Chemistry of Polysulfide Impression Material

The base plate, is a polysulfide polymer that contain a multi-functional mercaptan (-SH) called a polysulfide polymer, a suitable filler such as lithopone or titanium dioxide to provide the required strength a plasticizer (dibutyl phthalate) to confer appropriate viscosity to the paste and a small quantity of sulphur, approximately 0.5 % as an accelerator the catalyst paste contains lead dioxide, filler and plasticizer as in the base paste, and oleic stearic acid as a retarder to the control the rate of the setting reaction.