Because the glass is cold, when poured into hot water, the glass wall expands rapidly because of thermal expansion and cold shrinkage, but because the glass is a poor conductor if the glass wall is very thick, the temperature of the inner wall can not be quickly transferred to the outer wall, and the inner wall expands and enlarges, while the outer wall keeps its original shape, which will cause the outer wall not to accommodate the expanded inner wall and cause the glass to burst.
Glass cracking is very dangerous, splashing hot water may scald people, and cracked fragments may also cut people, so we need to pay attention to avoid causing the glass to burst in our daily life, so what are the ways to prevent the glass from cracking?
1. To prevent the new glass from cracking, boil the newly bought glass in hot water for ten minutes. After the glass is evenly heated, it will not produce strong pressure and will not cause the glass to break.
2. When pouring boiling water, you can put an iron spoon or stainless steel spoon in the cup, and then slowly pour the boiling water into the cup. So the cup won't burst. This is because when boiling water is poured into the bottom of the cup, it distributes some of the heat to the metal teaspoon of the good conductor before it has time to hot the glass (the bad hot conductor), so the temperature of the boiled water decreases, and it changes from boiling water to hot water, which does nothing to hinder the glass. As for the boiling water that continues to be poured in, it is not so scary for the cup, because the cup is already a little hot in time.
3. Glassware is easy to crack when holding too hot or too cold water, so you should avoid an environment where the temperature difference is too large. Usually, a temperature difference of more than 80 degrees will cause strong thermal expansion and cold shrinkage of utensils, which can easily lead to cracking. Unless otherwise specified, try to avoid using containers to hold water that is too hot or too cold. Before pouring hot water, you can pour a little bit into it, and shake the utensils so that the hot water is in full contact with them, so as to achieve the purpose of preheating the utensils, and then pour in the hot water, which can prevent the utensils from cracking due to excessive temperature difference.
Glass is a non-toxic and harmless appliance for daily use, but we should be careful to use it to avoid some of the dangers that may be caused by its own characteristics. Of course, you can also choose a high boron cup with a higher coefficient of expansion, which will be safer and won't burst easily.