This paper gives the results of a number of dental casting experiments, showing effects of physical properties of the materials used in the casting process upon the finished casting. The dimensions of the castings are shown to be changed by the type of investment, casting temperature, water-powder ratio of the investment, and the treatment of the wax pattern. Castings are shown that correlate physical data and actual results. Castings made in cristobalite (75 cristobalite, 25 plaster) investment, and cast at various temperatures from 400°C. to 800°C., all gave accurate restoration.