Epoxy outside recoat window

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SEOK

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Im working on a big car in my spare time and have to do it in sections as time allows. This causes me to be outside the Epoxy recoat window A LOT and im a little confused at a certain stage...

I have my front clip finished (metal, filler, poly etc) and in two coats of SPI epoxy to protect it. I chose to epoxy them now because the car does and will be outside occasionally while i work on other things.
I planned on using the epoxy as a sealer when it comes time to paint and Im understanding that epoxy outside the recoat window should be sanded with 180 for a proper mech bond and recoated.
My question is--- since its in cured epoxy now, when it comes time to base would i still need to sand with 180 for a coat of epoxy sealer? if so, wouldnt the 180 scratches show through the thin sealer? or use higher grit? or no need for sealer since its in epoxy now? or is it better to shoot an unreduced coat to fill them in? im really confused here and dont want to ruin something or take any unnecessary steps.
-what would you suggest the steps would be with fully cured epoxy prepping for paint?
 
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1A Rock said:
What was the work sanded to at this step?
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finished in 180 then a lighter pass with 220 and shot 2 coats of unreduced Epoxy. Left as is, its been about 3 weeks now. I had a few small spots of trash that i was going to scuff out and shoot one more coat within the 7 day window but that was never able to happen as i had to take care of other work on the car. I figure they would just get cleaned up when i prep for sealer (or whatever is suggested here)
 
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I've left epoxy sitting 6-8 months before. Just sand with 180 , spray couple more coats epoxy and keep on truckin.
 
elwood said:
I've left epoxy sitting 6-8 months before. Just sand with 180 , spray couple more coats epoxy and keep on truckin.
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Thanks. So when it comes time to paint i would sand with 180 and shoot unreduced epoxy prior to base? or are you saying 180 then a reduced coat as a sealer and then base? im just trying to figure out the steps to get it from cured epoxy to smooth and ready for base. the 180 seems too coarse but necessary for adhesion. its confusing me lol
 
Reduced epoxy is not going to fill 180 scratches. Sand 180, 2 coats epoxy and then 220, 320, 400. Then apply one coat reduced epoxy sealer in the recoat window and shoot your base.
 
dhutton01 said:
Reduced epoxy is not going to fill 180 scratches. Sand 180, 2 coats epoxy and then 220, 320, 400. Then apply one coat reduced epoxy sealer in the recoat window and shoot your base.
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Yup. What Don said. Or do 3 coats unreduced epoxy instead of 2. You want enough to do your final sanding before doing the reduced coat of epoxy without breaking thru somewhere.
 
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dhutton01 said:
Reduced epoxy is not going to fill 180 scratches. Sand 180, 2 coats epoxy and then 220, 320, 400. Then apply one coat reduced epoxy sealer in the recoat window and shoot your base.
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Ahh that’s it! Makes sense now Thank you.
180 for mechanical adhesion, recoat epoxy to start a fresh round of chemical adhesion, sand to smooth out and hit it with a sealer coat before base (within the recoat window)
 
elwood said:
Yup. What Don said. Or do 3 coats unreduced epoxy instead of 2. You want enough to do your final sanding before doing the reduced coat of epoxy without breaking thru somewhere.
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It makes sense now. Thanks!
Question- so if I do 2-3 coats of reduced and get it sanded up smooth without breaking, is it still necessary for a thinned seal coat before base? Or could base go over that? What’s the purpose of the sealer coat at that stage if the sanded epoxy is still able to provide a chemical adhesion?
 
SEOK said:
It makes sense now. Thanks!
Question- so if I do 2-3 coats of reduced and get it sanded up smooth without breaking, is it still necessary for a thinned seal coat before base? Or could base go over that? What’s the purpose of the sealer coat at that stage if the sanded epoxy is still able to provide a chemical adhesion?
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Only time to reduce epoxy is when spraying one coat as a sealer before base. Unreduced at all other times.
 
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