Enamel will dry without the hardener, but it takes up to 30 days for the oxidation process to happen. Hardener speeds up the process to 3-5 days. If enamel with no hardener is subjected to any sort of polishing procedure before the binder oxidizes, the paint rolls up in big chunks instead of smoothing out.
Lacquer paint is simply pigment and solvent, without an oxidizing binder, and can be polished and/or color-sanded as soon as the solvent dries out, usually 12 hours or less. Alkyd enamel, acrylic, and the most recent synthetic paint, urethane, requires at least a few days of drying/oxidizing time before any sort of finishing process is attempted.
Jerry
