Last night I was watching "Classic Car Restoration" on DIY network; they were restoring a 1962 T-Bird. Anyway, they were planning to colorsand and polish the original paint. Before they did so they did some tests on a couple of fenders that had been painted more recently.

Kevin Tetz did a demonstration to ascertain whether the paint on the fenders had hardened sufficiently to polish. His simple test was to put some solvent on a clean white cloth and lightly rub it across the surface of the paint. If the rag came up with color on it that indicated that the paint had not hardened, if it came up clean (i.e. the solvent wasn't able to cause the paint to get wet again).

This technique may be useful for determining when our roller jobs using Rustoleum are ready for polishing. I guess we'd use mineral spirits as a solvent.

Anyone else ever heard of this?