Pre epoxy metal prep

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PostPosted: Tue Jan 25, 2022 9:17 am
What do you gents use for metal prep prior to epoxy? The last time I did any bare metal work was 20 years ago, with the exception of aluminum, which we use alodine for.
Some is blasted, some is wheel stripped, my concern is the micro rust in the pits I can't see. Most epoxy I've known about is dtm to blasted steel, this isn't 100% blasted.
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PostPosted: Tue Jan 25, 2022 10:48 am
DA the metal with 80 grit.

Mix your epoxy part A and B and let that induce while you clean the metal

Wipe down with automotive Wax and Grease Remover. I put some into a spray bottle and have a roll of blue shop towels handy. Spray the W&G on the panel and BEFORE it drys, wipe it off with a shop towel. Repeat the process for the entire vehicle.

The W&G wiped panels should be ready to spray in as little as 15 minutes if the metal temp is well above 70 degrees. You can spray it with compressed air to see that it is completely flashed off or wait 30 minutes or so.

Shoot your first coat of epoxy primer and let it flash (read tech sheet) and then follow with another coat and let that set at least 24 hours at 70 plus degrees.
1968 Coronet R/T


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PostPosted: Tue Jan 25, 2022 12:01 pm
:goodpost: i would do this at least 2 times if not 3 it needs to be clean, cloth or paper should be clean after you use it.
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PostPosted: Fri Jan 28, 2022 7:28 am
I totally get it I use that same process. What I'm eluding to is treating the areas the sanding can't get to. I have spots with small pitting and very light rust. I'm concerned the epoxy won't be enough to keep it at bay. I'm looking at an acid cleaner and conditioner in order to convert those areas and neutralize them before the epoxy. Is this something you've done? Or will it negatively affect the epoxies grip?
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PostPosted: Fri Jan 28, 2022 7:10 pm
Rsrguy3 wrote: Is this something you've done? Or will it negatively affect the epoxies grip?


I did a few day courses with a very reputable paint place. All bare metal was cleaned with phosphoric acid and a scotchbrite. Then washed down with water. Don't use soap and water as soap will leave an oily residue. The phosphoric acid makes it less likely to rust and to a small extent dissolves small (microscopic) bit of rust. It doesn't leave it in an acid state that need to be neutralized. Then it's epoxy primered over.

I'm sure others have their own own opinions on the subject. This is what they taught us on the course.



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PostPosted: Sat Jan 29, 2022 8:01 am
I ended up using the one choice yesterday. I completely cleaned the steel until the towels came up clean, then scotch brited the first stage, rinsed then applied the conditioner to the dried surface, rinsed and towel dried, then wiped several times with acetone until the surface gave me clean prep towels. I'm pretty sure it's good, the cre laid down well.
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PostPosted: Sat Jan 29, 2022 4:47 pm
Looking good!

Excellent work space - I'm jealous :worthy:



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PostPosted: Sat Jan 29, 2022 6:01 pm
My brother's hangar.
Treated the small pit rust on the roof today, used rust mort.
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PostPosted: Sat Jan 29, 2022 9:21 pm
Bill911 wrote:
Rsrguy3 wrote: Is this something you've done? Or will it negatively affect the epoxies grip?


I did a few day courses with a very reputable paint place. All bare metal was cleaned with phosphoric acid and a scotchbrite. Then washed down with water. Don't use soap and water as soap will leave an oily residue. The phosphoric acid makes it less likely to rust and to a small extent dissolves small (microscopic) bit of rust. It doesn't leave it in an acid state that need to be neutralized. Then it's epoxy primered over.

I'm sure others have their own own opinions on the subject. This is what they taught us on the course.


I disagree with this.
Phosphoric acid DOES leave a film and actually turns white if is not properly neutralized.

Personal experience in having to strip the roof on my signature car trumps anything the manufacturer may claim.

I personally still use Phosphoric acid BUT I am very careful to properly neutralize it prior to painting. The steps to neutralize are simple. After you have converted all the rust, you wet an area thoroughly with the Phosphoric acid and while it's still wet, wash it off with soap and water using a Scotchbrite pad. Rinse thoroughly with clean water and then blow dry with compressed air.

After it has set for a bit, wipe it down with Wax and Grease remover, spray on, wipe off before it dries method.

Once flashed off, you are ready for epoxy primer and it will be properly protected for life.

I have done it this way for years now with absolutely no issues. My projects with numerous pictures are posted in that section on this forum. They are not just freshly painted parts anymore, they have stood the test of time for years.
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PostPosted: Sat Jan 29, 2022 11:43 pm
Yes, similar for me, I chase the white film and the sticky residue until it's thoroughly gone. The water base degreaser I use is quite sudsy and I scrub it thoroughly with scotchbright. Then I rinse with clean water and towel dry. Then w&g, then wipe vigorously with acetone until the prep towel is clean... I do alot of alodine, similar techniques there.

It's been ages since I'd done this much naked steel.. Before epoxy. Anyway my issue was the adamant suggestions that I needed to go straight to epoxy after blasting, for me an issue, as some areas could not be blasted. Bottom line I'm comfortable with the concensus from you gents that old school acid when properly applied and neutralized is compatible with epoxy.
Thank you
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