A stucy of duplication variables related to partial denture castings

A series of stone duplications of a standard impression die was produced, using a proprietary duplicating material, the various batches of which had been prepared differently. Two different sized duplicating vessels were also employed. The critical dimensions of the stone reproductions were compared with those of the original die. Specimens of each batch of duplicating material were tested to determine the degree of permanent deformation produced by a fixed strain and strain in compression.