Fab Debris & Scratched Glass

Fabrication debris on tempered and heat strengthened glass has become a major problem. Unfortunately general contractors, window manufacturers, and building owners know very little to absolutely nothing about it. Yet this type of defective glass can be the result of the loss of millions of dollars in wasted windows. Anyone can inadvertantly come across this type of glass and do damage. The big debate going on now is whether to use or not use razor blades in cleaning tempered glass. Simply put razor blades are NOT the cause of this problem. It is the fabrication debris left on the surface of the glass during the tempering or heat strengthening process. Any extremely small pieces of glass which have contaminated the rollers of the tempering oven can be picked up by the glass sheets. These particles come from the glass when it is scored and cut to size. They might not have been completely cleaned from the glass before tempering. Also they might have contaminated the rollers in the oven which have not been maintained clean and in good condition. Either way they wind up permanently embedded in the surface of the glass as it passes through the oven. When the glass is cleaned there is always a risk that they might be dislodged in some way and dragged across the window. When this happens scratches result. They can be dislodged by plastic as well as metal razors. They can be dislodged by plastic wool, steel wool, or even felt pads. Thats right! I talked with a window cleaner the other day who specializes in glass restoration. He removes stains, and scratches from architectural glass surfaces. The commercial machine he uses is very advanced. But he told me that he recently turned down a job where the glass had been scratched by microfines/fabrication debris. Why? Simply that any loose particles left on the glass could easily get in between the polishing pad and the glass surface causing millions of additional scratches.
Fabrication debris is a problem that needs to be dealt with. It first must be recognized. That is why I am writing this blog. But since this type of defective glass is already out there it needs to be understood that only professional window cleaners who have an intimate knowledge of this problem should be hired to clean windows. They need to know where tempered glass is, and how to quickly learn if they are working on a defective surface. Many professional window cleaners have even seen fit to have a waiver signed. Because no one has decided to put a label on this glass marking it clearly as defective, we are all left to own own devices in dealing with it. We do our best but everyone has limitations. And we are not the ones who are responsible for this problem. We are actually doing everything in our power to educate as many others about it so as to prevent scratches on glass. We are working hard to stop scratched glass!

Henry Grover Jr.
Glass Tech Consulting
gtcnews@hotmail.com