Since Pyrex explodes at times, what to replace it with?

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vilasman

Senior Cook
Joined
Sep 6, 2004
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Since pyrex has a tendancy to explode un predictably what are you all going to replace it with? Or are you just going to be really careful with it
 
I have never had Pyrex explode. The times I have heard of that happening were due to thermal shock, most commonly putting a Pyrex dish right out of the oven in a puddle of water.
 
It's not unpredictable at all. Thermal shock as already noted. Put it on layers of a dry towel when hot or a wooden trivet. A cast iron trivet might also cause thermal shock
 
so while nothing is absolute, you can pretty much prevent it from exploding. What concerns me is that my wife does things pretty much unconsciously, so she could take something from the ice box and try to put it in the oven.
 
Let me explain the physics of this. As materials, be they glass, ceramic, metal, liquids, etc., heat or cool, they expand or shrink. It is this quality that creates the explosions. Glass is an insulator. It doesn't accept or transfer heat readily. When you take glass that is very hot, or very cold, and immerse it into an environment that forces rapid temperature change (placing a hot casserole dish onto a water covered counter top where the water rapidly cools the material that it touches) the glass that is forced to rapidly change temperature contracts. But the heat isn't dissipated from the whole container. Only the outermost skin of the glass is rapidly cooled. Glass and ceramic have very little elasticity and the rapidly cooling surface contracts much faster than the iner layer of the material, creating huge stress until the glass shatters.

Think of a bi-metallic strip. It is made of two metals, with different expansion rates, welded together. When they are heated, one strip expands faster than the other one. This causes the strip to bend as one piece of metal pulls on the other for the length of the strip. That's what makes an electric toaster stop toasting. The strip finally bends enough so that it trips a latch that turns off the toaster and releases a spring loaded bread holder. That same bending action is forced onto a glass or ceramic dish when it is very hot or cold, and is subject to extreme temperature change. The outside surface expands or contracts too quickly and tries to bend the whole dish. That force becomes strong enough to shatter the glass.

Pyrex used to be made from a special formulation of glass that transfered heat throughout the whole of the container much more quickly, and thus prevented the thermal shock problem. But now, they just use tempered glass as it's cheaper.

Believe it or not, in extreme cases, cast iron can be made to shatter in the same way that ceramics or glass can shatter from thermal shock. But it takes extreme temperatures to do it. I have heard of it happening though.

Be careful with any pot or pan, no matter what it's made of. I have seen the bottom of my stainless steel pots expand and suddenly warp inwards when placed on too high a heat, with little liquid in them. This caused a loud bang when the pan bottom popped upward and threw water into the air. The bottom got bigger, but the sides didn't change thier circumferance, and the only direction the metal had to go was up, suddenly and with violent consequences. Fortunately I wasn't very close and didn't get hit with hot water.

Know a bit about your cooking tools and you will be safe. All pots, pans, and cooking vessels have strengths, and weaknesses. It's best to knowsomething about the properties of the tools you use so that you get safe, and effective results with them.

Seeeeeeeya; Goodweed of the North
 
goodweed... I thank you for the physics refersher course.... all jokes aside but i was an electrical engineering major... I know the physics.

I have a really cute and intelligent wife... who has argued with me about the sun setting in the east....

And one day she will take a dish from the icebox and put it on the stove and it will ka-pluey and she will look at me all sweet an innocent....

And i will say didn't I tell you not to do that

And she will continue to look at me all sweet and innocent...
 
>>Pyrex used to be made from a special formulation of glass that transfered heat throughout the whole of the container much more quickly, and thus prevented the thermal shock problem. But now, they just use tempered glass as it's cheaper.

this is incorrect. "Pyrex" glass is a formulation of glass that has a low coefficient of thermal expansion.

"tempered glass" is altogether a different concept.

the "coefficient of thermal expansion" is the amount of expansion a material experiences per degree of thermal difference.

"thermal difference" - that's about about taking it directly from the freezer to a hot oven.

"amount of expansion" if you stretch (any) material past its limit, it breaks. so a glass with a high expansion per degree of heat change will more rapidly expand/stretch to the point where the elastic limit of the material cannot withstand the strain - and then it breaks.

yeah, I used to work for a glass company.....
 
i have some visions , have had for many years, nary a problem. the only time one exploded on me, i was roasting a duck. pulled out to check and the air hit that super hot duck fat. it shattered. scary
 
I have Visions too and have abused them horribly. I just wondered what kind of glass they were.
 
>>Pyrex used to be made from a special formulation of glass that transfered heat throughout the whole of the container much more quickly, and thus prevented the thermal shock problem. But now, they just use tempered glass as it's cheaper.

this is incorrect. "Pyrex" glass is a formulation of glass that has a low coefficient of thermal expansion.

"tempered glass" is altogether a different concept.

the "coefficient of thermal expansion" is the amount of expansion a material experiences per degree of thermal difference.

"thermal difference" - that's about about taking it directly from the freezer to a hot oven.

"amount of expansion" if you stretch (any) material past its limit, it breaks. so a glass with a high expansion per degree of heat change will more rapidly expand/stretch to the point where the elastic limit of the material cannot withstand the strain - and then it breaks.

yeah, I used to work for a glass company.....

Pyrex used to be made from borosilicate glass, if I recall. And you are correct in that it expands more evenly. But the bimetalic strip analogy is still correct. I'm not sure if the glass transfered heat more quickly or not. But the result is still the same. I was at least close.

What would be too cool would be to find bakeware made from fused quarts glass. It can be taken to 1100 degrees and imersed in cold water without damage due to thermal shock. That would be amazing.

Seeeeeeya; Goodweed fo the North
 
>>from borosilicate glass

ayup! still is I imagine [g] the coefficient of expansion has units of how many inches per inch the material expands per degree of heat change - borosilicate formulations are on the low end of the scale.

the "exploding trick" is most associated with some manner of damage - a small nick or chip that becomes a stress riser - and when the right amount of thermal shock/stress comes along - ka-blewie. it can happen either 'through' the thickness of the glass (the bi metal is an apt description) or in a 'lineal' dimension.

this is easily 'demonstrated' - but hard to 'prove' after the fact because. . . well, it's just that there's a lot of little pieces.....

not that 'manufacturing defects' don't exist - frosted areas, dimples, orange-peel, mold marks, folds, inclusions.... lots of stuff can become a stress riser.

>>cast iron can be made to shatter
if you've played around with liquid nitrogen, it's good for making all sorts of things shatter.
 
I have an 11x15 Pyrex casserole I've had over 20 years. I haven't babied it at all. I just always used a trivet to place it on. The troubles I've heard about often came from taking a hot Pyrex dish from the oven and set on the stove burners, either hot or cool. My trivets are Kitchenaid plastic ones, I make sure they are not wet.
 
I have a large butcher block cutting board that I put on the counter next to the stove when I'm baking or roasting with any of my Pyrex or Corningware dishes. It protects the solid surface countertop and the dishes from any liquid spillage. The only Pyrex stuff I have is a couple of 9 x 13 pans.

I used to have an oval Visions Dutch oven style casserole. One day it came out of the oven with a crack all the way around the bottom. I don't even know what was holding it together. It did not go into the oven cold (just room temperature), and the oven was just at 325°. Since then I've been a big fan of Corningware casseroles, which I've never had a problem with.
 

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