Alkyd-based polyurethane coatings (PU) are chemically curing solvent-based coatings, in which two raw material groups (hardeners and binders) react with one another. PU alkyd coatings are characterised by a high solid content and great durability. However, due to the raw materials, fastness to light is not as good as, for example, in the case of PU acrylic coatings. Nevertheless, here we only use the best raw materials and thus manage to keep yellowing to a minimum.