Epoxy Primer vs. Etching Primer

[Machspeed 219]

My car will be media blasted in the near future and I wish to bring it home and shoot a coat of protective primer on it. The primer I had originally thought to use was Epoxy Primer, however, I'm hearing and reading all kinds of differing opinions on both primers. I have messed with both of these primers (epoxy and etching) on a small scale...very small.... and without a doubt, Epoxy was always the way to go for what I did, as the stuff just sticks. Now, I do not plan on painting my car and in fact spoke to a local guy and perspective source for painting my car and even he said etching primer. Thoughts and comments on this?

[3Must 10]

I would say etching primer over bare metal.

[69mi 10]

i would say epoxy primer(it seals out moisture), but if your paint guy says to use etching primer i would do what he says.

 

later if there a bonding issues and you dont follow the advice of the painter he will blame you. the etching primer and buildup primers(if sanded) will absorb moisture just sitting in the garage.

[buening 63]

Thats been a common debate on autobody forums. My opinion, pick a system and follow the instructions. If you go with SPI, they specifically state they don't recommend using etching primers in their system. I've seen people only use self etching primer, only epoxy, and I've even seen people use epoxy primer over self etching primer. I think if you pick the brand (SPI/DuPont/PPG) and follow their instructions, you should be golden.

[Klutch 17]

FWIW, I have also seen this topic debated much online. After reading many of these debates, I opted for the SPI epoxy primer. (Just ordered it yesterday.)

 

Based on my research, self-etching primer is a good product. But the epoxy primers are a newer technology. Although certainly not always the case, in this case, it seems the newer technology is also a better technology.

 

What's also nice about the SPI epoxy is you just mix it 1:1 with activator, let it rest a few minutes and shoot it. Easy peasy.

Edited August 8, 2012 by Klutch

[Machspeed 219]

Yeah, I hear you on the painter. My experience with Epoxy just tells me it is the better, though. And, it is in fact SPI that I have used. SPI is relatively inexpensive and is a top notch product.

[Lemon Owner 11]

As said previously etch primers do not seal so rust can form underneath if left for over a month. So it sounds like epoxy is the go for your situation.

[Ash 145]

Another here for SPI. After reading for months now I've read over and over the negative effects of not following a manufacturers instructions, mixing brands and not use epoxy primer over clean neutral metal that is scratched with 80grit on a DA. The guys don't like etching primer as well as any rust treatments. Everything gets sealed with SPI epoxy. Inside and out. Even engine blocks.

It took me about 6 weeks to have some SPI epoxy shipped to Australia, it's now in my shed and waiting for me to get my body work done to give it a go. I also have SPI 2K high build and their water borne wax and grease remover. Once they're done I'll be using the SPI black base with SPI universal clear. All the same brand following their instructions. Barry and everyone else there is incredibly helpful and help is only a phone call away, 7 days a week.

 

Here's some examples, not from their own website.

 

http://www.mustangandfords.com/techarticles/body/mdmp_1208_sheetmetal_repair_thick_skinned/independent_front_suspension.html

[CandyAppleRed 10]

Etch primer is awesome stuff. But it's not intended to be a protective coating. It is intended to neutralize microscopic corrosion that begins forming as soon as metal is bared, and to bond to the metals surface in preparation for a seal coat, typically epoxy. If you are only applying one coat and expecting it to protect the metal for a period of time then you will want to go with an epoxy. If you want the best possible outcome for your final paint job in my opinion use PPG etch followed by PPG epoxy following their instructions. Your metal will be sealed and protected.

[TheMenace 10]

I went back and forth on this debate and I was about to get etching primer and went to a local paint store. I read online that SPI can be brushed on so when I went to the shop I asked for an epoxy primer to use that I can brush on. The guy told me he never heard of a primer that can be brushed. I told him to go to SPIs site and read the file that have on the primer. After reading all the stuff in there he told me to forget buying anything he can offer and go with their product bc it is a lot better than whatever he can offer and a lot cheaper. I was sold on SPI at that point.

[CandyAppleRed 10]

I went back and forth on this debate and I was about to get etching primer and went to a local paint store. I read online that SPI can be brushed on so when I went to the shop I asked for an epoxy primer to use that I can brush on. The guy told me he never heard of a primer that can be brushed. I told him to go to SPIs site and read the file that have on the primer. After reading all the stuff in there he told me to forget buying anything he can offer and go with their product bc it is a lot better than whatever he can offer and a lot cheaper. I was sold on SPI at that point.

 

I have nothing against SPI but that's just a bit odd. Was that an auto paint store or a house paint store?

[BuckeyeDemon 211]

I went back and forth on this debate and I was about to get etching primer and went to a local paint store. I read online that SPI can be brushed on so when I went to the shop I asked for an epoxy primer to use that I can brush on. The guy told me he never heard of a primer that can be brushed. I told him to go to SPIs site and read the file that have on the primer. After reading all the stuff in there he told me to forget buying anything he can offer and go with their product bc it is a lot better than whatever he can offer and a lot cheaper. I was sold on SPI at that point.

 

why couldn't you brush on other brands of epoxy?

 

why would you want to brush on epoxy?

 

anyone here recommending SPI have any significant experience with other products?

[69RavenConv 286]

why couldn't you brush on other brands of epoxy?

 

why would you want to brush on epoxy?

 

anyone here recommending SPI have any significant experience with other products?

 

I'm no expert by any means but I've used SPI products. They make a nice product at a good price and provide good customer support which has endeared them to small shops and DIY-ers like me. I have no complaints.

 

Having said that, there's nothing magical about their product. I'm sure any name brand epoxy primer will perform just as well. It's a matter of price, familiarity, and convenience (i.e, mail order), that decides whose product you use.

 

FWIW, I tried brushing their primer on some door hinges and was not pleased. I wanted to avoid the hassle of firing up the compressor and cleaning the gun afterward, so I tried a brush. I ended up re-shooting them with the gun a couple days later with the gun.

[fastwayfirebird400 14]

I've used PPG DP Epoxies and paints since the 90's never had any issues. I did my last Full restoration (68 Firebird 400 convertible) with all PPG products.

I have since started using SPI epoxy on my car 69 Mach and a 68 Coupe a guy hired me to do metal work on. It's about 1/2 the price of PPG lays on nice and seems very durable. The guys are always available to speak with as far as tech support I'm looking forward to using more of their products on my own car as well as the 68 coupe I'm working on.

 

PPG has a huge customer base, they make a good product but I think SPI has come along and are able to really compete and make as good or (some very successful restoration fab shops have said) better product for about 1/2 the price.

 

Here is a pic of my 68 Firebird 400 when it was nearly finished

[Lemon Owner 11]

As Buckeye said why, oh god why would you use a brush after you have the car media blasted?

[Nightowl 10]

I stopped down this morning after work (midnight run) to the body shop to show him my trunk lid. We have a big sand blaster at work, so I put it in there, and just hit the areas that I wanted him to look at. After seeing what I had, he recommended getting a new deck, because you could see the built up rust along the edge, and he thought that it might cost more to fix it, then if I bought a new trunk lid, and they would paint it. I know it will never be flawless, and the lid I have, would work with no problems, but I needed to fill in some holes, but he said they could do it, but was it worth it, as he said the rust will come back, and they don't skin trunk lids. Anyway, getting back to this subject, he said to go with the 3M etching primer. I saw what it cost him, and it was 13.00 a can. Since I am going to try to bead blast the inside of the trunk area, with walnut shells, I will use that primer as the first coat. I also plan on doing the door jams the same way, since the colors are different from original.

[CandyAppleRed 10]

As others have said. Use a complete paint system. Don't have layers of primers/paint from different manufacturers. It's asking for trouble. If at all possible use an etch primer, epoxy primer and so on from the same manufacturer.