What would you like to do?

Why does thick glass cracks when hot water is poured into it but thin glass does not?

already exists.

Would you like to merge this question into it?

already exists as an alternate of this question.

Would you like to make it the primary and merge this question into it?

exists and is an alternate of .

I'm answering this question from the perspective of a glass artist...

Thin glass warms up more quickly because it IS thin and not subject to differences in temperature within the glass itself that cause internal stress. With thick glass, the surface may be hot, but the center may still be cold, and the difference in temperature will cause it to shatter or crack.

However, to answer your question, it is most likely related to the TYPE of glass that was used to create the product and not the thickness.

For those of us who work with hot glass (cast/torch/fused) an important concept is one of thermal shock. Glass for fusing is assigned a number called a "Coefficient of Expansion" that relates to how much the glass expands and contracts when you heat it to its melting temperature and cool it back down.
Coefficients of Expansion Beadmakers (lampworkers) who melt rods of glass use "softer" glass with COEs of approximately 104 (Moretti). This type of glass melts at a lower temperature and is fairly easy to work with. Glass fusers usually choose between one of two standards...System 96 (96 COE) or Bullseye (90 COE). Pyrex, another familiar glass (Corning 7740 Borosilicate), has a COE of 32.5. It is worked at a much hotter temperature. The higher the COE, the more that the glass expands and contracts. The lower the COE, the stronger the glass, and therefore less likely to break.
If you've ever watched a glassblower...the kind you used to see at the mall or the county fair, they most likely used Pyrex for its durability and resistance to thermoshock. Also, you cannot mix these different types of glass because as the glass cools it contracts at different rates and causes stress within the glass. This leads to immediate or even future breakage.
More Info About Pyrex... So a little more about Pyrex, which is very resistant to breaking...its predecessor was a low-expansion glass originally invented by Corning Glass Works for the railroad industry. The railroads needed shatterproof lantern globes that wouldn't break when hit with rain or snow. Corning found that the demand for replacement globes went down significantly after the introduction of this new product.

So how did Pyrex come into existance? The wife of a Corning scientist, Bessie Littleton, was having problems with a casserole dish breaking, and made a request to her husband to bring home samples of this new shatterproof glass. He brought home two samples of sawed-off battery jars, and she cooked a sponge cake in them. She found that the cooking time was shorter, the cake was uniform, and most importantly, they didn't break. In 1915, Corning introduced Pyrex bakeware to the world. Check out the article posted at the end of this answer.


Thanks for the feedback!

Why is it that your mother put a spoon in a glass before pour the hot water?

To cool it.   My mother didn't, actually, but if one's mother did, it was probably to start cooling it right away to reduce the chance that the glass would crack. The spo

Why will hot water poured into a drinking glass be more likely to break the glass if the glass is thick?

The outer side of the thick glass expands at a different rate from the inner side. This sets up a tension that is different from the other side. So it cracks. Most drinking gl

Why do an empty glass cracks when you pour very hot water into it but it does not crack if there is a metal spoon in it?

When we pour very hot water into an empty glass, the inner surface of the glass will expand as matter expands when heated. But the inner surface of the glass will expand more

Why does glass crack when hot water is poured into it?

When heat is applied to something, it tends to expand. When you  pour hot water into something made out of glass, only the inside  dilates, and the outside doesn't, since it

Why does a thick glass break than a thin glass when hot liquid is poured?

When you pour a really hot or really cold liquid into a glass, the sudden expansion or contraction will cause it to break. This is especially true with thicker glass because t

What makes glass to break when hot water is poured in?

The expansion of the glass makes it break (the inside of the glass, which is in contact with the hot water, tries to expand more than the outside; the tension makes the glass

Why does a glass tumbler crack when you suddenly pour hot tea into it?

When we pour very hot water into an empty glass, the inner surface of the glass will expand as matter expands when heated. But the inner surface of the glass will expand more
In Physics

Does glass break when you pour hot water in it?

Very cheap or extremely thin glass can, yes - that's why modern  heatproof glass was developed.   Any glassware designed for kitchen use is safe from breakage if hot  li
In Uncategorized

Why does hot glass crack when kept in cold water?

As things heat up they slightly expand. When they cool they get smaller. So, if you take a brittle substance like glass and heat it up it will expand. But, if you rapidly cool