Interesting epoxy test.

Barry

Barry

Paint Fanatic
Staff member
Now here is an interesting test of the black epoxy fresh out of the salt-spray cabinet after 40.5 days.

Same thing but panel on left has one more mil of epoxy at about 3.2 miles and panel one right has about 2 mils.

Where the scribe mark down the center is you can see, just a little more creeping under the epoxy with the less mils, minor but good to know.

Now notice the solid coat of the epoxy is unaffected with either one, still nice and black but i do show a white refection but that is from my cell phone.

This was an abusive test and would be about the same as driving your car in the ocean every day but all good to know.

Moral of story?? Three wet coats on a frame and maybe three wet coats on the body-shell?? but that is your call. 130605_0003.jpg
 
Do the same test with self etch primer even coated with a urethane and there probably wouldn't have been any left on the panel.
 
Barry, would it make much of a difference if the 3rd coat was applied at a later date? I am definitely going to hit the underside of my car with three coats, but I have the rear quarters, decklid, and roof shot with 2. After seeing how awesome that it I was thinking of hitting them with a 3rd :)
 
Raymond_B;28732 said:
Barry, would it make much of a difference if the 3rd coat was applied at a later date? I am definitely going to hit the underside of my car with three coats, but I have the rear quarters, decklid, and roof shot with 2. After seeing how awesome that it I was thinking of hitting them with a 3rd :)
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Not a bit, mils is the important thing.
 
Bob Hollinshead;28730 said:
Do the same test with self etch primer even coated with a urethane and there probably wouldn't have been any left on the panel.
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Bob,
Funny you should mention that, here is a panel done at same time with just 6520 regular build primer over bare metal, actually is was taken out half way through the test as it looked so bad, so it was exposed close to 30% of the time of the epoxy.

I know when some of you folks call me and say, ready to paint but I have some little bare metal spots I sanded through what to do and I say hit with epoxy and you don't want to hear that because of the extra work, this is why.130606_0001.jpg
 
This was a real abusive test with a 8 times salt rate normally used for normal standard test as I was testing for a specific thing but the mil rate difference was accidental and something I noticed right away.

Funny how an "off the chart test" when you are fooling around can give you the best education.
 
Wow. Just wow. Great thread. Dub needs to "sticky" this
 
How does the turbo primer hold up barry?

The center strip thats rusting on all three.. Is that where the salt is sprayed or was that a scribe made prior to going into the spray tank..

No idea how this works.
 
Chad, the scrub is done with a flat head screw driver, salt water mist is sprayed over the whole panel non stop.
So intense the scribe will rust within ten minutes of exposure, then you measure creep-age, under the epoxy weekly.

As you can see the epoxy that is whole is not affected and would take moons to cause a problem, where as the primer, it goes through.

Turbo should test a little better and as I have time in next month, I will try to do a comparison test, never have and may not be a real big difference but some, this is why you don't drive a car in urethane primer.
 
When I worked at SW they recommended applying a coat of self etch primer. Then 2-3 coats of epoxy for "best protection". What is your take on this when using SPI epoxy? Good idea? Waste of time? Any benefit?
Rob Dumais
 
The tech sheet is pretty clear on this issue:

NEVER use SPI Epoxy over Acid Etch/Wash Primers or Rust Converters. It will not work and we strongly suggest if you want to use a rust converter that you use the rust converters paint system instead of SPI.
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streamlinecollision;29158 said:
When I worked at SW they recommended applying a coat of self etch primer. Then 2-3 coats of epoxy for "best protection". What is your take on this when using SPI epoxy? Good idea? Waste of time? Any benefit?
Rob Dumais
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PPG at one point also recommend that for the LF epoxy I don't know if it was to sell more product or if it was because at that time, there seemed to be metal adhesion problems.
Bottom line it is a waste of money and not a favorable foundation for long term.
 
Ready for paint ?

Barry;28737 said:
Bob,
Funny you should mention that, here is a panel done at same time with just 6520 regular build primer over bare metal, actually is was taken out half way through the test as it looked so bad, so it was exposed close to 30% of the time of the epoxy.

I know when some of you folks call me and say, ready to paint but I have some little bare metal spots I sanded through what to do and I say hit with epoxy and you don't want to hear that because of the extra work, this is why.
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I am ready to wet sand before my epoxy sealer. And yes, I do have some little bare metal spots. If the original bare shell needed 80 grit scratches, will the epoxy stick to these small spots ? James A. told me earlier to spray my epoxy sealer without reducing it , which I plan on doing.

How about spot putty on the sanded 2k ? I'm talking small areas (spots) on the 2k that was sprayed a couple of weeks ago. Will these be ok with just the sealer ?

This is my first project and I am grateful I found your website.
 
Just my own rule but on sand throughs showing bare metal spots the size of a quarter or smaller I don't worry about roughing them up with a coarse grit. I'd reduce the sealer for it to go on better. And any polyester putty spots need to be primed and sanded before sealer IMO.
 
I almost want to make a few panels to mount outside the store.. maybe on the side of the building.. One in etch primer and one in epoxy.. I have so many people that come in wanting to use etch primer... It wouldn't take long with just sitting outside to use as a good example.
 
To tell the truth, 2K etch primer works pretty well when used in a system with urethane primer and paint. It can be fairly resistant to creep because of the chromate conversion. The big problem comes when plastic filler on metal is added to the mix. Self-etch can't do anything to improve the corrosion resistance of filler on steel. Your etch test panel should include a filled dent in the center of each panel, one filled over bare metal and etch primered, and one filled over epoxy. Both painted normally, then put a big scratch down the middle and wait.
 
Seeing these test pieces.....am I safe to assume that I can finish the bodywork on my dd one panel at a time while I continue to drive the truck as long as I cover the finished work with spi epoxy primer?
 
Lou;30590 said:
Seeing these test pieces.....am I safe to assume that I can finish the bodywork on my dd one panel at a time while I continue to drive the truck as long as I cover the finished work with spi epoxy primer?
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Absolutely, this is a great way to do a "rolling restoration."
 
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