Posted by Dave on Wednesday, March 10, 2004 at 12:04PM :
In Reply to: windshield woes posted by Don in Missouri on Wednesday, March 10, 2004 at 9:38AM :
I deal with glass regularly for building. Auto glass is required to be tempered and laminated. The laminate is a clear PVB. Tempering is a process where the glass is superheated, then slapped into room temperature thereby forming 3 tension layers. If you can imagine taking a frozen turkey, and slamming it in the oven at 450 degrees, the outside would burn, and the inside remains frozen. Its the same for glass but only in reverse. And yes, tempered glass does suffer from "spontaneous breakage" caused by nickel sulfide occlusions. Probably not the cause of your problems.
Your frame is stressing the glass. Secondly, you may have metal to glass contact. Be sure to get your glass with "ground" edges. Second, take fishingline and check for frame straigtness. Third, install the proper method and be sure no bump exists that the glass sits on. Remember, glass cannot be warped without eventually breaking from thermal loading.