Described herein is curable composition comprising a halogenated amorphous polymer having at least 25% halogen by weight; at least 0.5 phr of an acid acceptor; at least 0.01 phr of silicon-containing compound; and a dehydrohalogenation cure system. Upon curing, a silicon-containing superficial layer forms, which can provide increased durability, non-tackiness, and a matte finish to the cured elastomer.