Surface Defects

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

Guest User
Tue, 27/07/2004 - 22:58


With 170 views and no response, I think you better ask a few window cleaners. Most QUALITY temperers do not have this problem, but there are a few other poor quality temperers out there that don't seem to be cleaning their glass properly, prior to the heat
cycle, which causes this problem.

Any glass dust or chips still on the glass as it enters the tempering furnace WILL cause a blemished surface, which WILL cause scratching during standard window cleaning.

I have supplied builders, window cleaners, window manufactures and any one else interested in understanding the fact with more information on this issue along with other ways to prevent scratched glass.

The IWCA (International Window Cleaning Association) has just published a bulletin warning their members on this issue and suggest they gat a waiver before cleaning ANY tempered glass.

Good Luck,

Dan Fields
Fields CSI

Guest User
Mon, 03/01/2005 - 13:14

I am NOT a glass manufacturer but I have had a great deal of experience with defective glass during the post construction clean down - related to surface defects or "fabrication debri"

What Dan Fields has submitted is SO TRUE, please take EXTREME CARE and TEST all glass surfaces prior to cleaning.

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