Tempered vs. Untempered Glass


The Case of the Broken Glass Tabletop

Good Morning,

I have a glass table (metal base) with 1.30m (4.3ft) length, 75cm (29.5in) width and 1cm (0.4in) thickness. Yesterday a massive glass sphere fell of the shelf from a height of 1m (3.3ft) and broke the glass tabletop, made of common glass.

I have had this table since 2009 and never had an accident with it. My main question is, which glass has the best impact resistance? I don’t want to spend more money on tempered glass if it is the same resistance of common glass. But if it is stronger, I will.

My concern about the strength of the glass type is because my monitor, sound system and desktop is on the table ( total value of $1,500).

Thanks for your time and have a great day.
Sincerely,
Felipe M.

Answer Regarding Tempered vs. Untempered Glass:

Hi Felipe,

Thank you for contacting the Glass Detective with your question about whether you should use tempered glass or what you refer to as “common” glass for your office table. You question whether the tempered glass is less likely to break from impact than “common” or what we can call non-tempered glass. The simple answer is yes, the tempered glass is much less likely to break from impact … it is 4-5 times stronger than non-tempered glass of the same type and thickness.

However, tempered glass will shatter (explode) completely when it is broken and, as a result, items on it (when used as a table top) could fall off or fall through any area that did not have a solid surface underneath it. So there is a bit of a trade-off here. You could use a tempered/laminated glass combo which combines two pieces of glass by way of a poly-vinyl (PVB) inner layer. Then you would have the strength of the tempered where an object might impact it but if it did break, the glass would not completely fall apart and (depending on how much weight you had on it) most likely stay in place. The American Society for Testing and Materials (ASTM) actually established a standard for glass used on furniture that specifies it must be tempered glass in order to avoid injury in the event of breakage.

Glass.com has other articles about this topic and you should spend a few minutes reviewing them before you make a decision of any kind.

The Case of the Coffee Table Glass Top

How to Choose Between Laminated and Tempered Glass

Prices will vary depending on what you decide but as in all things, including glass, you get what you pay for. A reliable glass shop in your area can guide you through the selection process and hopefully even show you samples of the various glass types available to you. I hope this information is of some value to you and thank you again for contacting the Glass Detective.

-GD

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3 responses to “Tempered vs. Untempered Glass”

  1. Filipe should also look into giving his new and expensive piece of tabletop glass a protective layer of applied safety film (clear, shaded, frosted, patterned, etc.); they’re all available. A 7-12 mil material thickness would give superior impact resistance in that type of event, and applied to both sides, would indeed hold cracked or broken pieces of glass in place. This type of safety film could even save the glass from chips, scratches, scuffs & gouges from occuring in the first place.

  2. Good afternoon
    Am having a vanity build with glass am looking into using Tempered glass for the side and front can I used the same for the top?

    • Hi Gene,

      According to the American Society for Testing and Materials (ASTM), tempered glass should be used in furniture applications due to safety reasons in case the glass were to break. Tempered glass will usually break into small, rounded pieces whereas untempered glass typically is sharp and jagged. More information can be found by reading the ASTM F2813 Standard.

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