Another issue. Will clearcoat hardener set up by itself? I have a can of Sherwin Williams UH-70 that I only used 1/4 of. It's been sitting for about a year. When I opened it today to check it, there was a hard surface about 1/8" thick across the top. I had to break it up with a punch. I'm guessing that the rest of it is still good, but I won't have enough to catalyze the remaining 3/4 gallon of clearcoat that I have, and it's a little over $100 per quart.

This has not been my best weekend for painting.