I am attempting to bulk prep some frozen convenience food and have determined that a standard Pyrex glass container would be ideal for freezing (non-liquid) meals (think burritos or tacos), but I want to ensure it is safe to induce a huge temperature swing, or if there is a better way to do this.

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    Pyrex is a special borosilicate glass that is specially made to handle large temperature extremes. You'll be fine. Commented Dec 23, 2014 at 21:48
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    jbarker : extremes but not shocks. Taking a dish and pouring boiling water in it will cause it to shatter. (so note : when making jello, there's a reason they tell you to heat up half the water, then add cold water ... I learned that lesson when I was in my teens)
    – Joe
    Commented Dec 23, 2014 at 21:51
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    It depends where you are. In Europe, Pyrex is a material, and probably able to handle temperature swings. In North America, it is a brand name rather than a material, and (aside from labware) not the same substance as in Europe. Not sure about in the rest of the world. Commented Dec 23, 2014 at 23:05

2 Answers 2


It not huge, it's just the difference from freezer to room temperature you are worrying about

E.g. -20°C to 20°C, is A 40°C shift. The shift was going to be 20°C to 100+°C anyway. There is no physical reasons why this would be anymore stressful

From room temperature you are raising it 80°C, from frozen you are raising it 120°C. Not a problem in the normal temperature range for glass

The freezing temperature of water (most common item in food) has no relation to the freezing temperature of glass etc

Pyrex and other glasses can be damaged if one part of them is instantly heated or cooled by a 100°C or so


Pyrex used to be made with BoroSilicate glass. Now some Pyrex is made with SodaLime glass, which isn't so tolerant of rapid temperature changes. So you need to follow the instructions for the dishes you have.

If in doubt don't heat Pyrex straight from the freezer. Rather eg transfer contents to another such dish already at room temperature for heating (if you can't wait for it to defrost naturally). http://www.consumerreports.org/cro/magazine-archive/2011/january/home-garden/glass-cookware/glass-cookware/index.htm

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    Yep, and sadly the american manufacturer is unapologetic and saying it is equivalent given correct usage, and is oblivious to the fact that correct usage is not what the customer is buying it for. Commented Sep 28, 2016 at 8:59

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