One component in-mold coating

The method which comprises in-mold coating a molded thermoset polyester resin or thermoset vinyl ester resin glass fiber composition containing from about 10 to 75% by weight of glass fibers with a one component thermosetting in-mold coating composition under pressure, at a temperature and for a period of time sufficient to cure said in-mold coating composition to form an adherent thermoset coating on said molded thermoset resin glass fiber composition, said in-mold coating composition comprising

• (a) a liquid crosslinkable composition having an average molecular weight of up to about 5,000, having a plurality of polymerizable ethylenic double bonds, being essentially free of active hydrogen atoms or being essentially free of isocyanate groups,
• (b) a material selected from the group consisting of (I) a polyisocyanate and (II) the reaction product of an excess of equivalents of a polyisocyanate and an ethylenically unsaturated compound having --NH.sub.2, --NH-- and/or --OH groups, said reaction product being free of active hydrogen atoms and
• (c) an organic free radical peroxide initiator in an amount sufficient to effect curing of said in-mold coating composition, said (b) being used in an amount sufficient to secure the adhesion of said coating composition to said molded thermoset resin glass fiber composition.