It's the tack cloth.

Posted by CLC on Feb 27, 2005

The chemicals in a tack cloth (wax, and some other crap) couldn't be more ideally suited to act as a release agent for the epoxy. "Fisheye" city.

Denatured alcohol is a good solvent but probably not powerful enough to dissolve away the wicked waxy stuff left behind by the tack cloth.

Here's what to do:

Buy some lacquer thinner. It's nasty stuff; acrid and dangerous but pure as the driven snow. Check your ventilation. Then get a really clean rag---and this is important, because rags can have fabric softener and other nasties in it---and wipe everything down.

Make sure there isn't something else nearby that's causing the surface contamination, like a clothes dryer that's spewing particles of fabric softener, for example.

Then...roll on a last coat of epoxy. This should fill in the little orange peel pits. I'm 99% sure it will work, because I've been where you are so many times.

At last, you should be able to sand it flat and move on to paint and varnish.

The moral is, never use tack rags between coats of epoxy. Tack rags are okay with non-urethane paints and varnishes, but otherwise they're the very devil.

In Response to: Discouraged MC13 builder by Lou on Feb 27, 2005