Using 2.5-25μm infrared rays, tests by Infrared Absorption Spectrum have been made on different lacqure coatings of surfaces of furniture, boards of sewingmach-ines, etc. coated with polyurethane clear lacquer. According to the theory of molecular structure and the absorbent property of different lacquer coatings the best infrared wave-length of dried coatings has been obtained. This will provide a reliable basis for the choosing of infrared radiation source in production.