When it is over 100 deg. F, it is best to stop and do something else. Film looks whitish, cloudy, or milky. Use air assist hot spray airless for clear lacquers in summer and winter. To much air pressure to pump and air assist can cause tiny bubbles or gassing along the grain.
Film looks bluish, or iridescent.
Extend Dry Times of oil based products in cold or humid conditions. Runs and drips of lacquer that collect by gravity in thick ridges. First coat flakes off with fingernail and edges or corners chip off easily with minor impact, or bumps. Dusty surface or other surface contamination, poorly cleaned or prepared just prior to spraying. Too much atomization air or too little material leaving the gun.