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Etch primer necessary?
#263181 Sat Jul 16 2011 04:58 PM
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So I just got a pump back from the sandblaster... he claims that the sandblasting has done the etching for me and I don't need to use self etching primer, which is what I've always done. It would be great to go straight to filler primer, but I had always thought that self etching primer formed a bond to the surface of the metal on the chemical/molecular level.

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Re: Etch primer necessary?
chrisbowers #263190 Sat Jul 16 2011 05:33 PM
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I've always gone straight to acrylic primer surfacer after blasting with never a problem on my pumps. The shop that I retired from, we used a lot of shiny aluminum guards on our machinery. We'd sandblast first then go to regular primer and finish coat with never a problem either.

Re: Etch primer necessary?
Savinsam #263227 Sat Jul 16 2011 08:29 PM
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If the pump is going outside I use epoxy primer, if inside I use high build primer and go from there.


Thanks, Phil
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Re: Etch primer necessary?
Savinsam #263228 Sat Jul 16 2011 08:31 PM
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The recommendations from the paint companies have changed over the years. I'm sure millions of cars, gas pumps and other metal items were coated in the past with primer-surfacer over bare metal with acceptable results. Paint materials have been vastly improved over the years as well as expectations for the performance of the paint holding up. In order for the paint company to give a lifetime guarantee for a pro applied paint job, most require etching primer to be used over bare metal.

My experience has been that etching primer out-performs primer-sealer or primer-surfacer for adhesion on bare metal in the long run. And that 2-part catalyst primers out-perform non-catalyst primers.


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Re: Etch primer necessary?
Oldgas #263261 Sun Jul 17 2011 06:53 AM
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Originally Posted By: Oldgas


My experience has been that etching primer out-performs primer-sealer or primer-surfacer for adhesion on bare metal in the long run. And that 2-part catalyst primers out-perform non-catalyst primers.



Yup!


FREEDOM oil items wanted.




Re: Etch primer necessary?
Ryan Underthun #263274 Sun Jul 17 2011 08:04 AM
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There are some direct to metal 2 part primers on the market now such as 2K 3 in 1 primer by transtar.Has any one used these?

Last edited by billyd; Sun Jul 17 2011 08:04 AM.
Re: Etch primer necessary?
billyd #263464 Mon Jul 18 2011 11:03 AM
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Pump is going to be inside a garage so perhaps I'll try straight to surfacer this time. The metal is uniformly etched from the sandblasting so I would think it would adhere pretty well.

Re: Etch primer necessary?
chrisbowers #263479 Mon Jul 18 2011 12:27 PM
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Be careful, there are some surfacers out there that are not recommended to go over bare metal at all. If the p-sheet says you can apply it over bare metal you should be ok.


FREEDOM oil items wanted.




Re: Etch primer necessary?
Ryan Underthun #263959 Wed Jul 20 2011 08:53 PM
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I would agree that etch primer has superior adhesion properties and does offer corrosion resistance.Problem with etch primer is that it generally doesn't have any filling characteristics and while blocking surfacer applied over etch primer,if not careful, you can block right through the etch primer. On media or sandblasted metal,I would agree with Phil on using an epoxy primer. If parts are aluminum or galvanized,then etch primer is highly recommended for adhesion. With an epoxy,you still need a surfacer. Billyd is right about the 2k direct to metal primer surfacers. They do offer corrosion resistance. PPG doesn't offer a direct to metal primer in the Omni line(less expensive). NCP270,271 would be rather expensive for gas pumps. There are several generics out there including the transtar which would work fine on a gas pump. Jim is right about 2k surfacers, much better than 1k lacquer based primers though they will work. Key to lacquer primer is to use a high quality thinner(not cheap as most people do) and after blocking,to let it sit for a week or two(allow for shrinkage).Should then use a 2K sealer over lacquer primer. One thing everyone needs to remember is that with most 2K primers,they have an isocyanate based hardener which is not good to breath,even with a respirator.PPG's epoxy primers do not utilize isocyanates in their hardeners.NCP270,271 don't have iso's either but they sure do stink.Got to remember,a gas pump may sit outside,but it isn't going to be going down the road at 70 mph. Pat



Looking for early Pure Oil Company items(Energee,Detonox,Puritan)as well as any Woco Pep items.

Looking for graphic quart cans for my collection.

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