The use of a composition which is liquid under standard conditions (20° C., 1 bar) as a coating material, wherein the composition comprises a) an unsaturated polyester resin composed of α-olefinically unsaturated polycarboxylic acids, polyols, and optionally further compounds, b) compounds with vinyl ether groups (vinyl ethers for short), and c) optionally α-olefinically unsaturated polycarboxylic acids or their monoesters or diesters, where the sum of the double bonds of the α-olefinically unsaturated polycarboxylic acids from a) and optionally of the compounds c) to the double bonds of the vinyl ethers b) is in a molar ratio of 1.3:1 to 0.8:1.