If the logo is in upper case lettering, PYREX, it's most likely made of borosilicate, and thus safer. The lowercase lettering is most likely made of soda-lime glass, so take extra care after any high-heat cooking.
Here's where the branding comes in. All-caps PYREX, which is sold and made in France, is still made of borosilicate glass. But any Pyrex that's all lowercase — a recent change in branding — is soda-lime glass, which isn't designed to withstand drastic temperature changes.
Patterned Pyrex—such as the 1956 Pink Daisy or the 1983 Colonial Mist colorways—tend to be valuable as a collector's item. Other popular patterns include the 1957 Butterprint, which features an Amish couple and their crops, and has been valued at a few hundred dollars.
You'll now find cooking products labeled PYREX in Europe, Africa, and the Middle East, where they are still made with borosilicate glass. The label pyrex stayed stateside, and in the rest of North America, South America, and Asia, and the company that makes them no longer uses borosilicate glass.
The Bottom Line
pyrex: Lowercase indication of containers that should not be heated in the oven or microwave. These are most likely made of soda-lime glass. PYREX: Uppercase label on cookware that is made of borosilicate glass and can be heated in a microwave or oven.
The secret is simple—check the logo. If the brand name is in all capital letters, it's vintage Pyrex. If it's all lowercase, it's modern.
If the logo is in upper case lettering, PYREX, it's most likely made of borosilicate, and thus safer. The lowercase lettering is most likely made of soda-lime glass, so take extra care after any high-heat cooking.
What Makes Pyrex Special. "Pyrex continues to hold its value because most of us associate it with memories of family and holiday gatherings and memories from their childhood," Wright says. "The vintage designs and patterns of Pyrex evoke a nostalgia, which adds to its value for collectors.
This change was justified by stating that soda–lime glass has higher mechanical strength than borosilicate—making it more resistant to physical damage when dropped, which is believed to be the most common cause of breakage in glass bakeware. The glass is also cheaper to produce and more environmentally friendly.
If it's all caps “PYREX,” it's vintage, made of borosilicate. If it's lower case “pyrex,” it's new, and it's soda lime. (In Europe, Pyrex is still made of borosilicate. So these recommendations only apply to Pyrex in the United States.)
A highly-coveted pattern, the Atomic Eyes Chip and Dip is the holy grail for some Pyrex collectors. Released in the 1950s, some of the bowls feature a Pyrex stamp while others don't.
Because borosilicate is the most durable when it comes to withstanding temperature changes, it is generally considered the safest choice for glass bakeware.
Wright notes that Amish Butterprint, Pink Gooseberry, Snowflake Blue, Crazy Daisy and Friendship are also considered valuable in the Pyrex community.
Knowing how to tell if Pyrex is vintage is an important skill. Start by looking for the Pyrex identification mark or logo. If it's all caps (PYREX), you likely have a vintage piece on your hands Then look at the pattern and shape to see if they match up with designs from decades past.
If the logo on your utensil is lettered “PYREX”, it is most likely a product of borosilicate and thus safer. If it is lettered “pyrex" it is most likely made from soda-lime glass so be cautious if you're doing any cooking over high heat. Healthy food hacks What's the Difference Between Pecorino and Parmigiano Cheese?
It's tempered, meaning it's been heated and cooled in a manner that makes it more durable under future temperature fluctuations. It's less likely to break under an impact, and when it does, tempered glass breaks into diamond-like cubes instead of long, pointy shards, so it's a little safer to deal with.
According to the FTC, during the pandemic, Pyrex measuring cups sold on Amazon.com were advertised as made in the United States. In reality, some glass measuring cups were imported from China.
So, why did Pyrex make the change all those years ago? Two primary causes: increased air pollution regulations and a focus on reducing energy consumption. Soda lime glass is better for the environment, requires less energy to produce, and is more easily recyclable—making it the preferable choice.
FYI: Don't put your vintage Pyrex in the dishwasher; its shiny finish will be destroyed. DWD is hard to rehab, although you can rub some coconut oil on a piece to simulate its former sheen. Other damage may look bad, but is actually quite reversible.
In 1915, the company launched its first Pyrex line (Pyrex combined "pie" and "Nonex") with 12 pieces, including pie plates and a loaf pan. The 8-ounce liquid measuring cup came out 10 years later; early versions had a closed, D-shaped handle and tick marks made out of molded glass.
The best way is to look at the bottom of the product. My vintage Pyrex, which is at least 40 years old, and definitely boro-silicate, reads “Not For Lab Or Stovetop Use - Corning N.Y. - U.S.A. - 516 - PYREX.” Newer products made of soda-lime glass do not read Corning N.Y., nor are they made by Corning.
they both withstand temp. up to 450 deg. borosilicate was stronger but to expensive to continue using it. there is no differance in anchor or pyrex they are exactly the same glass soda lime glass.
During testing, soda lime glass shattered at lower temperatures than “more expensive” borosilicate Pyrex® bakeware, the report continued. It turns out that the iconic glass bakeware produced in America today is of soda lime, while the European-made products Consumer Reports tested were borosilicate.