When I was little, I accidentally shattered a glass cooking instrument due to applying far too drastic a temperature change to it. Since then, I've been a bit afraid of doing it again. Of late, I've been using a french press to make coffee; one that happens to be made of glass. Since I am now pouring almost boiling water into a room temperature glass object, I'm a bit worried it will shatter. Double so since if it does, I could have almost boiling water flowing from my desk to my lap.
After dozens of uses, there hasn't been a problem. And if there would've been one, I don't think they would have been allowed to sale it. But I'm still concerned about how cold it can still be used at. For example, if I leave it in my car on a cold night and bring it into the office, can it be used straight away?
So why doesn't it shatter and how cold can it be before I need to worry?
Demensions: roughly 20cm tall with a diameter of 10cm, if that is of any relevance.
Material: Glass, I assume a special kind that is better able to handle heat, but I don't kow the details.