Things about ASTM-C1279-00: Standard test method for non-destructive photoelastic measurement of edge and surface in annealed, heat-strengthened, and fully tempered flat glass
1.1 This test method covers the determination of edge stresses and surface stresses in annealed, heat-strengthened, and fully tempered flat glass products.
1.2 This test method is non-destructive.
1.3 This test method uses transmitted light and is, therefore, applicable to light-transmitting glasses.
1.4 The test method is not applicable to chemically- tempered glass.
1.5 Using the procedure described, surface stresses can be measured only on the “tin” side of float glass.
1.6 Surface-stress measuring instruments are designed for a specific range of surface index of refraction.