Chances are, somewhere in your kitchen, you have a version of the measuring cup pictured above — if not multiples. Pyrex-brand measuring cups are incredibly common because they’re made to withstand thermal shocks — that is, you can use one to measure hot water and, immediately after, cold water, and they won’t likely break. Try that with a regular glass and you’ll find it, in shards, all over the floor.
For decades, Pyrex was made of borosilicate glass, a special type of glass in which boron oxide is added to the mix. The added boron allows Pyrex to handle heat much better than typical glass, so Pyrex is commonly found in kitchens, laboratories, and in use with aquarium heaters (as the heaters are, necessarily, submerged in much cooler water). But in 1998, Corning, the company which made Pyrex, sold the brand to World Kitchen LLC. World Kitchen decided to stop the manufacture of borosilicate glass, and since then, Pyrex sold in the United States is made of tempered soda-lime glass, which does not handle heat as well as borosilicate glass does. (It may, however, be more resilient to drops.) In most cases that does not matter much, as tempered soda-lime glass is still pretty good at withstanding thermal shocks.
But it’s not great. In 2010, Consumer Reports (as reported by its quasi-independent blog, Consumerist), tested some Pyrex and and found that taking the newer glass out of a hot oven and placing it on a wet granite countertop yielded poor results: the glass shattered almost instantly, and violently so. And as Popular Science demonstrated, super-heating a measuring cup (in their case, with a blowtorch) and then adding just a drop of water has a similar effect — shattered glass, everywhere. Test tubes in chemistry labs are still made of borosilicate glass to avoid this very problem.
Of course, there are few cases where one is going to expose a Pyrex measuring cup to such extreme temperatures, so, if you do have a soda-lime one in your kitchen (and you probably do), there is little reason to worry — your recipes are almost certainly safe. Even the restaurant and food services industries can use the newer version of Pyrex without much concern.
But one industry was struck very hard by the switch: the crack cocaine trade. It turns out that turning cocaine into crack requires bringing the solution of water and powdered cocaine to a very high temperature and then rapidly cooling it. And for years, crack makers would use Pyrex — borosilicate glass ones, that is — to accomplish this step, successfully. The soda-lime glass alternatives cannot withstand the thermal shock.
As a result, the drug trade needed to find another way to obtain borosilicate glass. The unintended consequence of World Kitchen’s switch? An uptick in theft from an unlikely place. As PopSci so eloquently notes, “[the crack-making] industry was forced to switch from measuring cups purchased at Walmart to test tubes and beakers stolen from labs.”
The gf has a terrible habit of storing pots and pans in the oven. (Not the drawer underneath but the actual oven). I recently preheated it to 425 anticipating a Costco frozen pizza lunch. When It beeped that the preheat was complete, I found the shiny glass 9 x 13 casserole dish I'd scrubbed and put in the strainer the week before. She hid it in the oven even though I have begged her not too. I've cooked several frying pan handles as well, I just can't remember to look in there as it seems so silly to me. We have cabinets, use them!
Anyway, I grabbed an oven glove and placed the super heated glass pan in the mostly dry sink. I guess now I know why it exploded into a million tiny pieces. Sounded like the crack of a baseball bat hitting a home run. Scared the crap out of me and naturally the dog came to investigate. In keeping with my luck, she walked in the kitchen two minutes later and starts chastising me.
World Kitchen bought the name and junk glass formula and many people still think Pyrex is better but is same or worse then Libby et al they compete with. Very likely WK only bought the Consumer Brand and not the Glass Formula to make them. Corning still makes Laboratory Pyrex w/ borosilicate glass.
If buying used Pyrex... most new WK ones have no manufacturer and say "made in USA" Some old ones have Corning cast into the glass.
I believe newer WK bakeware handle "ears" are bigger and won't take Corning handles that clamps onto old Pyrex like this... The Cheap Glass won't take the load.
WK also bought Corelle brand but still makes same glass for many items. They actually stopped but many wanted the white glass so restarted making again a few years later. (WK Correlle is on How It's Made)
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
If buying used Pyrex... most new WK ones have no manufacturer and say "made in USA" Some old ones have Corning cast into the glass.
Interesting. I wonder what ours are? We have a 4 cup that has a teal tinge to the glass itself. I'm positive that one is a newer one as we bought it only 4 or 5 years ago. Our 1 cup however, the glass is thicker without the teal tinge. It doesn't have "Corning" cast into the glass but it does have "Corning" screen printed on it. The "P" from Pyrex is different on the 2 also. The 1 cup being a traditional looking "P" while the 4 cup is rounded.
Note the color and "Pyrex" font change.
What our 4 cup looks like.
What our 1 cup looks like.
[This message has been edited by Khw (edited 11-23-2016).]
Originally posted by RWDPLZ: Explains why mine is a different color than the ones my mother has had since I was a kid.
Corelle or Pyrex? Corning Corelle and Pyrex can stain over time might be part of any difference you see. WK Pyrex is very close to same tint. WK Corelle "traditional" plates/bowls are the same glass. But... Many Corelle cups are actually "White" Pyrex and will look different. Should be labelled as such on bottom. Why and Caution: Early Corelle small cups w/ closed handles are not microwave oven safe and can be big problems. Similar to this Corelle started 1970 and well before many people had microwaves. Later Corning made small Corelle cups open handles for microwave use...
WK change the Pyrex logo recently. Maybe other logos too. Even Corning change logos over time and might find books etc showing how the date by logo and such. Yes, WK updated design for many items as well.
Big problem is WK bought molds etc (if not the whole factory) and used them for years with cheap glass with little or no charge. You can find Pyrex bakeware so close to be identical except the "ears" are a big bigger w/ cheap glass parts.
I believe WK did get the whole factory making Corelle but in that case was a good thing. Why? In very short, Traditional Corelle Vitrelle is similar to how safety glass items are made. Meaning can't use a factory to make most other ceramic/glass items. Is why Corelle is very tough but can shatter to a thousand of pieces when dropped on hard floors. WK bulb Vitrelle® Technology
Note: Corelle brand is/was use for other ceramics too. They look ok but not nearly the same strength as Vitrelle.
Those I know I have as a lot of the Corelle plates. bowls and cups my parents had when I was growing up were handed down to me. It's not a complete set because of breakage over the years but my parents had them from as far back as I can remember, so at least the 70's. They are a blue design, but not the cornflower. I have some with the blue cornflower on them also but they are cooking vessels that use the handles like you posted a pic of above.
The pattern on the dishes.
[This message has been edited by Khw (edited 11-23-2016).]
Most Discontinued & Current Corelle Patterns--> https://www.microwavecookin...ontinuedCorelle.html Above is Snowflake Blue 1970-76. Parents had Spring Blossom Green/Crazy Daisy in 1972 (pictures above showing cup design) I have Morning Blue since ~83 most Corning, some WK because "outlet" stores still carries and add 28oz bowls and larger mugs. (Cups/Mugs w/ pattern are gone now. Replace w/ plain blue mug.)
[This message has been edited by theogre (edited 11-23-2016).]
Originally posted by Boondawg: Theogre always cracks me up. You just never know what you're going to hit on with him!
I mean, dishes?!
Mainly got mine thru closeout w/ very few choices back then just buy more as needed at outlets or at flea markets etc.
Growing up, Corelle was a lot better then Melmac Yup, Is a real thing that many watch ALF show knew Melmac Planet was a joke regarding the product and maker. Melmac was "The" dishes after WWII. Cheap and tough but after a few years they often look dull/dirty.
As a rule, I don't generally pay much heed to what the wife has in *her* kitchen, however after reading this topic I happened to note a large clear glass measuring cup on the countertop today. It has both "PYREX" and "Anchor Hocking" with the anchor trade symbol emblazoned on it's side.
Upon my inquiry, my dear spouse showed me her other 3 "PYREX" measuring cups, all of which have minor differences. I am further informed that the "newest" of these is at least 20 years old. Along with her various and sundry clear glass PYREX and white "Corning Ware" casserole dishes, these are apparently much treasured and frequently used by her. The pristine, almost *new* appearance of these culinary articles certainly belies their age and use.
[This message has been edited by randye (edited 11-24-2016).]
Originally posted by randye: As a rule, I don't generally pay much heed to what the wife has in *her* kitchen, however after reading this topic I happened to note a large clear glass measuring cup on the countertop today. It has both "PYREX" and "Anchor Hocking" with the anchor trade symbol emblazoned on it's side.
Pyrex is owner by WK (consumer use) and Corning (industrial/lab) and AH is another company. So Don't know how you find Both on a whatever.
AH bakeware etc is same/similar the WK Pyrex Consumer Reports had AH in same test and AH id a bit worse then WK Pyrex but both failed. Worse, After reading CR piece again... Corning make some consumer grade Pyrex w/ cheap glass too. A New Formula page:
quote
Sarah Horvath, a Corning spokeswoman, says Corning made Pyrex out of both soda lime and borosilicate at several locations before selling the U.S. business to World Kitchen in 1998, but provided no more details. P. Bruce Adams, formerly an executive scientist at Corning, says that borosilicate was still being used to make Pyrex when he retired in 1987.
