A composition, the average isocyanate functionality of which is greater than 2.5 and for which the NCO titre is between 10 and 25% by weight, comprising - at least one polyisocyanate compound with biuret units (a); - at least one polar, protic reactive diluent compound (b), chosen from polyisocyanate compositions with allophanate units, the viscosity of which measured at 25°C is less than 500 mPa.s; - at least one addition compound (c), a compound (a) and a compound (b) and - at least one aprotic reactive diluent compound (d) chosen from a compound of formula, a compound of formula, a compound of formula and a compound of formula wherein a. R 6 and R 7, identical or different, independently represent a linear, cyclic or branched C 2 -C 20 alkyl group, comprising at least one isocyanate function; preferably a linear, cyclic or branched C 2 -C 12 alkyl group, comprising at least one isocyanate function; more preferably a linear or branched C 2 -C 12 alkyl group, comprising at least one isocyanate function; in particular a linear or branched C 4 -C 12 alkyl group, comprising at least one isocyanate function; b. R 8,R 9,R 11,R 12,R 13 R 14 and R 15, identical or different, independently represent a linear, cyclic or branched C 2 -C 20 alkyl group; preferably a linear, cyclic or branched C 2 -C 12 alkyl group; more preferably a linear or branched C 2 -C 12 alkyl group; in particular a linear or branched C 4 -C 12 alkyl group; a linear, cyclic or branched C 2 -C 20 alkyl group, comprising at least one isocyanate function; preferably a linear, cyclic or branched C 2 -C 12 alkyl group, comprising at least one isocyanate function; more preferably a linear or branched C 2 -C 12 alkyl group, comprising at least one isocyanate function; in particular a linear or branched C 4 -C 12 alkyl group, comprising at least one isocyanate function. - at least one polyisocyanate compound with biuret units (a); - at least one polar, protic reactive diluent compound (b), chosen from polyisocyanate compositions with allophanate units, the viscosity of which measured at 25°C is less than 500 mPa.s; - at least one addition compound (c), a compound (a) and a compound (b) and - at least one aprotic reactive diluent compound (d) chosen from a compound of formula, a compound of formula, a compound of formula and a compound of formula a. R 6 and R 7, identical or different, independently represent a linear, cyclic or branched C 2 -C 20 alkyl group, comprising at least one isocyanate function; preferably a linear, cyclic or branched C 2 -C 12 alkyl group, comprising at least one isocyanate function; more preferably a linear or branched C 2 -C 12 alkyl group, comprising at least one isocyanate function; in particular a linear or branched C 4 -C 12 alkyl group, comprising at least one isocyanate function; b. R 8,R 9,R 11,R 12,R 13 R 14 and R 15, identical or different, independently represent a linear, cyclic or branched C 2 -C 20 alkyl group; preferably a linear, cyclic or branched C 2 -C 12 alkyl group; more preferably a linear or branched C 2 -C 12 alkyl group; in particular a linear or branched C 4 -C 12 alkyl group; a linear, cyclic or branched C 2 -C 20 alkyl group, comprising at least one isocyanate function; preferably a linear, cyclic or branched C 2 -C 12 alkyl group, comprising at least one isocyanate function; more preferably a linear or branched C 2 -C 12 alkyl group, comprising at least one isocyanate function; in particular a linear or branched C 4 -C 12 alkyl group, comprising at least one isocyanate function.