Clear coating composition

A composition comprising: (a) a polyene with isocyanate functionality; (B) a polythiol. in which (a) has the structural formula A- (X) m where A is derived from a polyisocyanate (cyclo) aliphatic diisocyanate selected from 1,6-hexamethylene diisocyanate, isophorone diisocyanate isocyanurate and its derivatives including biuret; X is an olefinically unsaturated moiety and m is at least 2.