Preparation of heat curable organopolysiloxanes

A method is provided for making a one part heat curable platinum group metal catalyzed organopolysiloxane composition exhibiting improved shelf stability which employs as the platinum group metal catalyst an inclusion compound of a cyclodextrin and a platinum group metal material which is made by initially recovering the catalyst in crude form as an inclusion compound of a cyclodextrin and a platinum group metal material from an aqueous mixture, drying the crude complex and thereafter washing the resulting dried product with an organic solvent until the resulting inclusion compound is substantially free of uncombined guest molecules.