Hello, everyone.
Glad to be here at WCR.
I’ve come to talk about tempered glass, scrapers, and tempered glass scratch growth. (That is going to be huge.)
I’ve been involved in scratched glass issues for years.
Got a website for that scratched-glass.net
I’ve written a ton of stuff for the window cleaning industry, have managed to get published to the glass industry at Glass Performance Days, and heading back for more.
(Will explain more about that soon as I figure out where to post.)
I’m also the guy with the Picnic - be happy to talk about that, too.
Anyway, I’m happy to be here - and um, I’ve heard you need 5 posts before you post links and pictures - so could someone please ask me a couple of questions I can answer?
Which type of filters do you prefer r/o or forum? I’m just joking, I’m glad to see you here, and think your knowledge of Fab Debris will be a huge benefit to WCR.
Since before the turn of the century, I guess.
I worked at a glass fabricator for 3 years - back in the 70’s - before I started cleaning windows.
BTW all that tempered glass was fabricating debris free, and the glass company issued me a scraper to remove stickers and such.
I think having had that experience caused me to pay closer attention when Dan Fields started explaining the quality problem.
When a scratch penetrates the surface of glass, in addition to the immediate damage to the compressed area, there are tiny cracks radiating down and and laterally.
In annealed glass they tend to be harmless, but in tempered glass, as the area decompresses, the lateral cracks turn up toward the surface, creating a row of glass chips on each side of the original scratch track.
This extra wide scratch is much more visible, because it reflects so much more light than before it grew.
The thing is - it does NOT all happen at once.
At my site and on Facebook I have posted a pair of before/after pictures that I took of one segment of a tempered glass scratch.
(These pictures are on the cover of the next American Window Cleaner magazine.)
This scratch suddenly grew about 10x - while I was looking at it through a microscope - 45 minutes after taking the “before” picture.
It turned into a completely different scratch, right before my eyes. I heard it happen (probably because I was so close) - a tiny “poink” sound.
Apparently this happens all the time to tempered glass - but I don’t know of anyone who waits an hour or more to be sure.
That’s really interesting! So tempered glass scratches always look much worse as they age? Are you the first to identify this? Looking forward to hearing more.
Unlike aging people, tempered glass scratches don’t keep getting worse forever.
When all of those lateral cracks turn back toward the surface that should be the end of growth I’m describing.
This growth has been known to well read glass scientists since a 1993 paper published in the journal of the American Ceramics Society by Tandon & Cook.
It’s something any glass scientist worth his salt knows - you need to wait if you want to see tempered glass scratches at their worst.
I just happen to be the first window cleaner who gets it.