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.
How to speed up the process of drying the oil quite a lot. One of them is the adding impurities of zinc, manganese, lead, cobalt, which are added in the form of salts of organic acids. These salts are called sequests and they greatly affect the process of drying the oil in terms of speed and also some of the main and additional properties of the resulting coating. With the introduction of a sequcase in oxidized or polymerized oils, it turns out olifa. Sometimes excess salts of heavy metals delay the process of drying varnishes or simply spoils the quality of the applied oil. Sickatives also affect the process of aging of the coating in the same way and therefore this element should be used only in certain and very accurate proportions. When heating oils to 250 degrees Celsius, partially organic radicals simply break off, oxygen appears instead of them. This allows us to understand what, when heated, it is necessary to use special hardeners, which do not allow the process to go under control at 200-250 degrees drying of the varnish.
