The durability of a paint system depends on many external factors such as the environment, the design of the structure, the surface preparation, and the application and drying procedures. For this reason, the resistance of the finishing coatings to the environment is a crucial feature. It determines its durability. The finish coating or topcoat must be inert to the environment in which it is operated and to maintain its physical and mechanical properties for a long time. Depending on the type of the operating environment the main factors to be taken into consideration are weatherproofing, water resistance, heat resistance, acid resistance, alkali resistance, oil resistance, gas resistance, light resistance, cold resistance, resistance to biological factors (molds, fungus and etc.).