Tempered glass can collect microfines from dirty rollers when it passes through the lehr. When cool these become permanently embedded in the surface. If you drag a penny across a dry surface it sounds like sandpaper. When removing anything with even a plastic scraper the microfines are dislodged and dragged, resulting in billions of very fine scratches. These defective surfaces can be very problematic. I was wondering if any window manufacturers have had any experience with them?
Henry Grover Jr.
Glass Tech Services