GLASS TESTING refers to the measurement of surface stresses in glass to determine whether it meets the criteria for heat strengthened (HS) or fully tempered (FT). The test is conducted using the GASP (Grazi ng Angle Surface Polarimeter). This is an important measurement as it involves safety glass, to make sure the glass has the right properties for the application. Tests for light and energy transmittance and reflection are conducted in cooperation with an associate lab.