Abstract: The invention relates to a multi-layer coating system comprising: at least one layer a) comprising a coating composition a) comprising at least one isocyanate-functional compound and at least one thiol-functional compound; and at least one layer b) comprising a non-aqueous coating composition b), wherein at least one layer a) and at least one layer b) have at least one common layer boundary, and wherein coating composition b) comprises all effective amount of a catalyst for the addition reaction of tile at least one thiol-functional compound and the at least one isocyanate-functional compound.

Abstract: The invention relates to a spray gun for application of a coating having a spray nozzle and at least one actinic radiation outlet, characterized in that the at least one actinic radiation outlet is positioned externally and the radiation outlet and the spray nozzle are simultaneously directable to a substrate to be coated, and to a process of applying a coating composition which is at least partly curable by actinic radiation. The spray gun according to the invention is suitable for all types of actinic radiation-curable coating compositions, even if there is no induction period between the initiation by actinic radiation and the actual onset of the curing reaction. The balance of flow of the coating material just after application and the drying speed are particularly favourable.