A New Model Material for Photo Elasticity

GELATIN, and a number of imported plastics like 'Catalin 800', 'BT.61-893', 'CR-39', 'Marco Resin', etc., are commonly used as model materials. Gelatin is optically more sensitive than all other materials, but has some disadvantages. The stress-optical sensitivity of gelatin1 varies considerably with the gelatin concentration, glycerine content and temperature; the recommended working range of temperature is $14^o–19^o C$.2 In the tropics, the gelatin mix is very weak elastically at room temperature, whereas gar has proved to be more stable