Strain gage (gauge) installation on glass

Glass surfaces are extremely smooth and practically impervious, because of which adhesives do not get a good hold, and bonding strain gages to glass becomes a challenge. For most tests on glass, abrasion of the surface is not permitted as it would produce score marks that could initiate fracture due to the brittleness of glass. In this exercise, in an attempt to get a satisfactory bonding of a strain gage, slight abrasion of the surface was done with a 600 grit abrasive paper. This did not produce any visible score marks on the glass, and barely removed any material from the surface. But under good lighting, the abraded surface appeared slightly dull, which helped in the bonding of the Micro Measurements strain gage. The strain gage was connected to a Micro Measurements Model P3 strain indicator and the glass beam was tested under load. Because of the brittleness of glass, and its ability to shatter unpredictably, loading of the glass beam was restricted to small weights.