Last year I stripped most of the body of my 67 Malibu and painted the bare metal with Variprime 615S and 620S self etching primer and activator. Now I'm throwing down a little filler on some low spots. I'm finding that when I sand the self etching primer away in spots as I feather edge, I'm seeing tiny rust pits and small rust spots.

Question #1: What's going on? I was told that the self etching primer would prevent rust. I was very meticulous about removing all the rust before I applied the Variprime. The car sat in the garage all year since I started working on it, so it hasn't really been exposed to the weather. It may have gotten sprinkled on once.

Question #2: What do you do about the tiny rust pits? Are they actually already neutralized because of the self etching primer? If I sandblast or apply a metal prep, I'll be loosing my filler.

Thanks!
Mike

If there are rust spots under your primer you didn't prep the surface correctly before spraying your primer or its so rusted out that its coming in from the back side of the metal. I doubt the later. Did you use a metal conditioner before spraying your primer? I would DA it down to steel again, use metal conditioner, and reprime. Your other option, IMHO, is to not do anything and continue on with the paint job only to see it self destruck in a year or two when those little rust spots turn into quarter sized rust zits.

1. It is not insoluable. I had a problem with it once myself where I didn't have enough on and the car got wet, same results.

If the film is too thin, it just isn't going to protect as it was designed. It did get wet remember.

Do NOT use a metal condtioner unless it says so in the tech sheets. The acid in the etch primer will attack the phosphoric coating left on the surface by SOME condidtioners and you will LOOSE adhesion.

2.The rust WAS nutralized when you sprayed the etch if it was small. Any rust that forms now, it is not going to be because the acid has long gone when the primer flashed off.
It is so hard to say what exactly you are seeing. It could be "remnants" of the rust that was there before the priming. Or it could be new, I sure can't say. If it is new, you need to sand this primer off and reapply.

Originally posted by 67shovel:
If there are rust spots under your primer you didn't prep the surface correctly before spraying your primer or its so rusted out that its coming in from the back side of the metal. I doubt the later. Did you use a metal conditioner before spraying your primer? I would DA it down to steel again, use metal conditioner, and reprime. Your other option, IMHO, is to not do anything and continue on with the paint job only to see it self destruck in a year or two when those little rust spots turn into quarter sized rust zits. Thanks for the reply. I was very careful to remove all the rust. I talked to the body shop supply store owner and used the metal conditioner that he recommended before I applied the primer. I bit the bullet and sand blasted it again. :(

Originally posted by MARTINSR:
1. It is not insoluable. I had a problem with it once myself where I didn't have enough on and the car got wet, same results.

If the film is too thin, it just isn't going to protect as it was designed. It did get wet remember.

Do NOT use a metal condtioner unless it says so in the tech sheets. The acid in the etch primer will attack the phosphoric coating left on the surface by SOME condidtioners and you will LOOSE adhesion.

2.The rust WAS nutralized when you sprayed the etch if it was small. Any rust that forms now, it is not going to be because the acid has long gone when the primer flashed off.
It is so hard to say what exactly you are seeing. It could be "remnants" of the rust that was there before the priming. Or it could be new, I sure can't say. If it is new, you need to sand this primer off and reapply. Thanks for the information. I'm puzzled. Next time rather than listen to the store owner only, I'll get the tech sheets that you mentioned as well.

Are you familiar with the Dupont Variprime self etch primer?

Mike

I am!!
In my opinion its one of the best if not THE best etches out there.
What you want to know about it?...Eric

It comes or did come in two different types. One containing lead and chromate the other without. If its avaible in your area opt for 615S which has the lead and chromate, its better then the one without.

The recommended surface grit prep is 180-220
Two coats is recommeded so apply 2 med coats. It has a flash time of 5 mins or when dull.
Allow 45 mins flash time before appling a primer surfacer or sealer.
After 24hrs variprime MUST be sanded.
For best results prime within 16hrs.

If you cant see throu the variprime and see metal then you applied too heavy. When you do this you can also loose adhesion. Wait for the variprime to dry then scuff sand it real lightly with a red scuff pad to remove some of that primer, then continue on with primer surfacer or sealer.

What ever you do DONT use a metal cleaner or conditioner prior to variprime. Been down that road once before graemlins/thumbsup.gif :rolleyes:

also, don't every apply topcoat directly to variprime, it must be primed or sealed before topcoating. I used dupont chroma and chroma premier products exclusively for 3 years. I haven't ever seen an adhesion problem using variprime but I also haven't seen any real benifits either. It is a soluable product that is very suseptable to solvent absorbtion and that is why direct topcoating is not recomended. The solvents will be absorbed then released through the topcoat causing adhesion problems.

I'll bet a dollar the "conditioner" is the cause of all this. First off, no conditioner is needed, the etch does all that. Second, if a "conditioner" is used which left a phosphoric coating on the metal, the acid in the Variprime attacted it INSTEAD of attacking the metal and you lost adhesion.
Third, and a REAL possiblility, the "conditioner" application used a water rinse and you didn't do it properly and started flash rusting INSTANTLY before you "covered it up" with the variprime.

Etch primer does work, I have seen some pretty convincing tests done. It does it's job.

I'll ask this also, maybe I've been mis-informed ... I thought etch primer needed either epoxy primer or sealer applied to prevent moisture absorbtion. I thought without one of these applied, primer itself was about like a sponge.

Thanks, Neal

Guys,

Really appreciate the feedback. Apparently, the problem was my using a metal conditioner prior to priming.

MARTINSR - You mentioned the possibility of not doing the water rinse correctly. What exactly should I have done?

Thanks!

Mike

Neal...your right , Variprime is just and etch-primer and needs to be over coated with a Epoxy,2K or sealer..with in 24 hours or you need to re sand...the surface.

Wait a minute.....I thought that self etching was epoxy primer. :eek:

I was led to believe by the body shop supply counterman that once I applied the Vari-prime self etch that it would be protected from rust till I could get around to finishing the project. :confused: Was I led astray?

Mike

Yes, you were led astray. All info I've dug up while preparing for my own projects is that etch will kill the microscopic rust and eat into the metal, but it MUST be epoxied over since it is NOT a 'solid' surface, it's porus and WILL allow moisture (read: Oxygen) to reach the metal ruining all your work. Once it's flashed (see above), epoxy prime it for a long lasting durable base.

AFAIK this goes for all quality etch primers. They work great when used in this manner.

Something in the tech sheet that caught my eye.

Tips for Success:
Keep cans closed when not in use to prevent moisture aborption, which may lead to blistering, loss of adhesion and other product failures.

If you primed the car at differnet times and the can wasnt sealed right...well its a possiblity

As for the metal treatment what product did you use? The metal treatment is a two step process using metal conditioner 5717S First then follow that up with the conversion coating 5718S.

The conditioner 5717S is a cleaner it chemcially cleans the surface. 5718S is a conversion coating that coats the metal with the zinc coating.
You mix it in a ratio of 1part 5717S to 2parts water. Apply the mixture with a brush keeping the surface wet, also scrub the metal with a scuff pad.
Rinse surface off with clean water, if the water beads up you need to reapply MORE 5717S and continue to scuff til the water SHEETS off the surface.

5718S is applied straight up NO water. Scuff surface with scuff pad keeping surface wet with 5718S. After scuffing for a few mins rinse off with clean water. Once again you want the water to sheet off not bead up. If you get ANY beading reapply more 5718S til water sheets off.

If you didnt follow 5717S up with 5718S basically all you did was clean the surface and invite rust to form with the water.

Like Martin mentioned since etch and metal treatments dont see eye to eye they fought each other.

Am a etch primer fan on bare metal. Ive had epoxy bite me a few times, stopped using it on bare metal no more problems.
Etch primer is not meant to be a one step primer or stand alone product just like epoxy it needs to be topcoated with the proper products to achieve good lasting results.

Each product has its pro's and con's, if variprime wasnt a good quality product Dupont wouldnt list it for the lifetime warranty. Same goes for epoxy if it was junk and didnt preform it wouldnt be listed.

sevt_chevelle,

Thanks for that information. I don't have the tech sheets, but I do have the Dupont handbook. They don't provide the detail you provided.

When I applied the variprime, the can was new.

You mentioned that you don't like epoxy products over bare metal. What would you apply over the Variprime to protect the panels until you can finish the project? Is there a specific Dupont primer that you can recommend? I do have some Dupont Enamel non sanding primer, but it says to only topcoat with enamel. I think I'll be needing to use a high build laquer primer at one point in the project. Would it be okay to cover the enamel primer with the conventional laquer high build primer if I use it? I like to only work on 1-2 panels at a time. I'm kind of slow. redface.gif

Mike

You want to use a urethane primer over the etch like Uroprime.

The enamel sealer and lacquer "high build" primer are for trailers, and ones you don't care about to boot.

First off, the "High build" lacquer primers have about as much solids as first generation urethanes (twenty years ago at least). The urethanes of late are FAR more filling than lacquer with little to no shrinking if used correctly.

Using either one of these products under your paint would be like putting a layer of mud over your houses contrete foundation before starting to build the house.

Stick with 2K products like epoxy, urethane and the like which use a hardener.

I'll try the Uroprime. If I was starting the project over, I'd go with all the latest stuff. I'm about 80% done now though. :(

No doubt that you are right about the 2k products, but I had already bought all my materials. I have to use what I have if at all possible. Now I'm regretting that I allowed the store owner to talk me in to buying the etch!

This is probably my last project. That's why I would rather stick with what I know as far as possible. Don't want to have to buy a new paint gun...... I learned how to paint back in the 1980's when it was Acylic Enamel over a laquer high build primer. Probably painted 20 cars back then, they turned out great, looked better than what came out of many body shops, never had rust come back. So this is one last job for the old Devilbus 502 JGA gun. ;)

So, I guess I don't need the latest paint technology here, just need to wrap this thing up with out having any catastrophic chemical reactions/incompatability.

Mike

Pennybags, even thou am a PPG user and fan I used Dupont for a few years and really do miss some of those dupont products.
I miss the variprime and Uroprime, its one hard combo to beat in my book.

I havent sprayed a Dupont product since I moved back to Iowa in Aug of 1999, products have changed and to be honest I dont know and cant recommended what epoxy dupont has to offer.

I prefer etch on bare metal vs epoxy, but NEVER said or think epoxy is a junk product. It fact I think its a great product, just that I believe etch is superior on bare metal then epoxy.

I like you are VERY slow at working on this stuff. Ive got a fan shroud off a 38 farmall that Ive been working on. FaN came loose and tore a 3-4in tear in the metal. I started welding on it right around thanksgiving and YET to get it done.

Because am slow at it I strip the metal then apply my etch primer then come back and apply 2 coats of epoxy. I do this because I can then apply filler over the epoxy and plus I think epoxy is a tad more resistant to the elements then a urethane primer surfacer.

Anyway thats what I do its my method it works for me. If you just apply your variprime and uroprime thats a great method too, nothing wrong with it.

You shouldnt be regreting buy the etch, should be regreting letting him talk you into applying the metal treatment first then the etch.

I agree with Martin on this, its was the metal treatment followed with the etch that killed ya. Ive got spare parts for my 72 truck in just variprime that look good as the day I sprayed them probably 6 yrs ago. Same with some parts for the velle sitting in PPG's etch look great also once again probably 3-4yrs old

sevt_chevelle,

Thanks for the insight. I bit the bullet and bought some Corlar Epoxy primer 824S/826S. Couldn't swing for the URO-Primer ($$$$!!!)

I hear you on the slow. I finished my degree last year. Took a lot of time.

Have to tap your brain again as I'm a little tweaked and confused about my body shop supply store experience. When I bought my stuff a year or so ago, the counterman recommended I go Variprime Self-etch (615s) >Fill'n Sand (131S) > Non Sanding enamel primer-Sealer (1858S)> Dupont Cenatri Enamel top coat. Now mind you, I'm about 80% done - both doors, front fenders, hood, roof, and rear decklid are perfect. On the panels that I've finished I had applied Variprime etch, used my filler, then followed by some 131S Acrylic Primer Surfacer. When I picked up the Corlar, a different counterman told me that I shouldn't have used the 131S over the Variprime self etch if I want to spray enamel non sanding primer or Centari topcoat!!!! Do I have to strip everything off? :eek:

Mike

We didnt use fill-n-sand all that much just old lacquer technology, we used the Uroprime.
In the tech sheet for 131S it says:
For bare metal apply 2 coats of variprime OR treat steel with 5717S/5718S, then apply 131S

So YES you can apply your 131S over variprime.

Originally posted by sevt_chevelle:
We didnt use fill-n-sand all that much just old lacquer technology, we used the Uroprime.
In the tech sheet for 131S it says:
For bare metal apply 2 coats of variprime OR treat steel with 5717S/5718S, then apply 131S

So YES you can apply your 131S over variprime. Wow! What a relief! Even if the 131S is topcoated with an enamel?

Have to ask you two last (hopefully) :D questions. They told me today to use mix the activator and the Corlar, then add thinner. They said that I could use the same one that I use with the 131S. It seemed to spray fine, but I'm seeing in my book now that I should have used a reducer, not a thinner. Do I have to strip the Corlar now?

How did you find these tech sheets? They said they didn't have any. Be a darn good thing to have.

Mike

just for future reference Dupont 2580CR is a "Direct to Metal" Chromate Epoxy that I use and like as much as 615S

and you can get any of the newer Dupont tech sheets from here http://www.performancecoatings.dupont.com/ just click on the "visitor" tab and have a look around

Thanks for the link! I had a look around. Could not get the sheets to load. I'll try on the computer at work.

Mike

Your jobber should be ashamed of themselves to not have tech sheets for thier customers!! You tell them that for me!

I can tell you this, there isn't a person in the darn building who has been to tech school or they would have the darn things there!

I would be looking for a new jobber.

Thinning Corlar with Laquer thinner doesn't sound right to me, you should definately get the tech sheet for any materials you're using. The support at your paint store sounds weak. Years ago (20) it was common practice to use 131S over Variprime but now better materials are available.

Bottom line, since I used laquer thinner instead of the proper reducer to thin the mixed Corlar/activator mixture 20%, does it NEED to come off?

I'd find a new jobber, but it's mostly PPG up here. He's the only Dupont jobber in the area AFAIK.

Thanks!

Mike

about the sheets not loading...you need adobe acrobat reader to view them if you don't have it or have an old version you can pick up the new ones here http://www.adobe.com/products/acrobat/readstep2.html

I have no experience with corlar so I can't help there sorry