Abstract: A polyester resin composition comprising a thixotropic solution of an unsaturated polyester resin in a volatile monomer containing also a polymer which is partially incompatible with the polyester resin solution i.e. forms a hazy solution in it. The partially incompatible polymer can be a polymer of an ester of an unsaturated carboxylic acid.

Abstract: An intumescent composition comprising a polymeric binder, a mineral acid catalyst, a source of carbon, and a blowing agent in which the polymeric binder is a solution of a plasticized unsaturated polyester in an unsaturated monomer.

Abstract: An intumescent composition comprising a resinous binder, an inorganic acid source, a carbon source and a blowing agent, the blowing agent comprises(a) a 2-amino s-triazine of general formula ##STR1## in which R.sup.1 and R.sup.2 are the same of different and are each selected from hydrogen, halogen, hydroxyl and amino groups and alkyl, substituted alkyl, alkenyl and substituted alkenyl groups containing up to 6 carbon atoms and(b) a saturated or unsaturated polybasic carboxylic acid containing no more than 2 non-carboxyl carbon atoms per carboxyl group.