When to use epoxy primer as a sealer?

Schroeder

Schroeder

Promoted Users
I'm not really sure what the application of epoxy "as a sealer" is. I've painted a couple coats on the inside of some stuff that hopefully never sees the light of day again. This includes the inside of the brook skin and inside of the cowl panels. Should I reduce some epoxy primer and spray it as a sealer over the epoxy primer? What are the benefits of this? What are the general applications?
 
Dean Jenkins

Dean Jenkins

Promoted Users
Just when I think I know what I'm talking about and answer a question like this, I find out how much I don't know when other more experienced folks chime in.
I think I know the answer, but take it with the "sort of still newbie, backyard hack" disclaimer.

If you've put down good coats of epoxy on areas that will not be seen, or the goal is just preservation and/or OEM style appearance for inner panels, and the color/sheen is what you want, then you are done.

Sealer (which is usually reduced epoxy) is for a last coat over prior (cured) epoxy or filler/2K primer/exposed bare metal/poly primer. It "seals" all that stuff before you apply single stage or base coat paint. This provides a great, uniform material for the next stage, with great chemical and mechanical adhesion to both what it is sprayed over, and for the material sprayed on it.
If shooting over cured epoxy, or 2K that is more than a few says old, then that needs to be scuffed before shooting sealer.

I think that is right, but others may offer better advice.
 
Chris_Hamilton

Chris_Hamilton

Trying to be the best me, I can be
The purpose of a sealer is to provide a uniform coat (all the same color) over what is to be painted as well as an adhesion "bridge" to allow base or SS to adhere to a cured substrate like cured epoxy or OEM primer or EDP.
If you are using epoxy as your primer and it's out of the 7 day window then you need to seal it with more epoxy (reduced) to ensure adhesion.
 
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Schroeder

Schroeder

Promoted Users
Thanks guys. Is the sealer not needed though I thought a lot of guys here put epoxy down, did their filler and body work, and then shot a last coat of epoxy again. Is this last coat just regular epoxy or is this the sealer coat and it's always just been implicit knowledge here among you painting masters when I see discussion of that final coat?
 
Chris_Hamilton

Chris_Hamilton

Trying to be the best me, I can be
Schroeder said:
Thanks guys. Is the sealer not needed though I thought a lot of guys here put epoxy down, did their filler and body work, and then shot a last coat of epoxy again. Is this last coat just regular epoxy or is this the sealer coat and it's always just been implicit knowledge here among you painting masters when I see discussion of that final coat?
Click to expand...
If you do what you described, the epoxy needs to be sanded and within the 7 day window for best results (adhesion mainly) when going over it directly with base or SS. You would sand to eliminate texture. It's not sealer but serves the same purpose doing it this way, Easier to spray it as a sealer prior to base or SS. Most of us seal before shooting color. Stuff that is never going to be seen IMO not as critical but you still want it to stick so if shooting over cured/old epoxy then you would want to seal it.
Don't overthink it. Prep the body, mask, degrease, seal, base, then clear, or SS.
 
Schroeder

Schroeder

Promoted Users
Chris_Hamilton said:
If you do what you described, the epoxy needs to be sanded and within the 7 day window for best results (adhesion mainly) when going over it directly with base or SS. You would sand to eliminate texture. It's not sealer but serves the same purpose doing it this way, Easier to spray it as a sealer prior to base or SS. Most of us seal before shooting color. Stuff that is never going to be seen IMO not as critical but you still want it to stick so if shooting over cured/old epoxy then you would want to seal it.
Don't overthink it. Prep the body, mask, degrease, seal, base, then clear, or SS.
Click to expand...
Got it. Thanks guys.
 
Lizer

Lizer

Mad Scientist
I shoot final coat of epoxy unreduced and then wet sand 600 to create a perfectly smooth and nib free peel free substrate.
 
jcclark

jcclark

Oldtimer
I only tried a dedicated sealer once and the directions for that one said
wait an hour before base coating over so I thought why should I switch to it, I'll
just keep on using a sealer coat of epoxy like I have for the last 25 yrs.
 
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