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To etch prime or not.....

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Discussion starter · #1 ·
The car is going to the media blaster in a couple of weeks. Then it is heading to a jobbers shop for priming before I get the body work done. The guy doing the priming is going to use R-M brand primer (do not know the number), but when I asked if he was going to etch prime first....he asked why I wanted that. I have undertood from posts on this site from Martin and sevt that etching was alomost mandatory.

My guy says he checked with the "rep" and he told him that etching was not necessary... :confused: :confused:

Do I demand he etch prime...or go with his experience....seems to know what he is talking about and he is the guy of choice for Strip-it, Inc...here in our area...

Any thoughts....

Mike
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#4 ·
Agreed, etch primer application is cheap insurance, what i would insist/demand is to see the tech sheet for the product applied. For instance DP-20 Diamond Prime is a very common 2k Urethane r-m primer. Its a nice product and does a great job, only problem i have with it and the reason i rarely use it is...must be topcoated within 12 hrs.
 
Discussion starter · #5 ·
Can I have him etch prime with the R-M and then have my other body work done...Quarters, wheelhouses and trunk...and then go back and re-etch and then epoxy prime to finish...???
 
#6 ·
You should really review the tech sheets to find out what will work with the products applied, i was just giving you an example of rm products i use. RM has other products that don't have that requirement, but its still best to review the product before its too late. About the etch, atleast the RM i use DE-17 and De-18(activator), "do not apply polyester body fillers ontop of diamond etch." That make sense? The bondo's hardener could react with the etch(proably the activator). They recommend spraying Dp-20 or 21 right over it.
 
#7 ·
Take a poll of your local body shops, I think you will find that they do not use etching primer except in very rare occasions, and in certion places. My shop has not used a full galleon in the last 20 years. And i`ve never had any problems with paint adhesion. And I have won hundreds of paint awards at the ISCA shows (world of wheels ).HTH.

Troy-Curt
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#8 ·
Troy, I agree and disagree with you. First you are right most production shops probably dont use etch.

But have to disagree with you on not using etch at all. First the car is entirly bare steel, unlike most production shops were you only have small spots of bare metal.

Etch primer is bar none the BEST protection you have against rust. It works its way into the metal fighting rust on a molecular scale. Epoxy does nothing like that it just lays on top. Etch will convert minor rust specs into a harmless form. No other product that i know of can do that.

Topcoating bare steel with a urethane primer surfacer will DO NOTHING TO FIGHT rust. ALL PRIMER SURFACER DOES IS LEVEL OUT MINOR SURFACE IRREGULARITIES(sp?).

I have tech sheets right here at home for PPG, dupont, Valspar and S-W at work, each one of their primers RECOMMENDS the use of an etch primer first for max performance.

To achieve the lifetime PPG warrenty on paint you MUST follow specific guidelines, and what do you see DX1791(etch primer) listed as the recommended product to be used on bare steel. Not epoxy not urethane primer or these new DTM primers, ITS ETCH PRIMER.
The same goes with dupont paint Variprime(etch) for the lifetime warrenty. Epoxy finally shows up at the 5 year warrenty!!!!!!!

Why bust your ass doing all that work in getting new panels welded in or dents straighted and to only then use a product thats NOT the best product avaible??? Doesnt make sense to me

My advice is find out about the R-M products throu tech sheets and find out for yourself if what he is doing whats stated on those sheets.
Ask him NICELY to take you throu each step and what products he will be using. Then go about your research.

Ask them what excatly do they plan on suing to protect the bare metal.

You cant build a house without a foundation, you can but it'l collapse, so why paint on something without the proper foundation???...Eric
 
#9 ·
Most production/collision shops dont use etch prime.Its not cheap. When i worked in a collision shop i never used etch prime on bare metal on a newer car,just 2k, unless say i stripped a hood or roof then i would use it, but never on small areas.Now on restoration jobs i use it all the time. Its an easy step that is worth doing, especially on your own vehicle!!
 
Discussion starter · #10 ·
Thanks everyone....I am going to print out this topic and have a short meeting with the painter. He told me before that he WOULD etch prime if that is what I wanted, but, he and his tech rep did not see the ABSOLUTE need. Like you guys, I figure I am the customer and I should get WHAT I WANT....

Thanks again

Mike
 
#11 ·
self etch primer is not necessary with today's technology. In fact most paint manufacturers recomend against using self etch primer over blasted metal. You definately do not want to use self etch primer under any polyester filler because self etch primer is forever soluable. Use a catalyzed primer designed for use over bare steel, that way your filler work can be done over the top. Believe me I've tried it all and living in road salt country (Upper Peninsula of Michigan), I can guarantee for durability and corrosion resistance you are better off using a catalyzed primer such as epoxy. The key to success with any primer is having proper surface texture and cleanliness. Work Product Performance Auto Body
 
#12 ·
Bob, what about flash rust that forms in the time between blasting and priming?Epoxy is great but it will just cover the rust,not nuetralize it like etch will. And i'm sure you don't need to be told that rust starts to form as soon as the blasting is finished even if you don't see it.I have stripped a car that was blasted,then put in epoxy prime a short time after.Then it sat for a few years. I found a lot of surface rust under the epoxy. If you go with epoxy over the bare metal you should at least use a metal conditioner.
 
#13 ·
Agree with sevt_ We must be the rare production shop that uses it.
In fact the earlier primer surfacer (RM Diamont) required etch. Note: The etch is a conversion coating, do NOT apply for coverage, just a light dusting over exposed metal.
Diamont just modified one of their primer surfacers to eliminate the etch requirement.

Karl
 
#14 ·
Like i`ve stated I`ve been painting cars for 50 years. I have 8 cars in my collection, none of them had etching primer on them. I have painted thousands of cars (8 man shop )and never had a any trouble with paint.And I have won many paint awards.

I did not say the product was not a good one, I said I did`t use it very much.

I`ve never had a problem with "flash rust".

What ever the product, I go with ever works the best for me, not what the book says, but what I have used.

Troy-Curt
 
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#15 ·
I don't know where the paint companies are that don't "recommend" etch primers. There have been products popping up over the years that advertise "direct to metal" and of course the PPG marketing dept. did a super job on marketing their DP line of epoxies.

All of these products were developed and marketed to sell to people as an "alternative" to buying etch AND a 2K primer. It was a marketing tool to get the buyer who probably wouldn't use the etch anyway. If they can give him a Direct to metal product before the competitor comes in and shows him theirs, they make or keep a customer. It is ALWAYS marketed as a "cost saving" product because you don't need to buy the etch and you save labor costs by not applying two products. Go read the "benefits" or "product description" on the tech sheets or sales promo.

Now, after that, read the manufactures REQUIREMENTS, not recommendations but REQUIREMENTS on their life time warrantees. You will see etch primer EVERY time.


Even those "direct to metal" products will have recommendations for "maximum corrosion protection" to apply etch under them!! Some epoxies have warnings NOT to apply etch under them. Now, I would like the research dept. to tell me why. Epoxies are technically epoxies, period. Why would one recommend etch and another not? I'll tell you why, because the MARKETING DEPARTMENT says not to. They want a product to sell people on the idea that you don't need etch primer, PERIOD, in fact we recommend against it.

If you don't think the MARKETING dept. runs the show like that, you are sadly mistaken. As an example when I was repping we had two SS urethane top coats that where EXACTLY the same product with a different label on the can. One sold for $150.00 to $300.00 a gallon depending on color. The other sold for $100.00 a sprayable gallon, hardener and all ANY color. They were the EXACT same product!! They had a different label on the can, and were marketed to different "markets." The high end was marketed to OEM manufactures like VOLVO truck (and was used there) the other was marketed towards those guys with the logging trucks and places like that. The cheap one carried a two year warrantee in the "Fleet systems guide," while the expensive one carried a SEVEN year warrantee!! There were recommendations to "flatten" the "high" end product but NOT the "low" end product. The MARKETING dept. Did not want the "low" end product to be "as good" as the "high" end product.

Like I said, the marketing dept. runs the show. So this opens the door to another question. To play devils advocate here.
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Do the recommendations of etch primer in the life time warrantees come from the marketing dept. wanting to sell more product or the technical dept. wanting to protect the company with the best corrosion protection? I have my money on the technical dept. because that is what THEY told me.


Troycurt
Not using etch primer and saying "I have never needed it" is like saying "I have smoked and lived to be a hundred so smoking is good." It is something that a standard to which to test is needed. If you are doing award winning cars, I would have to assume you are not trying to keep logging trucks on the road on the coast of California. Things are a little different from show cars kept in a garage 350 days a year.

It depends greatly on the products you use also. When I started using etch primer I saw a big difference in how much better it adhered to the metal than the urethane primer. I could see if you sanded the urethane to bare metal with course paper like 120 that the grits of the paper would put a scratch to the bare metal and on the edge of that scratch it didn't seem like it was that well "stuck." The etch completely ended that. It may have been the products I was using, it may have been in my head. All I know is I have seen the testing done with etches Vs direct to metal and I will "waste the money and time" on the etch on every job.
 
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Discussion starter · #16 ·
Thanks for the input MARTINSR. I think I have a good basis for having the painter put on the etch first. This is turning into a "money is no object" project for the time being, so I will have the etch done first.

In your experience, can I leave the etch uncoated until the body comes back from the sheetmetal shop. I intend to have the sheetmetal done after the blasting and etch prime, then bring the car home and finness the body "to perfection", then do the final priming and blocking before paint. I know I have to take off the etch in the areas that require any filler work..

Thanks to all for your input...it helps a lot to get the opinions from all of you..

Mike
 
#17 ·
I agree self etching primer is a good product for some situations, but it is not suitable for me. It is forever soluable. And PPG does not recomend it's use over BLASTED steel-------check with your paint reps! I have NEVER had any durability or corrosion problems using epoxy primers and have backed it up with my own saltwater testing! I've also done my own saltwater testing on weld through primers and you would be surprised which ones work and the others that are junk. Also with the amount of solvent in self etching primer shrinking is also a concern. Heck even Boyd Coddington recomends and uses epoxy. You do not want to put a soluable product under any catalyzed surfacer period. ttt
 
#19 ·
Am a FACT kinda person, so I looked throu my tech sheets and repair guide lines I have right here at home. I have PPG, Dupont, S-W and Valspar. All are pretty current PPG is 1year old, Dupont is 4-5, S-W is 2years and Valspar is 1year.

Now Bob, NOWHERE did I find any mention of etch not to be used on sand blasted steel, in either tech sheets or repair guide and not just in PPG. The only comapny that said not to use etch on blasted steel was Valspar. Now when I talked with the REP not just some idiot behind the counter, the reason they stat not for use on blasted steel is because to many people use the etch as a stand alone primer. You know I know when you blast something you have huge pits, well that etch doesnt have enough film build to cover up all that surface area of the pits. Then people come back and paint right over the etch. Now on certain spots all you have protecting the metal is a TOPCOAT. THATS WHY ITS NOT RECOMMENDED ON BLASTED STEEL NOT CAUSE IT DOESNT WORK

And I will ask the PPG rep this Thursdsay when he stops by, trust me on that.

Now since I like facts I thought I would copy some info off the tech sheets, lets see what they say!!!
All right first is from my M-S tech sheet same as S-W just diff label. Notice on bottom it clearly stats the use of etch primer on bare steel, filler and old paint. For what reason? To achieve max adhesion and corrosion resistance
http://www.chevelles.com/showroom/msetch1.jpg

This is one of PPG's oh so famous DTM primers that claim to rid of the etching step. But look at the surface prep section, notice it says for max performance the use of metal treatsments or a wash/etch is to be used.
http://www.chevelles.com/showroom/PPGNCP.jpg

Ok Bob, etch not to be used on blasted steel, HELL ask the reps. Then look at this. See on DPLF an epoxy primer, it stats if 1.5-2.0 mils is required or the USE OF METAL TREATMENTS OR DX1791 MUST BE USED,thats on blasted steel. So tell me why its etch not to be used on blasted steel?? Plus on surface prep it clearly stats once again for max performance a metal treatment or wash/etch primer should be used.
http://www.chevelles.com/showroom/ppgepoxy1.jpg

Duponts lifetime warrenty guideline sheets. What do i see on the lifetime warrenty, its etch primer(variprime). Not epoxy or DTM its plane and simple etch. Dupont's epoxy is prime-seal that shows up on the 7 year warrenty, why use something that dupont clearly shows is a lesser pretreatment.
http://www.chevelles.com/showroom/dupontetch.jpg

Duponts tech sheet on epoxy. Again for max performacne the use of etch is to be used
http://www.chevelles.com/showroom/dupontepoxy1.jpg

Right from the PPG website on how to treat rust
http://www.ppg.com/cr-refinish/phase1/frmShowDefect.asp?LanguageId=4&IntDialCode=44&ProcessStage=0&ShowPicture=0&DefectId=88

All of this is nothing more then plan and simple FACTS right from the tech sheets, not just some BS that I thought of. The tech sheets speak for themselves.

AWWW man just re-read that BOYD Coddington uses epoxy not etch. Sh!t nevermind guys I take it all back, throw out the etch and buy epoxy...Eric
 
#20 ·
I don`t paint just show cars.I have two employes and my self doing custom and restoration work,I have six employes doing nothing but insurance and general body and paint work. I`m sure the etch works as good as you say it does.I have most every paint co. tech sheets.I have painted with and without etch and can not see any difference in the end results.A person should use what ever makes them comfortable, and works for them.

If I was working on a car with rust problems under the paint and a pitted situation that I could not blast out completely then I would probabley use the etch. In that situation I have been using corraless (not sure of the spelling)
a product of Eastwood Co.Seems to work real good.

Like I`ve posted befor, I`m not saying my way is the way to do it. Just that it workes for me.
Have a nice day.

Troy-Curt:
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