BimmerFest BMW Forum banner

Sticky Clear Coat

9101 14
So I repainted part of the nose panel this weekend and the clear coat has dried sticky. Humidity was low (around 20%), was left in a closed garage and hasn't bubbled or anything. It's just sticky. I'm gonna have to goof it and start over but does anyone have some solid advice on how to prevent this or anything I can do after it dries to remove the stickyness? I was thinking something along the lines of a rubbing compound. Thanks.
1 - 15 of 15 Posts
A finish coat that stays sticky didn't cure properly. It may never fully harden, either. Are you sure the clear was compatible with the base coat?
What brand and part number base coat did you use? What brand and part number clear did you use? Was it a one part or two part type?
If you sprayed acrylic lacquer clear over enamel it will never harden and in fact you'll need to strip both the clear and the base coat.
Paint brand is Automotive Touch Up (automotivetouchup.com), code 668 Jet Black BMW paint. I got the matching clear coat, and the only one they have and designed for their paint. I'll check the bottles when I get home and give some ingredient information.
Did you add the hardener to the clear?
Everything is 1k, no hardeners.

Acrylic Urethane basecoat, not Enamel.
I checked the ATU website and the only 1K clear they offer is acrylic lacquer. I suspect that's your problem. It's a known fact that you can't spray lacquer over enamel because the very aggressive solvent in the lacquer penetrates the enamel and softens it. Google search doesn't turn up anyone who says it's OK for lacquer over urethane and it's likely for the same reason you can't spray it over enamel.
I've searched around too, nothing definitive on Acrylic Lacquer clear being used on Acrylic Urethane. However ATU only sells Urethane base paint, meaning they would be selling a clear coat that would never cure properly. They do sell a 2K Urethane clear which I could go for but I'm going to see what they say first, I'm betting more on an application issue rather then a chemical issue.
If you're using rattle cans there's not too much you can do from an application standpoint.
Well the only thing left to do is give it more time to dry and cure and see if it feels any different by the weekend. In the meantime I'll see what the paint manufacturer says. If it gets to a more smooth feel by the weekend, I'll buff it with 1500 grit wet and see where that takes me.
I was at a body shop today and asked about the lacquer clear over the urethane base. They said they thought that was the problem with your sticky finish.
Paint manufacturer got back to me, apparently it can have a tacky feel if the coat was applied too heavily and if it's not left to dry long enough between coats. It eventually dries out and gets smooth and non-tacky. I can safetly say it feels much nicer now and should feel natural once I wet sand it with 1200 grit and buff it with rubbing compound.
DO NOT wet sand it until it's completely non-sticky feeling, hard and dry. You'll just make a huge-er mess if it's still tacky..
x2

You have to use the exact same type of paint. All the way from primer, base coat, up to clear. Or they'll never fully cure.

With all three being compatible, paint should dry to a touch within 24 hours, and fully cure within 30 days.
A finish coat that stays sticky didn't cure properly. It may never fully harden, either. Are you sure the clear was compatible with the base coat?
Yeah everything is dry and smooth now. I applied the clear too heavy and didn't let the coats dry long enough between sprays. So even after 24 hrs it was tacky feeling. Having been days later now, everything looks and feels good. Except for the part my garage door landed on the other day.... oops. Good thing it's just the nose panel. Thanks for the insight on this guys!
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top