Epoxy primer query

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PostPosted: Thu Jan 13, 2022 1:37 am
Hi

Hoping someone could clear some things up for me.

I have a restoration project that is a long term project and I originally planned on doing the body work one panel at a time and then put it in epoxy primer while I work on the rest.

I have been reading about the chemical bond the epoxy has with top coatings when it is applied within the recoat window. Whereas if you let the epoxy cure / miss the window, you have to re sand it and only get a mechanical bond.

My questions are:

a) if i decide to apply epoxy on a panel and leave it for months, when it comes time to continue on the panel, can I re sand it and apply a fresh single coat of epoxy and still achieve both the chemical and mechanical bond if I put the top coat within the recoat window?

b) The 3M platinum plus body filler TDS says it can be applied over fully cured epoxy. I'm confused because it seems like I have to let the epoxy fully cure anyway if I plan to put body filler over it...or is it the same as question a) in that I put another coat of epoxy over the original epoxy and body filler once done to get the chemical / mechanical bond for the next coats?

Appreciate any help.

Adam

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PostPosted: Thu Jan 13, 2022 11:04 am
a) if i decide to apply epoxy on a panel and leave it for months, when it comes time to continue on the panel, can I re sand it and apply a fresh single coat of epoxy and still achieve both the chemical and mechanical bond if I put the top coat within the recoat window?

Correct, if you epoxy and let it sit, sand it and do a wet on wet application.

epoxy, flash, basecoat/single stage


b) The 3M platinum plus body filler TDS says it can be applied over fully cured epoxy. I'm confused because it seems like I have to let the epoxy fully cure anyway if I plan to put body filler over it...or is it the same as question a) in that I put another coat of epoxy over the original epoxy and body filler once done to get the chemical / mechanical bond for the next coats?

i would not go so much off the filler tech sheet, i would pay more attention to the epoxy TDS. what epoxy do you plan to use ?
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PostPosted: Thu Jan 13, 2022 11:40 am
I use the 3M Platinum (not the plus) over epoxy all the time.
My epoxy has a 7 day top coat window in which the filler can be applied without sanding.
Like Dave said, you need to read the technical data sheet for your products.

Generally, I shoot 2 coats of epoxy on bare metal, wait at least 24 hours and then lightly block sand to reveal any low spots on the panel. Apply my filler and block sand, feathering filling into surrounding epoxy.

Once filler work is done, like Dave said, you should sand it and shoot another coat of epoxy.
If you are happy with what you see, move on. If you are not happy with what you see, shoot some 2k build primer and begin the guide coat, block sanding process.
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PostPosted: Thu Jan 13, 2022 12:36 pm
'68 Coronet R/T wrote:I use the 3M Platinum (not the plus) over epoxy all the time.
My epoxy has a 7 day top coat window in which the filler can be applied without sanding.
Like Dave said, you need to read the technical data sheet for your products.

Generally, I shoot 2 coats of epoxy on bare metal, wait at least 24 hours and then lightly block sand to reveal any low spots on the panel. Apply my filler and block sand, feathering filling into surrounding epoxy.

Once filler work is done, like Dave said, you should sand it and shoot another coat of epoxy.
If you are happy with what you see, move on. If you are not happy with what you see, shoot some 2k build primer and begin the guide coat, block sanding process.



Great added on info
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