Wow ….
Never had this happen before.
Installing a two panel frameless glass bi-passing shower door over a bathtub today and one of the panels literally exploded in my hands as I was hooking the rollers up onto the track.
Quite a surprise to be left holding a handfull of glass shards in both hands and standing in a pile more of them!
Simple air-sealing measures and spray-applied sealant lower energy bills and increase comfort without the need to tear the house apart.
"I have learned so much thanks to the searchable articles on the FHB website. I can confidently say that I expect to be a life-long subscriber." - M.K.
Dig into cutting-edge approaches and decades of proven solutions with total access to our experts and tradespeople.
Start Free Trial NowGet instant access to the latest developments in green building, research, and reports from the field.
Start Free Trial Now
Replies
cool... similar thing happened at our office building some time ago - 1/2" tempered glass just disintegrated. No one could believe it was spontaneous (layoffs not that long ago), but your story is proof that it can happen!
Apparently the tempering process builds in a tendency to break that can manifest itself unexpectedly... anyone have more information on that?
A scratch on the glass surface will weaken it . if it is deep enough the glass on the inside is under pressure and will explode the panel . A slight bend ,bump, or viberation could cause the glass to crumble . I learned about tempered glass at UHK , Abuddy of mine wanted a chevy bowtie on the rear glass of his vega . We ducttaped it up cut the pattern and started blasting . All of a sudden the glass sagged . The ducttape held most of the crumbs together. I later did a mustang on the sunroof of a f*rd mustang , made sure that I did not etch to deep, turned out great.
Actually, as was implied in another note here, tempered glass is rather vulnerable in certain circumstances. For instance, you can take a small tool and tap the *edge* of a piece of tempered glass and shatter it quite easily. You can take a center punch or other pointed tool and tap it pointed end into the glass ever so lightly and reduce the glass to a thousand shards.
In my case, in re-fitting the panel for the second time, I had let it slip and it landed on the bottom (metal) rail extrusion. Thus I *don't* think I damaged the glass in that operation. In re-fitting it from its now somewhat cranked position, I don't recall having put undue bending stress on it but it was, stressing the *was* (grin) rather heavy so perhaps I was pushing more than I thought.
When the guy loaded the carton on the truck at the glass shop he flopped it in flat on the truck bed. I said "shouldn't I carry this standing up"? - he replied that the glass being tempered he could stand on it an it wouldn't break. But also reiterated the fact that chipping on the edge, etc., would be the end of it.
Thank heavens tempered glass does what it's supposed to do or there would be a huge pool of blood to clean up off that lady's bathroom floor!
...........
Dennis in Bellevue WA
woodnut@anatechsys.com
When I build a fire in the fireplace, I like to have the flames licking at the smokebox. I build it big and hot. Two years ago, cold March night, the flames were soaring. Standing back admiring, my jaw fell when the right tempered glass door exploded into many little pieces. (It was a custom arched top door, but only cost $90 to replace.)
What I think happened, was that the interior of the firebox heated up so fast, that the delta T (difference in temperature) across the door caused a difference in expansion rates between the inside of the glass and the outside, the stress manifesting itself in a puddle of broken glass door pieces.
Or maybe it was just scratched.
I never met a tool I didn't like!
Did the same thing years ago burning pine scraps in a spec house with newly installed fireplace. The pine just burned so fast and hot the glass couldn't take it and shattered.
BIL said it's fairly common for crews to do this in newly installed fireplaces in a house when the HVAC is not quite done yet..."It's cold in here, let's burn some of those scraps...."
similar thing happened to me a coupla years back ....
trying to rig something I knew wouldn't work ....
I "knew" ya couldn't drill tempered....
for some reason ..in the heat of stupidity ..I thought ..."Well, if I can't drill it, I'll juts use my tile/glass bit....."
Then .... to confirm my stupidity .....I thought ..I'll just do a test ....because we all know ya can't drill tempered ... so I tried a light drilling.
I was a bit surprised....seemed to be working ....I actually convinced myself I could drill tempered...with the special bit .....right up to the second the over glass shattered!
Scared the sh!t outta that poor little dog that was following me all around!
I learned two things that day ...U really ....really ....can't drill tempered.....and some older model ovens have really ...really expensive glass doors!
Even the appliance parts guy was shocked at the price....I picked the door that was 2 to 3 times the usual cost. I think it was over $200!
So what'd the shower door cost ya?
Jeff
Buck Construction Pittsburgh,PA
Fine Carpentery.....While U Waite
I can shed a little light on what happened with the shower door. I worked as an engineer on a tempering process for about two years. It's not a long time, and I'm not a ceramic engineer by training, so my knowledge is limited.
There are several methods of strengthening glass. The most common is thermal tempering, which is what is used for architectural and vehicle glass. During thermal tempering the glass is treated in such a way as to draw the surface into compression. The surface is held in compression by tension in the core.
To picture this, I'll try an analogy. (I'm making this up on the spot, so I don't know how well it will work!) Imagine a row of 2" x 2" squares of 3/4" thick material layed on a bench. At each end is a 2" x 2" square, but 2" thick. On top of the thin squares is a spring attached at each end to the thick end blocks, then on top is a second layer of 3/4" thick blocks. The spring in between is streched, pulling the end blocks tight, compressing the two layers of thin blocks together. The 3/4" blocks are in compression, and the spring between them is in tension.
Now imagine instead of two rows of blocks there were two checkerboards of blocks, with springs running in both directions between them. That's what tempered glass is like, compression on the surfaces, with tension in the core pulling the surfaces into compression. With strong enough springs, the whole assembly is really tough, and would act like a solid board.
Because of the compression, it would be hard to force something down between the blocks because even though they are not attached, they are being pulled together very tightly. But, if you did, and cut one of the springs, pow! the whole thing would "explode". The same thing happens in tempered glass, except there are no individual springs, the entire core is one big spring. So the whole thing shatters at once, more like popping a balloon.
In thermally tempered glass, the compressive layer is about 1/4 the thickness of the sheet. So, for 1/4" glass, that would be roughly 1/16". Any scratches or checks that are shallower than this will not rupture the glass. But, if you go into the tensile core, even the tiniest little bit, the whole thing shatters.
I suspect the edge of the glass had a defect in it, possibly a speck of foreign material, but very much more likely the edge got bumped and checked, and with a little bending it became just deep enough to penetrate the compressive layer.
The compressive layer explains why someone was able to start drilling and think everything was ok. It would be ok for roughly the first 25% of thickness, then, pow.
Edited 9/22/2003 11:51:07 PM ET by WAYNEL5
Awesome! Thank you!
I am impressed by your explanation.
Excellent explanation. Thanks. Never had it explained in any detail before.
I once tried to cut a small piece of glass out of a piece I had laying around. The piece was about 2'x 2'. What a surprise to find out it was tempered. And what a mess.
Excellent explanation! Thanks.
Mike
i once read of a bizarre phenomenon called Prince Rupert's Drops (?). they're made by dripping molten glass into oil which creates a highly tempered drop with a tail- kind of like dripping hot sugar into cold water when making candy. anyway, these drops are so tough you can beat on them with a hammer (i suppose with some limits) without breaking them, but if you clip or snap the tail off they explode.
m
This was a great explanation. Geesh, learn something new every day. One thing I'm curious about......
I was at my mother-in-laws house once and all of a sudden POW. The tempered glass doors of her TV entertainment center just exploded for no reason at all (now her house is haunted and we suspected a ghost or paranormal event, but I later learned tempered glass has this spontaneous tendency). The thing is, all those thousands of pieces fell to the floor and laid there snap, crackling and popping, jumping around like popcorn for a minute, maybe two, or three, not sure.
So what causes it to behave like popcorn after it explodes?
The glass is still releasing it's stored energy. The amount of energy stored in the glass under tension and compression is considerable. After the initial pow! the pieces still have some energy left. It simply takes a few minutes for the tiny fractures in those pieces to grow to the size that causes them to break the rest of the way suddenly.
> ....So what'd the shower door cost ya?
Actually, the door mfr covered it under warranty. Seems like this isn't an unheard of thing to happen. I lucked out, bouth physically and financially.
...........
Dennis in Bellevue WA
woodnut@anatechsys.com
LOL.....were you walking in my world today?????? The carpet layers were 2 1/2 hours late getting there.
One of them decided that it was a requirement to step into the freshly painted bath-tub, oops......wait there is no carpet in the bathroom, let alone the tub.
Then 3/4 of the way into the carpet job they realize, OOOPS we don't have enough carpet to finish the house! We are short the carpet for one room......wait and we don't have anymore of this one.....
So I send the HO with the carpet man, whom she chose, to figure out the carpet nightmare......then the helper comes and says I need you in the backyard. Seems the cable company is installing new wires on the pole and managed by some fluke of luck to clip the phone lines coming into the house I am remodeling! I told him fix it, he says he can't I should call the phone company......LOL...I told him I did not clip the wire!
Is it miller time yet? And WHAT WAS I THINKING????????? I want ot be a general contractor WHY!?!?!?!
Theresa-Honeydoos
Our tilesetter told us about a glass installer who was putting the finishing touches on a frameless door enclosure. He was tightening the big chrome D handle with an allen wrench while sitting on a bucket. He accidentally dropped the allen wrench and it bounced up, hit the bottom edge of the door, and the door exploded. The D handle fell, cracked the marble tile floor, bounced back up and hit him in the forehead, opening a gash that required stitches.
so you thought you were having a bad day ?
carpenter in transition
Wow, what a visual!
Mike
In the early 70's I had glasses that had glass lenses. They were "hardened" variety.
Whilst just "standing there" one day, one of them exploded. After a trip to Dr.
to get bits removed from eye, concluded to never get glass lenses again...
Probably same thing as with tempered glass...
Bud
My wife did this a few months ago. We were carrying up the panels for a shower enclosure. I took the door up, set it down, no problem. My wife carried up one of the side panels, set it down very carefully, and started to pivot it to the side. On a textured tile floor. I think the weight ended up on one point, and that's all it took.
I knew exactly what had happened. A year or so ago I was cleaning my pinball machine. I pulled off the metal lockdown plate, and the glass started sliding out, so I put the edge of the lockdown against the glass to stop it.
Bam.
Took about an hour of shop vac time to get it cleaned up.
Thanks to everyone who took the time to share their experiences with similar misshaps. I've been gone a while and couldn't respond sooner -
It's good to know I'm now the only one who's had this happen. I've installed a number of shower and tub enclosures in the past but this was the first framless one, at least for a client. I'll definitely know to take more care with the edges from here on!
...........
Dennis in Bellevue WA
woodnut@anatechsys.com