Epoxy on ABS not holding

F

FStanley

So I have an ABS trim part

I cleaned it very well with soap and water, then 700-1 cleaner

sanded with 80 grit then blew off with filtered air, then 700-1 cleaner and waited over night to dry.

Temps 70-82F thoughout day

shot one coat of adhesion promoter 600-4 , waited 40 minutes

Shot 1 good wet coat of SPI epoxy primer reduced 10% with acetone.

waited overnight total 20hrs

wanted to level out a bit of the epoxy before adding another coat of unreduced epoxy

Sanded with 220 grit

not feathering out.. tearing... came right off..


did same thing to a previous ABS part and worked great, sanded great, feathered great..

did two things differently sanded with 180 grit not 80, waited one day then overnight, next day put in 93F degree sun for one day.. next day sanded great. feathered great, etc...

was the epoxy not cured enough???

other thoughts???

any feedback greatly appreciated

Fred
 
No need for 80# on plastic. No need for adpro on ABS. No need to reduce epoxy(only SPI reducer) until used for a sealer before base. Overnight the epoxy does not have full adhesion and tends to rip off the substrate if sanded through, especially with a coarse sandpaper. As crash said, just sand it with 320 or 400 wet, clean and apply more epoxy.
 
if it really is abs then there is no need to even sand it. your wasting your time. a quick test would be to squirt some acetone on a rag and wipe the plastic part on an unseen area. if the acetone and rag bite into the plastic then it is abs and no need to do anything. just shoot a super thin coat of epoxy as a sealer, let flash then proceed to paint it. all our paints are solvent base and will melt and bite right into abs and lock on. if you bother to sand it then the paint just melts the sanded plastic back into a smooth surface again so it really is pointless and just causing you extra work. the epoxy probably is not stuck because the abs is still soft with solvent. it would eventually come out and harden up. so no adpro, no sanding or scuffing of any kind. just clean it and paint it.
 
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