Film -forming substances that are used to obtain paintwork are most likely to start with the most long -known, and therefore widely used substances. It has long been noticed by people that when applying thin layers of some vegetable oils, after it dries on the surface, a strong and elastic coating remains. Different oils in time dry in different times starting from 8 days to 40 days (castor).All these oils are essentially composed of various types of family of substances called fatty acids and they contain a special kind of double bonds. These connections, when exposed to oxygen on them, as well as especially when exposed to elevated temperatures on them and oxidize in the sun, or more precisely, oxidative polymerization of oils occurs at the same time, the oil itself dries and turns into a high molecular weight — linoxin. Since there are a different amount of acids in the composition of the oils, the duration of the drying of the oils is also different.