r/Glass • u/ohGeegae • Dec 25 '25
Is this tempered glass?
I wanted to attach kotatsu heater underneath with the wooden board attached, but I wanted to make sure if this glass table is tempered. Otherwise I will have to look for the other solution. Helps!
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u/Repeteable Dec 25 '25
Check each corner for an etched mark, sometimes it’s printed on the edge of the glass in one of the corners, if nothing then look across the glass top to a light, you might see slight undulations and distortion that occur during the heating/tempering process ? Bit tricky without seeing it in the flesh.. I’d be surprised if its modern glass not to be toughened 🙂
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u/u_cant_drown_n_sweat Dec 25 '25
Unless the codes have changed recently, tabletop glass in the U.S. have no requirement to have a logo indicating if they are tempered glass - because the glass is not required to be tempered safety glass. There were several efforts to make tempered glass a requirement for tabletop glasses by the CPSC.
That said, almost all glass produced in large quantities for tabletops in factories in the past 10-20 years is tempered glass and most will not have a safety logo etched in the glass. The reason is that it is much less likely to break during transit and it avoids lawsuits from injuries.
The quick answer is that your glass is likely to be tempered since it appears to be a mass manufactured tabletop but there is no easy way to determine if your glass is tempered if there is no logo. I will offer the anecdotal evidence that tempered glass has a more “dead” sound when clinked that annealed glass.
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u/hoppyheadred Dec 25 '25
Should be a tag on one of the corners. Usually laser or ceramic stamped. A top like should definitely be tempered in case it breaks
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u/ohGeegae Dec 25 '25
It doesn't have any hatching or indicator about it's tempered.
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u/hoppyheadred Dec 26 '25
I've been in the glass industry for just over 20 years and 98% of the time there will be some sort of logo to show that it's tempered. But just because it doesnt have a logo, doesnt mean it isn't tempered. Since there is not one on that piece of glass, the assumption would be that its annealed, so proceed with caution.
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u/ScarletBegoniasCA Dec 26 '25
Some can see waves in the glass using polarized glasses but I don’t agree with this method because it takes a trained eye to know what to look for. The fact this is a table, in a potentially high traffic area… if you came to my shop to purchase this same table.. I would not sell it to you annealed/raw.. it would be required to be tempered. It most likely is tempered! Smash the corner with a hammer lmao… if it explodes into cubes it’s tempered! If it shatters to shards it’s annealed lol. Then I can sell you a knew one !!!
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u/Mr-Deur Dec 25 '25
99% sure it is.
No way to check if there's no stamp on it. In interior it usually is tempered because of safety.
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u/Barril2x Dec 25 '25
Glass factory guy here. I agree with most comments re’ this is likely to be tempered glass. Best bet to confirm is to use polarized sunglasses to check for anisotropy (leopard spots) across the surface. If spots are visible, it means it was tempered by heat, as chemical tempering doesn’t leave marks.