What the heck is fabrication debris? In recent years, low-quality heat-treated (i.e., tempered) glass has become a major source of scratched glass. Poor quality control during fabrication leaves microscopic pieces of “debris” on the surface of the glass. When the razor hits this debris during cleaning, the glass scratches...not good.
micro-chips of silicate on glass
scratches resulting from razoring defective glass
(note: window not cleaned by LRWC)
What should I know about tempered glass?
Tempered glass is similar to regular (i.e., annealed) glass is every way except that it’s 4-5 times stronger and breaks into small pieces thus making it safer to withstand impact and safer when broken.
Quality tempered glass surfaces are the same as annealed glass surfaces.
Both sides of the glass are tempered but only one side will contain fabrication debris.
Every piece of tempered glass should contain a stamp identifying it as such.
Where is tempered glass typically used? Use depends on local residential building codes but most often found in:
new construction or glass installed since about 2007
doors (sliding, french)
sidelights and transoms surrounding doors
all windows within 18-in of the floor
lower bathroom windows
How to identify if glass has potential for fabrication debris? If the window has been razored in the past and fabrication debris is present, the window will show widespread scratches. If glass is newly installed, the side with potential debris must be identified...which can be tricky. The "tempering" stamp must be located and, depending on the type of stamp used (sand-blasted or porcelain stamp), the side of containing potential fabrication debris can be determined. In addition to visual identification, fabricating debris can also be identified if/when a “white noise” (think light static sound) is heard during normal scraping procedures. However, by the time you hear the white noise, damage may have already occurred.
What can be done to keep windows clean if they contain fabrication debris? First rule-of-thumb at LRWC is "DO NO HARM". As such, we do our best to identify potential fabrication debris and, if present, use non-abrasive tools to clean the windows. Instead of razors and/or steel wool, windows are pre-treated with plastic scouring pads (i.e., Scotch brite pads). However, using this process to achieve results similar to regular window cleaning is significantly more labor intensive (i.e., more expensive). Don’t blame the window cleaner...blame the glass manufacturers!