A photocurable composition comprising: a) from 50 to 99.9%, preferably from 70 to 98.9% by weight, based on the total weight of the composition, of at least one ethylenically unsaturated compound; and b) from 0.1 to 35%, preferably from 0.1 to 20%, and more preferably from 0.2 to 15% by weight, based on the total weight of the composition, of at least one compound of formula wherein: R 1 is a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted aryl or a substituted or unsubstituted heteroaryl. Qui is a quinolone group of formula: wherein: R 2, R 3, R 4 and R 5 are, independently of one another, hydrogen, substituted or unsubstituted C1-C20 alkyl, -N(C1-C6 alkyl) 2, piperidino, morpholino, piperazino, -O-Rs, -S-R 8, -O-[CH 2] n -COOR 8 or -S-[CH 2] n -COOR 8 where n=1-8 and R 8 is hydrogen, substituted or unsubstituted C1-C20 alkyl, C1-C50 alkyl which is interrupted by one or more oxygens and which may terminate with a hydroxy group, C1-C20 alkyl, C2-C12 alkenyl, substituted or unsubstituted aryl, heteroaryl or C5-C6 cycloalkyl; R 6 is hydrogen, a hydroxy group or a C1-C4 alkyl group; R 7 is hydrogen or a C1-C10 alkyl group; or Qui is a substituted or unsubstituted benzo-quinolone group of formula: wherein R 7 is hydrogen or a C1-C10 alkyl group and the star indicates the carbon atom which is bound to the keto group of formula. a) from 50 to 99.9%, preferably from 70 to 98.9% by weight, based on the total weight of the composition, of at least one ethylenically unsaturated compound; and b) from 0.1 to 35%, preferably from 0.1 to 20%, and more preferably from 0.2 to 15% by weight, based on the total weight of the composition, of at least one compound of formula wherein: R 1 is a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted aryl or a substituted or unsubstituted heteroaryl. Qui is a quinolone group of formula: wherein: R 2, R 3, R 4 and R 5 are, independently of one another, hydrogen, substituted or unsubstituted C1-C20 alkyl, -N(C1-C6 alkyl) 2, piperidino, morpholino, piperazino, -O-Rs, -S-R 8, -O-[CH 2] n -COOR 8 or -S-[CH 2] n -COOR 8 where n=1-8 and R 8 is hydrogen, substituted or unsubstituted C1-C20 alkyl, C1-C50 alkyl which is interrupted by one or more oxygens and which may terminate with a hydroxy group, C1-C20 alkyl, C2-C12 alkenyl, substituted or unsubstituted aryl, heteroaryl or C5-C6 cycloalkyl; R 6 is hydrogen, a hydroxy group or a C1-C4 alkyl group; R 7 is hydrogen or a C1-C10 alkyl group; or Qui is a substituted or unsubstituted benzo-quinolone group of formula: wherein R 7 is hydrogen or a C1-C10 alkyl group and the star indicates the carbon atom which is bound to the keto group of formula. R 1 is a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted aryl or a substituted or unsubstituted heteroaryl. Qui is a quinolone group of formula: wherein: R 2, R 3, R 4 and R 5 are, independently of one another, hydrogen, substituted or unsubstituted C1-C20 alkyl, -N(C1-C6 alkyl) 2, piperidino, morpholino, piperazino, -O-Rs, -S-R 8, -O-[CH 2] n -COOR 8 or -S-[CH 2] n -COOR 8 where n=1-8 and R 8 is hydrogen, substituted or unsubstituted C1-C20 alkyl, C1-C50 alkyl which is interrupted by one or more oxygens and which may terminate with a hydroxy group, C1-C20 alkyl, C2-C12 alkenyl, substituted or unsubstituted aryl, heteroaryl or C5-C6 cycloalkyl; R 6 is hydrogen, a hydroxy group or a C1-C4 alkyl group; R 7 is hydrogen or a C1-C10 alkyl group; or Qui is a substituted or unsubstituted benzo-quinolone group of formula: wherein R 7 is hydrogen or a C1-C10 alkyl group and the star indicates the carbon atom which is bound to the keto group of formula. R 2, R 3, R 4 and R 5 are, independently of one another, hydrogen, substituted or unsubstituted C1-C20 alkyl, -N(C1-C6 alkyl) 2, piperidino, morpholino, piperazino, -O-Rs, -S-R 8, -O-[CH 2] n -COOR 8 or -S-[CH 2] n -COOR 8 where n=1-8 and R 8 is hydrogen, substituted or unsubstituted C1-C20 alkyl, C1-C50 alkyl which is interrupted by one or more oxygens and which may terminate with a hydroxy group, C1-C20 alkyl, C2-C12 alkenyl, substituted or unsubstituted aryl, heteroaryl or C5-C6 cycloalkyl; R 6 is hydrogen, a hydroxy group or a C1-C4 alkyl group; R 7 is hydrogen or a C1-C10 alkyl group; or Qui is a substituted or unsubstituted benzo-quinolone group of formula: wherein R 7 is hydrogen or a C1-C10 alkyl group and the star indicates the carbon atom which is bound to the keto group of formula.