THE PROCESS OF DRYING INVOLVES SEVERAL physical and/or chemical changes, such as solvent evaporation, oxidation, and polymerization, all of which are time dependent. The various stages of drying that occur in organic films may be subjective, difficult to measure reproducibly, and are influenced by many factors such as film thickness, substrate, temperature, humidity, light, and air circulation. Therefore, it is essential that most of these variables must be minimized in order to make drying time determinations more quantitative.