I used to worry about this but there's not a meaningful difference if you have any care for the tools and basic precautions. Borosilicate glass also tends to be more dangerous when it breaks. I've broken far more pieces of glassware due to mechanical reasons than thermal reasons.

Pyrex doesn't have a maximum temperature limit in a kitchen environment if you are careful. Preheating the oven is the #1 way to prevent issues. If you put a piece of glassware in an electric oven without preheating it, you can create massive temperature deltas between top/bottom. I can get an iron skillet beyond 700F in my electric oven if I leave it in there while it's preheating for a set point of just 450F. If the heating element has direct line-of-sight to the cookware, you always need to be wary of radiative heating effects.

Just a note: The second “Pyrex” in the title should be all lowercase (“pyrex”).

Since the article is discussing the branding, this is relevant, as they use “Pyrex” in the article, to refer to “PYREX.”

In the UK PYREX cookware is always borosilicate. So it was a bit confusing to hear americans say how shit their "pyrex" glassware is.

Mind you, most of our oven proof glass is decent enough to be put in the oven and then dumped on a cold surface.

If you're interested in learning more about zero-expansion materials, Huygens Optics has a great video series on youtube: https://www.youtube.com/watch?v=qi8jmEbWsxU

I watched a video recently that dove deep into this as well[1]. It turns out there's not an easy way to figure out if it's borosilicate other than if it has "made in France" on it or if you know it was purchased in Europe. AFAICT, you can't really buy borosilicate Pyrex in the US.

The video does also show off a cool "mineral oil test" to tell the difference, but probably is only effective if you had something to compare it against.

My takeaway though was that I need to thrift some Corningware, though!

1: https://youtube.com/watch?v=2DKasz4xFC0

Relevant video from Ann Reardon's How To Cook That about exploding Pyrex (and the difference between all capitals and all lowercase): https://www.youtube.com/watch?v=YVbkDAw4aJs

Turned out that distinction isn't too reliable when it comes to determining whether a product used soda lime glass or borosilicate glass instead.

So there are three : PYREX borosilicate glass lab equipment, pyrex soda-lime glass cookware, and Pyrex borosilicate glass cookware made in France. Another childhood illusion shattered.....

If you're curious the only brand I could find easily purchasable in the USA that uses borosilicate glass is oxo. Their are some other results if you do a search on amazon, but I'm not very convinced those are really borosilicate glass.

In Germany borosilicate glass is called colloquially "Jenaer Glass" named after the city of Jena.

https://en.m.wikipedia.org/wiki/Jena_glass

I remember when I was doing A-level chemistry at school circa 1970 we were told always to check that any glassware we were heating up a lot (or might be very exothermic) had the PYREX symbol on it, otherwise bad things could happen. A bit later, almost everything was PYREX.

A recent video from the I Want To Cook channel on the topic:

* https://www.youtube.com/watch?v=2DKasz4xFC0

He references this FAQ from the Corning Museum of Glass (CMOG):

> The short answer is that the change from upper to lower case signified a re-branding of the trademark Pyrex® in the late 1970s but is not a conclusive way to determine, historically, what type of glass formulation the product is made from.

* https://libanswers.cmog.org/faq/398431

Has anyone written a better explainer about the difference? Corning's entry isn't that helpful. Particularly interested in the safety issues and practicality in terms of kitchen use.

Also, I'm told that IKEA's "MIXTUR" line of glassware is more Pyrex-like than actual Pyrex. Is that true?

The article is written like a low-grade blog spam, and yet it is corning.com.

They reference events out of order, etc.

It's some evil genius market segmentation on behalf of Pyrex management.

This sort of thing subverts the usefulness of trademarks. You buy from a traditionally upright company, but they just bait-and-switch you on the strength of their trademark and you might as well have bought any product labelled as pyrex.

This is why I like the concept of an "origin mark" that links to a full record of the whole supply chain for the product. Companies already have that information, exposing it makes buyers able to make [more] rational decisions and then capitalism can actually work to improve products.

That said, using the same trademark for different products in this way should invalidate the trademark (maybe UK TMA1994 S3 can be used in this way??).

What a bunch of borons

Okay... PYREX is borosilicate, pyrex is soda-glass. What about Pyrex? (Where only the first letter is capitalized.)

I won't lie. This is shitty marketing.

Im kind of sure making difference between "PYREX" and "pyrex" is illegal here.

Are these new python package managers?

I refuse to enter into joinder with this discussion, but for the record:

The all-caps name, PYREX, is the de jure, natural bakeware, created of the land (borosilicate). It has inherent, unalienable rights to withstand thermal shock. It is a true vessel.

The lowercase name, Pyrex, is the corporate fiction, the STRAWMAN created under the maritime law of commerce. It is a mere vessel in name only, subject to the whims and defects of its corporate creators. By purchasing it, you are unknowingly consenting to be governed by their rules of catastrophic failure.

Do not be deceived by their fraudulent conveyance. I do not consent to being a party to this contract. I am a free man, traveling upon the land with my original, common-law PYREX.

“World Kitchen in 2000, recognized that the cookware didn't need to be quite as strong, and — to make it accessible to the average customer — it needed to be more affordable.”

Some pretty strong bullshit vibes from this section. Feels a lot more like they decided to make the product worse because they knew the brand name would be enough. I doubt price is a significant factor compared to durability for the average home cook.

Funny to me because just last week I week I wanted to buy a glass jug, and as a natural born procrastinator I just had to google products from Pyrex. Apparently the European products are still made of borosilicate glass in France. In the end I bought one from Anchor Hocking because it has markings etched in and a few people complain their Pyrex markings disappear. I did buy some dishes from Pyrex and they say borosilicate glass on the packaging (made in France).

Essentially PYREX got enshittified into pyrex.