epoxy adhesion question

B

bmxpegan411

HI Guys,

a while back a primed a hood in cold conditions with SPI epoxy and let it sit until recently. after a little body work and a few bare metal spots I noticed that the epoxy didn't feather when hit with 80 grit on a DA, but if I use a block and a little finer paper it seems to feather better. My question is should I sand it all off and start again, or should I try to feather those spots and continue? Also, on the bare spots that the epoxy didn't feather I can take my fingernail and scratch it off, which makes me think it's time for a re-do.

side note is I'm painting the front end of a car that I plan on selling before starting on my project, so if it's not 100 percent perfect I won't loose any sleep. Any advice is greatly appreciated!
 
Well two things here.
First, epoxy is not doing right, either from cold at time of spraying or an acid film, is it going to fall off? No as it sounds like you have about 70% adhesion, so it just won't be as strong in guarding against a stone chip.

If your going to sell, feather and move on, however one thing you might do is put car in sun for 2-3 days and see if it finishes curing, if an acid film it will not, if from cold parts, it can.
 
Barry;28135 said:
Well two things here.
First, epoxy is not doing right, either from cold at time of spraying or an acid film, is it going to fall off? No as it sounds like you have about 70% adhesion, so it just won't be as strong in guarding against a stone chip.

If your going to sell, feather and move on, however one thing you might do is put car in sun for 2-3 days and see if it finishes curing, if an acid film it will not, if from cold parts, it can.
Click to expand...


thanks Barry! Sorry for the redundant questions, but will it still cure even if it's been on there for about 3 weeks now? I figure I'll try to feather it best I can and finish it up this weekend, as the weather here in southwest PA is in the mid 70's and sunny.
 
The only way to determine whether the epoxy is going to be OK is put it in the sun for several days, getting the surface hot enough to restart reactions which may have gone dormant from the cold. Once that is done, recheck adhesion. If it still isn't sticking, either the surface was contaminated, or the fresh epoxy got too cold.
 
crashtech;28138 said:
The only way to determine whether the epoxy is going to be OK is put it in the sun for several days, getting the surface hot enough to restart reactions which may have gone dormant from the cold. Once that is done, recheck adhesion. If it still isn't sticking, either the surface was contaminated, or the fresh epoxy got too cold.
Click to expand...

thanks! I'll leave it in the sun to bake all weekend while I fix the fender. Thanks again guys!
 
You should notice more adhesion the evening of the first day in sun, if all is well.
 
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