What is Tempered Glass?
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Tempered glass is one of two kinds of safety glass regularly used in applications in which standard glass could pose a potential danger. Tempered glass is four to five times stronger than standard glass and does not break into sharp shards when it fails. Tempered glass is manufactured through a process of extreme heating and rapid cooling, making it harder than normal glass.
The brittle nature of tempered glass causes it to shatter into small oval-shaped pebbles when broken. This eliminates the danger of sharp edges. Due to this property, along with its strength, tempered glass is often referred to as safety glass.
The thermal process that cures tempered glass also makes it heat resistant. Tempered glass is used to make the carafes in automatic coffee makers and the windows in ovens. Computer screens, skylights, door windows, tub enclosures and shower doors are more examples of places you will find tempered glass. Building codes also require the windows of many public structures to be made of tempered glass.
Automobiles use a different type of safety glass for the windshield and tempered glass for the back and side windows. Windshields are made from laminated glass, which sandwiches a sheet of plastic between two panels of glass. When the windshield breaks, the glass panels stick to the plastic film, rather than falling away to possibly injure the driver or other passengers.
Tempered glass breaks in a unique way. If any part of the glass fails, the entire panel shatters at once. This distinguishes it from normal glass, which might experience a small crack or localized breakage from an isolated impact. Tempered glass might also fail long after the event that caused the failure. Stresses continue to play until the defect erupts, triggering breakage of the entire panel.
In recent years, acrylic has replaced tempered glass in many applications in which heat is not a factor. Acrylic is 20 times more impact resistant than glass and does not shatter like tempered glass. Instead, acrylic dents if the impact is strong enough. If the force is sufficient to cause acrylic to fail, it will crack without shattering.
Acrylic is also half the weight of glass and has many other advantages. However, it is flammable. Therefore, you won’t find an acrylic coffee carafe or oven door.
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30
One company tells me that tempered glass is all you need for overhead panels in a sunroom and another company tells me that it must be tempered on the outside and laminated on the inside. Which is correct? - anon64297
26
Is tempered glass more resistant to heating/cooling damage than normal glass? - anon50984
25
I have a dual tempered slider that the outer crazed a couple of weeks ago. Will have it repaired, have estimates - but money is tight Duh! How long might I expect the glass in this door to stay put as long as I don't touch it? Yes, I understand there are many factors - but a guesstimate will do.
It poses no danger to the inside of the dwelling and we hope the inner panel doesn't duplicate, and no pieces have come away - just crazy.
M
- anon48892
24
Can tempered glass be used safely in wood burning stoves and fireplace screens? Will extreme temperatures cause it to "explode?" - anon47622
22
is tempered glass expensive? - anon45679
21
What is the u factor and shading coefficient of 10 mm clear tempered glass and grey tint/bronze tint tempered glass? Thanks. - anon42286
20
you cannot cut tempered glass. - anon40340
19
where can I purchase two pieces of 18" x 25" x 95" (5mm) pyroceram glass? - anon39623
18
Would it be a bad idea to clean my tempered glass refrigerator shelves in the dishwasher? Will the temperature change from fridge to hot water possibly break them or should they be allowed to warm to room temp before putting them in the dishwasher? I just hate the job of hand washing them. - anon39492
17
Can tempered glass be cut without breaking it. - anon36054
16
Outside table tops that are tempered shoud be fine during the winter. The only concerns would be thermal shock (putting a pot fresh off the stove on to the glass), or if the unit is a metal frame the metal may contract and pop the table top.
J - wholesale glass distributor - anon35627
15
Anon28649, the glass should pass the safety standards. Should be tempered, heat soaked and laminated. -Pinoy - anon33730
14
Is there any difference between tempered glass and toughened glass? If yes, tell me what. - trebickailir
13
I was at a shopping center that had a glass balustrade all around the food court on the second floor that just cracked, and fell down onto the lower levels. It had BS class A written on it, this appears very dangerous. If it is so brittle children could run straight through it and fall to their death. Is it normal practice to have a glass balustrade for protection at such height and what is the correct glass to use? I will be forwarding a complaint to the building control officials in the local council authority before some kid dies from the stylish, but dangerous glass. - anon28649
12
can tempered glass and acrylic filters ultra violet radiation? - haykal
11
To: anon25940 - Tempered glass will reveal stress waves when you view it through a polarizer. Besides breaking the glass, that's the only way to determine if it is tempered.To: smaltzl - Once a glass is tempered, that it, you cannot cut it.
- anon26817
10
How can you tell if it is tempered glass or not? - anon25940
9
I have tempered glass panel from a sliding glass door. If the frame is removed, can that panel be cut to another size?
- smaltzl
8
what is the difference between tempered glass & low-e temp annealed glass, argon filled? - garyc
7
With respect to the unexpectedly broken glass, my guess is that the problem probably had to do with a structural defect in the window frame that exacerbated a previous defect in the glass itself.
It is possible that the glass broke because it was not properly fitted to its frame. Without proper fitting, repeated cycles of expansion of the frame (which might be wood or metal) has built up stress in the glass. A slight disturbance, such as your opening the window shade, might put the final "nail in the coffin" for this window. Also, sometimes older casement (hinged windows that can open like a door) windows are not properly fitted into the window sash. Thus, you might close the window and flex the whole frame, thus putting unexpected stress on the glass.
- anon13790
6
I had a strange thing happen to me. I lower the shade to my bedroom window each nite, a window which gets direct sunlight each morning. One morning as I raised my window shade, the window cracked.
The window was never stuck by anything from either inside or outside. Please explain the cause of the glass break. - anon11575
5
what is the thermal conductivity of tempered glass with 6mm of thickness?(tempered glass = side windows of cars and rear window) - anon11268
4
Glass balcony person...if anyone has cleaned with "Dupont 409", I heard, but cannot verify easily, it has an acid in it that etches glass...
If glass is etched...maybe it can be repolished or frame treated back to shiny? or possibly laminated with a polymer... I do know the olde University of Chicago library had glass blocks for flooring, which was fun...and helped distribute light but over the decades of weary scholarship had all gotten scuffed beyond shiny. Last stop for long-wearing glass issues: Dark Mission--The Secret History of Nasa by Richard Hoagland. Apparently there are very durable types of glass (anhydrous glass). best wishes, Sparky-Foam - anon10645
3
I have a tempered glass balcony and it seems as though I can't get them as cleaned as they first were put in. Lots of film on them and tried cleaning with just about everything...
Please help with different options.. - anon8126
2
I have tempered patio furniture, can it stay out during winter? - kathyp
1
i have an outdoor patio table made of tempered etched glass and i'm wondering if it's safe to leave it out all winter, will the glass break if it freezes? - anon4980
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Written by
R. Kayne
Last Modified: 06 February 2010
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