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Tue Jan 18, 2011 6:26 am

hi if i had a bare metal surface and then painted it with a etch coat how long can i keap it like that? (i am going to start the paint process, high build yada yada)

will it keap the moisture out well?

Tue Jan 18, 2011 6:38 am

I wouldnt be too worried as long as it isnt outside.

Tue Jan 18, 2011 8:34 am

It depends on your climate. Etch primer contains an acid that chemically etches to the metal and seals out moisture. You could get away with it for quite some time if your car is in the tight setting---even if it was outside.

Tue Jan 18, 2011 9:10 am

I think epoxy primer works better as a moisture barrier. I wouldnt personally use etch primer. I like to be able to use a metal conditioner if I need to, and metal conditioners react with etch primer....so i just dont use them.

Also etch primer has no build or fill properties to it, but the epoxy will actually fill some of your scatches in....so I dont see ANY reason to ever use etch. Epoxy also has some chemical rust inhibitors in it, so to me its just a more versitle product.

If you think that there is ever a chance it will sit outside before its painted, then when you spray your epoxy dont topcoat it, or even sand it, that will help it seal out the elements.

Wed Jan 19, 2011 8:46 am

buguy wrote: I think epoxy primer works better as a moisture barrier. I wouldnt personally use etch primer. I like to be able to use a metal conditioner if I need to, and metal conditioners react with etch primer....so i just dont use them.

Also etch primer has no build or fill properties to it, but the epoxy will actually fill some of your scatches in....so I dont see ANY reason to ever use etch. Epoxy also has some chemical rust inhibitors in it, so to me its just a more versitle product.

If you think that there is ever a chance it will sit outside before its painted, then when you spray your epoxy dont topcoat it, or even sand it, that will help it seal out the elements. epoxy is not waterproof...it is water resistant...which means that it will rust if left outside any length of time.And im not sure what you mean ...rust inhibitors...it doesnt have acid in it.

Wed Jan 19, 2011 9:13 am

I didnt say it was waterproof? Epoxy has chemicals in it that help inhibit rust, I dont remember what they were....but your welcome to reserch it if you really want to know.

If you know of something that is waterproof, let us know what it is so he can get it on his project, but I guess he didnt even say it was going to be left outside....guess we got off track a little bit.

His original question was how long can etch be on there? And I would say.... along time, just have to scuff it before topcoating it.

And will it keep moisture out well? I would say, yes it would be about as good as anything else. Just personally i think epoxy will keep moisture out better, and then has building properties that etch doesnt... so i think its a smarter product.

Wed Jan 19, 2011 9:19 am

ppg DX 579...THEN 520 conversion coat...then 2 coats epoxy...WATERPROOF!!!!!

Wed Jan 19, 2011 10:03 am

how good is primer surfacer?

Wed Jan 19, 2011 11:41 am

Those metal preps dont make it anymore waterproof then regular epoxy would be. They just clean/treat the metal. Still a good idea, but not waterproof.

In fact as far as I know there is nothing you can put on an autobody that is waterproof. The closest i would know of is clear coat.

But the closest you are going to get is treating the metal, then epoxy....oh and dont put it outside...that will help!

Wed Jan 19, 2011 11:44 am

luckyvw13 wrote: how good is primer surfacer?

That will provide about zero rust protection. In fact it will hold moisture in, and probly be worse than having nothing. Besides, epoxy isnt any more expensive.....plus.....if you get the right kind, it can be reduced and be used as a sealer before paint. Good and good.

You MIGHT be ok if it will never see the outside with regular primer...but i dont see the point.

Epoxy is better in every way for rust protection, and if you are planning to take it to metal anywhere...you have to get it or something like it because primer/surfacer isnt a DTM (direct to metal) primer. Is there a reason you dont want to use epoxy? I dont see why you are fighting this so much?

Wed Jan 19, 2011 4:22 pm

buguy wrote: Those metal preps dont make it anymore waterproof then regular epoxy would be. They just clean/treat the metal. Still a good idea, but not waterproof.

In fact as far as I know there is nothing you can put on an autobody that is waterproof. The closest i would know of is clear coat.

But the closest you are going to get is treating the metal, then epoxy....oh and dont put it outside...that will help! yea it does...they did a test at PPG training center..took a bare piece of metal tape it off then treated one side with 579 then 520 took the tape off then 2 coats DP epoxy..3 years ago took my Masters certification at PPG and the piece was still there and thats when i took my blue certification yearsago..the side they treated did not rust at all.I learned that years ago.So you cant tell me it dont work to be waterproof.

Wed Jan 19, 2011 4:32 pm

So are you saying the side that only had the epoxy on it did rust??

You already said that epoxy isnt waterproof, and a metal cleaner surely isnt waterproof, so that would mean that you are saying that the metal conditioner is what is waterproof in that scenario?

I dont doubt that the piece didnt rust, but I dont belive that it is waterproof. That is pretty much how I treat every paint job I do, and I have never had a problem with rust coming back. Appriciate the info....we are all learning here!

Wed Jan 19, 2011 6:10 pm

buguy wrote: So are you saying the side that only had the epoxy on it did rust??

You already said that epoxy isnt waterproof, and a metal cleaner surely isnt waterproof, so that would mean that you are saying that the metal conditioner is what is waterproof in that scenario?

I dont doubt that the piece didnt rust, but I dont belive that it is waterproof. That is pretty much how I treat every paint job I do, and I have never had a problem with rust coming back. Appriciate the info....we are all learning here! the side that was treated with PPG 579 and 520 did not rust... the side that was untreated did rust and if any of you use PPG and have a training facility close to you u can take the classes..its not jus open to people in the trade...all can go.Plus you get free stuff. yea if its bare metal i treat before epoxy. safe insurance

Wed Jan 19, 2011 6:54 pm

Cool...good info!

Wed Jan 19, 2011 7:55 pm

You have zero time
Immediately after you grind and etch- you need primer
Otherwise you are locking in the water molecule
Should have never ground it down to begin with
This is what they made sealers for