The present invention provides a tin-free, room temperature curable silicone elastomer composition, wherein the uncured composition is a putty. The silicone elastomer composition comprises a) an end-capped base polymer, wherein the base polymer comprises a polysiloxane or mixture of polysiloxanes, and wherein the end-capped base polymer comprises terminal di-(C1-4)alkoxy silyl groups; b) at least one amorphous filler; c) 15.1 to 60 parts by weight of at least one spherical filler for each 100 parts by weight of base polymer; and d) a curing catalyst consisting of one or more selected from the group consisting of organic titanates and organic zirconates. The terminal dialkoxy silyl groups of the base polymer can be dimethoxy silyl groups. The at least one amorphous filler can be selected from the group consisting of fumed silica, fumed alumina, carbon black, precipitated silica, precipitated calcium carbonate, surface-treated calcium carbonate and mixtures thereof.