Pyrex

[Addie]

Are any of you aware of the fact that Pyres had changed the formula for their glassware baking dishes? Like so many companies today, they are looking for a cheaper way to make their product and to heck with the public. It seems to explode when it is in the oven, sitting on the counter cooling, or wherever it wishes to. There have been a few stories of baking dishes exploding in the owner's hands when removing it from the oven. I have the old formula Pyrex dishes but am looking to purchase some new Anchor Hocking pie plates. But they are hard to find. None of the local stores in my area carry that brand. Do any of you know of any other brand that is not owned by Pyrex since I cannot readily find Anchor Hocking?

 

[Andy M.]

Are you sure Anchor Hocking doesn't use the same formula glass as Pyrex?

You could also substitute stone ware pie plates and baking dishes instead.

 

[bakechef]

Anchor is made by Pyrex and uses the same formula!

Marienex (which can be found on amazon, and in some Hispanic stores), is still made with the Borosilicate glass which is much less volatile. Pyrex and Anchor are made with the soda lime glass.

One thing that I have noticed lately, is that Pyrex and Anchor are now giving their glass bakeware a greenish blue tint, to make it look more like the old borosilicate glass, seems sneaky to me.
I have gotten rid of all my glass bakeware and replaced it over the last couple of years with glazed stoneware or ceramic, both of these cook similar to glass bakeware, but are not volatile.

I've had a baking pan explode in the oven, it wasn't from "thermal shock", it had been in there for a while, the same thing happened to a friend about 6 months ago.

 

[betterthanabox]

I have a ton of this stuff, thanks for letting me know, so far so good, no blow ups!

 

[CWS4322]

I have a ton of pyrex. I got most of it at auctions or estate sales. Thrift stores might be a good place to look for the "old" formula pyrex.

 

[Effington]

My biggest problem with Pyrex lately is that my newer measuring cups don't seem to be dishwasher safe - or at least not the most important part: the LINES.

After about a year of regular use and dishwashing, I have a 2 quart measuring cup that is now useless because the lines and markings have disappeared. I have an even smaller one that barely lasted a couple months. Seems a bit ridiculous to me.

 

[PrincessFiona60]

I bought some stoneware baking dishes a few (6 years) ago that has been cracking in the oven. Thanksgiving day we heard an odd sound, but couldn't find the reason for it. When I was washing dishes, noticed my stoneware casserole I used for the dressing had weird markings in it, tried scrubbing them and they started to spread. Looked closer and discovered they were hairline cracks in the glaze and water was seeping in to discolor it. That must have been the odd sound, the cracking of the finish. Luckily it did not break like the last one. The last one had a chicken roasting it it and broke in a similar fashion.

 

[GLC]

The Pyrex thing is something of a trade-off. The old borosilicate glass (very old - the change began long ago) has a lower expansion coefficient than soda-lime glass, but soda-lime glass is mechanically stronger than borosilicate. So, while the soda-lime Pyrex is somewhat more sensitive to rapid temperature change (including what happens when people treat is as indestructible), it's less likely to break when dropped. So far as injuries, dropping glass cookware is significantly more often the cause than heat shattering. No kitchenware is designed to handle the stresses of chemical lab work, legal or illegal. It's popular to show videos of soda-lime Pyrex shattering, but you can easily shatter borosilicate Pyrex, too. No doubt, though, the motivation to change was cost.

When Consumer Reports tested the US brands, they both broke moving from a 400-degree oven to a wet counter (not an acceptable treatment of any glass dish). The pricey Arcuisine Elegance borosilicate mostly survived, except for the one that broke during practice after being a long time in the oven. In the same test at 500 degrees, everything broke... except for a very old piece of Pyrex. Too small a sample to say too much about, but interesting in terms of how much abuse they took. But unquestionably, the soda-line glass is more sensitive, as it expansion coefficient indicates. I would presume the also pricey Marinex borosilicate (Brazil) would perform about like the European.

 

[Addie]

I went to eBay and there are a ton of the old Pyrex and Anchor Hocking pie plates in all sizes. And they are relatively inexpensive compared to buying one in a discount store. Right now I have two that I have had for umpteen years. One has that ripple like edging. And I don't like it. It makes it hard to make a pretty trim crust. I would rather have a flat edge one. So I am going to go to eBay when I am ready to buy.

I went to Wikipedia to look up both Pyrex and Anchor Hocking. Pyrex sold the process to a country overseas, buy kept the name Pyrex and receives compensation for allowing the European company to put it on their product. Anchor Hocking is still made here in America. I do try to buy American when ever I can. Even if I have to spend a few cents more.

 

[dcSaute]

well, a couple of facts might be in order.

Pyrex is a trade name - it was originally "invented" and manufactured by Corning Glass - starting 1913-1915, depending on source.

as noted, Pyrex was originally made from borosilicate glass - which has a lower coefficient of expansion making it more resistant to failure when subject to rapid temperature change.

note the word "resistant" - borosilicate glass is not "unbreakable."
I've busted it - the old stuff - the genuine article - shattered it to pieces by too cold a water over the lava rocks in the Pyrex bread pan in the (pre-heated) oven . . . yeah, and I "know" better - one of my more dumber moments in the kitchen . . .

the Pyrex brand name was sold to World Kitchen in 1998.
according to World Kitchen, Pyrex is still made in their Penna. plant - not in China, the brand was not sold to an "overseas" company.

Anchor Hocking / et al had their own versions of glass cook/bake ware but not under the trademark Pyrex.

Corning Glass / Anchor Hocking / et al / has / had / have their own versions of (presumably both) borosilicate and tempered soda lime glass cook/bake ware. getting the "real truth" out of "companies" can be a challenging task.

exactly when the switch from borosilicate glass to tempered soda lime glass happened in the Pyrex brand is apparently a great secret. each and all of the companies has their own truth-evading spin doctors working on the problem.

borosilicate glass is inherently tempered - I worked for a company that made nothing _but_ borosilicate glass and every single item produced went through a tempering oven - a lehr, iffin' you need the jargon. borosilicate glass is chemically much more inert than soda lime glass - so it's used for all the medical stuff (Novocaine, anyone?) along with the bubbling, boiling, mad-scientist lab ware.

window pane glass is typically not tempered. when it breaks you get big pieces and shards. tempered soda lime glass - aka "safety" glass - fractures into little nuggets that will not slice open your jugular vein.

when glass objects are cast, pressed, spun, blown or otherwise "formed" - mechanical stresses remain in the "finished" shape. tempering heats the glass to nearly molten temperature and allows those mechanical stresses to relax/dissipate. generally speaking this make objects "stronger" because there are no "pre-stressed" areas that require "only one more straw" on the camel to shatter/break.

 

[GLC]

While it might seem attractive to try to acquire some "old" Pyrex in hopes of getting borosilicate, there's no reason to expect that anyone under the age of about 45 here (barring real collectors) can be sure that they've ever seen a piece of borosilicate Pyrex cookware, even in momma's cupboard. Perhaps someone somewhere actually knows which particular pieces of which post-1940 years are borosilicate, but if they are out there, they're not writing about it. I have doubts that the makers could tell you, at least not without some deep digging in the archives.

If Corning began phasing in soda-lime Pyrex in the 1940's, you'd have to know how to date pieces to pre-1940 to be sure. The fact that is years old and hasn't failed doesn't mean it's borosilicate. One would be hard put to tell the difference without very sensitive instruments or destructive testing. The two glasses have refractive indices in the same range, and the difference in density is very subtle. Soda-lime glass is fractionally harder. Spectral transmissions are almost identical.

I suspect someone reported their Pyrex failing, and someone discovered that there had been a change from borosilicate to soda-lime, and they didn't realize the change was long ago. Borosilicate Pyrex may fail above 450-degrees, and I imagine there have been plenty of failures from abuse that were just put down to the user having messed up and mishandled it.

Who has a piece of Pyrex they absolutely know is borosilicate, and how do you know? (Documented date before 1940 is one way, of course.)