A foam control composition comprises a polydiorganosiloxane fluid comprising units of the formula where each group R, which may be the same or different, is selected from an alkyl group having 1 to 36 carbon atoms or an aryl group or aralkyl group having up to 36 carbon atoms, the mean number of carbon atoms in the groups R being at least 1.3, and an additive composition of melting point 35 to 100° C. comprising a substantially non-polar organic material, preferably a polyol substantially fully esterified by carboxylate groups each having 7 to 36 carbon atoms.