Winter is fast approaching, and it may be that your shop or garage is not warm enough for finishes to dry in a reasonable time. With varnish (including polyurethane varnish), shellac or water-based finish, the only thing I know to do is bring the project into your house or other warmed structure. (If the object is small, you could put it in front of a heater or use a hair dryer.) If you’re spraying lacquer, there’s an easier solution that avoids creating the unpleasant odor in your house.
You can try thinning your lacquer with acetone instead of lacquer thinner. Acetone evaporates quite rapidly and may be enough to make your lacquer dry
in the cooler temperatures.
Even better, if you can buy it where you live, switch to 275 VOC lacquer. That is, lacquer that is compliant with the strictest VOC laws. These laws allow manufacturers to use up to 27.5 percent non-compliant solvents in making their finishes. Lacquer, however, needs well over 27.5 percent solvent to make it thin enough to spray. So manufacturers typically use acetone, which is an exempt solvent, to thin the lacquer enough to spray. This results in the lacquer drying considerably faster, so it works well in a cold shop.
The problem with 275 VOC lacquer, of course, is that it often dries too fast in the summer, if you can’t get your shop cool enough or move fast enough.
Further Reading: Insulating and Preparing the Shop for Winter