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I seem to be seeing alot of cases where people using acid etch primer over bare metal get bubbles in their paint after a while. I plan on trying the SPI epoxy primer everyone is so hot on for the remainder of my project, But on some areas of the car i've used acid etch primer. I'm new to these things so I'm not real keen on the Do's and Do not's. Basically all i'm looking for is a good paint job that lasts, just like all of you are i'm sure. Is acid etch a no no? :)
 

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This is a very sensitive subject as many people here have used in the past and present "Acid etch" Primers.

Here is the problem, first the paint companies will not just pull this product because it is so cheap to make unlike epoxy or 2k primers.( Its a big money maker) The next problem is acid etch works very well under lacquers and enamels (20 years out of date) but the product never locks down so if you sprayed a fender with acid etch and let it set two years, you could walk up with Urethane reducer and wipe off.
So what does 2K primers, base, and clears have in them urethane reducers!
So what happens is the urethane reducers melt the the acid etch and you don't know it. So depending how much sun the car gets
the "pinhead" type bubbles can show up in a week or 10 years.
The reason for the bubbles is when melted the solvent along with the air in the vinyl acetate that the acid etch is made of start rusting the top surface and soon a little bubble will show up, if you pop the bubble it will look like rusted water and if you blow on it, it will go to bare metal.

NOW !!!!!!!!!!!!!!!!! Does this mean every acid etch job is going to blow up? NO !!!!!!!!!!! As is the case with using lacquer primer!
But the odds are against you!

Also to throw this in the bucket of worms, another reason to not use it is it has very poor long term corrosion protection! No better
than the top grade 2K primers out there.

If it was my car and only two choices of 2K primer or acid etch, I will use the 2K primer, for safer long term results!
Now let me make myself clear having said that I would never use 2K primer over bare metal on a Restoration job!
This is as short and sweet as I can be on the subject.

Someone on this site brought a beautiful car over for me to look at this weekend. It was painted around 10 years ago and not driven much and a great paint job that still looks new except for the pinhead bubbles here and there. I tested a piece and sure as can be its has 2K primer over acid etch.
So now it gets stripped a second time.
Why even chance it?
 

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Discussion Starter #3
Excellent that was exactly the advice I was looking for. Yeah, I saw the post about the acid etch on your buddy's car, I'd still be crying if it were mine. I knew there was something screwy about it to begin with but I used it (thankfully sparingly) anyway. Kinda like when you tell someone not to touch something It's hot, they do it anyway.

Thank you for clearing this up. Knowing this now I know exactly what I am going to use. :thumbup:
 

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maybe i am misunderstanding what you are saying so let me try and clear it up please.
you are saying not to use etching primer at all? or just when you have to?
What if i have to strip an entire car down to bare metal, mainly to remove several coats of different paint and to see what i am starting with.I was told if i take anything down to bare metal that i should always coat it with etching primer first then other primers, such as filler primers, then a sealer type primer.
Is this wrong to do it that way, or just not the best way to do it?
If that is the case can you please tell me what you recomend over bare metal first?
thanks..
and i am in no way trying to steal the original posters question, just meerly trying to elaborate/clear things up
 

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yes that is my car :(

i am extremly grateful to barry for taking a unbiased look at problem. but it makes me extremely ill to think of costs i will have now - be very sure of that.

dont make a mistake, you have the advantage of good info from nice folks here. i wish i had this resource 10 years ago.
 

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project66 said:
maybe i am misunderstanding what you are saying so let me try and clear it up please.
you are saying not to use etching primer at all? or just when you have to?
What if i have to strip an entire car down to bare metal, mainly to remove several coats of different paint and to see what i am starting with.I was told if i take anything down to bare metal that i should always coat it with etching primer first then other primers, such as filler primers, then a sealer type primer.
Is this wrong to do it that way, or just not the best way to do it?
If that is the case can you please tell me what you recomend over bare metal first?
thanks..
and i am in no way trying to steal the original posters question, just meerly trying to elaborate/clear things up
++++++++++++++++++++++++++++++++++++++++++
Your correct!, I'm saying I know of no need to ever use it!
Use an epoxy over the bare metal and if the epoxy says you must use an acid etch, its no good to Begin with!
 
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