In a silicone impression and duplicating composition which undergoes crosslinking at ambient temp. by an addition reaction, comprising (a) an organopplysiloxane possessing two or more vinyl groups in the molecule, (b) optionally an organopolysiloxane without reactive groups, (c) an organopolysiloxane possessing two or more Si-H groups in the molecule, (d) a catlayst, (e) a filler and, (f) optionally an auxiliary and/or colorant, the improvement wherein polysiloxane components (a)-(c) contain not more than about 1.5% by wt. of volatile oligomers, whereby the dimensional stability of impressions is improved. |