Alkyd enamel needs a MINIMUM of 30 days' curing time before any attempt is made to sand or even polish it. The solvent evaporates out pretty quickly, but the carrier of the pigment ("binder") needs time to oxidize and harden. When quick-curing acrylic enamels and isocyanate hardeners came on the market about 40-something years ago, people started to forget how much hassle alkyd was to deal with. About the only place I see alkyd enamel for sale any more is "tractor and implement" paint, sold by farm equipment places like Co-Op, or Tractor Supply Co., etc.
The cyanide-based chemicals in isocyanate hardeners are contact poisons, meaning they can be absorbed through the skin. To use them safely, it's necessary to wear a full-coverage "shoot suit", preferably one with a separate air supply drawn through a good chemical filter. Some of my painter friends who used isocyanates on a regular basis have developed some pretty nasty chronic health problems from the toxicity of the products.
Jerry
