The thin surface layer of the polyorganosiloxane, which is grafted on to the cured fluoroelastomer is derived from a polyorganosiloxane, having reactive functionality of the formula: ##STR4## where R is an alkyl, alkenyl or aryl group having less than 19 carbon atoms or an aryl group substituted with an alkyl or alkenyl group having less than 19 carbon atoms, the functional group A is hydrogen, hy