Epoxy anticipated issue

MKH

Promoted Users
I have done the following: car ( just the body) sanded to bare metal, SPI epoxied, body worked and 2 coats of 2k primer. I am now working on the fenders, hood, doors and other small parts. The body will be sitting for a few months before I can get back to it to start block sanding the 2k primer. I feel like I will probably have some areas that I will break thru the 2k and expose the epoxy. ( mostly edges). How do you guys handle this? The epoxy will be out of the re-coat window. Thanks
Mike
 
I would finish the body, guide coat, block sand, repeat until you're happy, then shoot another coat of epoxy as a sealer.
Get your other panels done, then when ready to paint, simply wet sand the epoxy, clean it up and you should be ready to shoot color.
 
So it can sit in a reduced coat of epoxy for an extended time? I’ll be spraying metallic so my plan was to sand the 2k to 600 grit and then spray a sealer coat of epoxy just before base coat. Are you saying I can spray a sealer coat of epoxy on the body now then wet sand the reduced coat of epoxy with 600 grit before I apply the base even though it will be past 60 days? Thank you.
Mike
 
So it can sit in a reduced coat of epoxy for an extended time? I’ll be spraying metallic so my plan was to sand the 2k to 600 grit and then spray a sealer coat of epoxy just before base coat. Are you saying I can spray a sealer coat of epoxy on the body now then wet sand the reduced coat of epoxy with 600 grit before I apply the base even though it will be past 60 days? Thank you.
Mike
Yes, I have had stuff sitting in epoxy for well over two years.
Like Texas said, the Epoxy will protect it, while sitting in 2k is asking for problems with contamination.

When you get ready to paint, sanding with 600 will be fine, but after sanding you could also put another coat of reduced epoxy as a sealer if you choose. Always follow the Tech Manual for all your products as pertaining to flash and topcoat times.
 
Okay. I was confused reading that epoxy had to be sanded with 180 grit before applying anything else if it’s been longer than 30 days. Since the 2k will be blocked to 600 I didn’t want to revert back to the 180. I will spray a sealer coat of epoxy and let it sit until I’m ready to paint. Then just block it with 600 and spray a sealer coat of epoxy just before base. So epoxy will stick to sanded 600 grit epoxy outside the window? Thanks for the help.
 
Think of it this way. There is mechanical and chemical adhesion. Chemical is always stronger. After a certain period of cure time, chemical adhesion is lost. Epoxy takes much longer to lose chemical adhesion than 2K. Therefore, after something is fully cured, you are relying on mechanical adhesion only. Coarse, deeper scratches give better mechanical adhesion than fine, shallow scratches because there is more surface area for the product to grab on to. What this all boils down to is compromises. How much adhesion is needed to keep the paint from peeling, or chipping easily? The absolute best would be chemical adhesion start to finish, but that is not always practical. Second best would be mechanical with coarse scratches, again not always practical. You can't spray base over 180 scratches, for example, because of appearance, but the adhesion would be better than 600 scratches. My point in all of this is to shoot for as much chemical adhesion as practical, and use the coarsest sandpaper possible, that won't cause appearance issues.
 
Last edited:
Back
Top