Abstract: in accordance with the invention, a method of continuously treating an aqueous latex of a synthetic polymer contaminated with unreacted residual monomer used in the production of the polymer, comprises feeding the aqueous latex as a spray into a vessel defining a chamber so that all or a substantial quantity of the droplets of spray avoid contact with the side wall of the chamber, and contacting the falling spray with steam flowing counter-current thereto, whereby residual monomer is separated from the latex and is removed with the flow of steam leaving the chamber. Preferably at least 80% by weight of the droplets of spray avoid contact with the side wall of the chamber. Apparatus which includes the vessel and means to provide a flow of steam up the chamber to contact the falling spray is also disclosed.In this method all or most of the spray falls directly to the bottom of the chamber without touching the side wall of the chamber. In this way foaming difficulties are avoided.