Fluid that changes the coat viscosity and drying time to improve its application and help the film flow. Specific thinners should be used for each type of product due to compatibility reasons. Thinners are characterised by solvency (ability to decrease viscosity of the coating), speed of evaporation, resistance and ability to increase the pot life. Each type of coating requires specific thinners (polyurethane coatings require alcohol-free thinners with less than 0.5% water). The choice of a proper thinner, which also depends on the application method, is very important to obtain a perfect result.