Abstract: A polyurethane-based reactive mass composed of(a) at least one organic compound in the molecular weight range of from 400 to 12000 containing isocyanate reactive groups and having a functionality from 2 to 8,(b) optionally an organic compound in the molecular weight range of from 62 to 399 containing isocyanate reactive groups and having a functionality from 2 to 8.(c) catalysts,(d) aliphatic isocyanate compounds and(e) optionally other auxiliary agents and additives known per se,characterized in that the aliphatic isocyanate compound used is one based on hexamethylene diisocyanate, hydrogenated diphenylmethane diisocyanate or isophorone diisocyanate containing isocyanurate and/or uretdione units and/or urethane and/or uretoneimine and/or oxadiazatrione groups is suitable for the production of lightfast coatings, including coatings in light colors, in particular for the formation of edgings round wooden panels without these panels having first to be dried down to the maximum dampness of 7% by weight.