I have sandblasted many small parts including my radiator support. I have applyed a coat of etching primer to the bare metal. I know this is a stupid question but do I need to sand the etching primer before I shoot my sandable primer or just apply over it. Im not a painter but wanted to learn and do the small parts myself.

Both etch primers from PPG and dupont have a time window. On PPG the window is 24hrs, after that the etch must be scuffed and reapplied. I wait around 30-45 mins after shooting etch then come back with my regular primer. No need to sand the etch unless you extend past that 24hr window...Eric

Its been a couple of weeks. Can I scuff it up with some 180 or so and then apply my regular primer?

What I would use is a red scotchbrite pad, avaible at any body shop supply house. Pretty cheap and the best way to scuff up existing paint primer.

Since you have past the time window you MUST scuff up the etch primer then reapply one coat of etch then apply your regular primer. Both PPG, dupont and if I remember right even S-W paint all state in the tech sheets that after 24 hrs you MUST scuff reapply one coat of etch then apply your regular priimer

Eric, that only applys to your typical "wash" etch like PPG's DX1791, their DPX170 and 171 do not need to be recoated nor does Duponts Variprime 615S or 625S. S-W's "wash" style etch E2G973 needs to be recoated after only four hours! And can NOT be sanded, only recoated to start the "window" over again.

Malibu, the thing is you REALLY need the tech sheet on the particular product you are using. What brand and part number is it?

Personally, on things like rad supports and other "hard parts", I never sand them. I use a wash etch, then black epoxy primer then urethane black SS. All without any sanding!

I think most paint producers have all their product data sheets on the internet. I know Sherwin Williams and Dupont have them. I printed them off last week. Martin Senour as well. Just search your paint name and when you find their web site look for their paint data sheets. They answer almost every question you might think of, including the ones you posted here.

The can says Professional Etch Fill. Also on the can is Autobody Master. I bought this at a local paint and body place. The part number is #8467. Any thoughts on what I got?

Martin I stand corrected on the variprime as it just states after 24 hr must be scuffed and the 973 etch from S-W, what about the 980 I believe that etch you had to sand and recoat? I cant remember much about S-W, wish I had their product manuals still.

But I have to somewhat respectively disagree with you on PPG DPX170/1. right out of the P-sheets..after 24hrs lightly scuff DPX primer. MAintain 0.5 mil minimum. Recoat with DPX primer if necessary. It does say If necessary but that DPX goes on pretty thin and after you scuff it or sand it with 180 you can very easily break that 0.5 mil minimum. Eventho it says "if necessary" I would rather be safe then sorry, so thats how I get my somewhat disagree.

I agree with Martin that you should get the tech sheets from your local paint supplier. On those you will find any and everything needed to apply that product. Also agree that I would go etch primer, expoy then SS urethane or even base clear if you wanted to paint it body color

Here is my plan. Scuff what I got, apply MS #5121 Black Epoxy primer, then shoot with Eastwood Underhood black. Will this work?

Yeah Eric, your right, it is likely you would cut through. I have never used the PPG where I would need to sand it. I have used the S-W and Dupont many times and easily scuffed it with a red scuff pad without cutting through.

Malibu, that would be fine. But I'll tell you this, I would put a 2K paint. That Eastwood is a spray can or do you spray it with a gun? I believe either way it is a 1K and soluable. The 2K urethane or enamel will do be damaged with gas and what not getting on it. graemlins/waving.gif

It is the type you spray with a gun. It does not use any type of hardner or activator. What would you suggest to use that would match the black close to factory?