's kind of expensive to use and it's very fussy on how it's mixed. R-M also has a few other 2 component epoxies, DE15 (zinc phosphate), DE49(chromated), and EP589 (chromated). We have always had the best luck with the green colored epoxy primers, but nearly any of them should have excellent adhesion over a sandblasted surface.
How about powdercoating it? Thats what I did to mine.The costs were about the same. $450 to do frame,rearend,both sway bars,front and rear control arms,crossmember,spindles w/backing plates.All done in chassis black,or cast iron
That would be a really good option unless a person needs to fill rust pits with a filler or primer surfacer. I wish we had somebody within a reasonable distance that did powdercoating.
Mine was not perfect by any meens. I used a product called All Metal to fill the "pits" in. Its a 2 part system,after it hardens,you just sand it.It stands up to the heat of the powdercoating. My powder guy is just outside the Cleve,OH area if anyone is interested
I wasn't sure how much heat was involved with powdercoating. But as long as aluminum filler like All Metal or Metal to Metal can handle it that would be a nice way to go.
