Abstract: A method of treating an aqueous suspension of a granular copolymer of vinyl chloride and vinyl acetate which is produced from a copolymerization reaction between the monomers in aqueous suspension in which method, after the end of the copolymerization reaction, the pressure in a vessel containing the aqueous suspension is released by venting and the suspension is then heated in a vessel under conditions of temperature and pressure such that there is a vaporous outflow of water vapor, residual vinyl chloride and residual vinyl acetate from the vessel, wherein there is added to the aqueous suspension, before the start of said heating and preferably before venting but after the end of the copolymerization reaction, an effective amount of at least one steam-volatile phenol such that polymerization of the outflowing vinyl acetate is substantially prevented. The preferred phenol is 2,6-ditertiary-butyl-4-methyl-phenol.