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.)
If it's all caps Pyrex, it's vintage, made of borosilicate. If it's lowercase Pyrex, it's new. And it's soda lime.
Pattern. Patterned Pyrex—such as the 1956 Pink Daisy or the 1983 Colonial Mist—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.
Broken or chipped Pyrex should be disposed of carefully in the waste bin.
The brand switched its formula in the 1950s to the soda lime glass, but recently started reintroducing borosilicate glass. Although both glasses are heat-resistant, borosilicate glass does better with extreme temperatures, making the vintage Pyrex pieces highly coveted by collectors.
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.
Pyrex dishes also hide a little secret code: Many contain a three- or four-digit number that corresponds to a specific dish. A series of Mixing Bowls will feature 401 (1.5 pint), 402 (1.5 quart), 403 (2.5 quart), 404 (4 quart). The iconic two-quart green-and-white casserole dish is a 232.
While vintage Pyrex is durable and even safer than newer tempered glass dishes, it's still essential to follow some precautions to ensure safe use. First, always bring your vintage Pyrex to room temperature before placing it in the oven.
Everywhere! Fun, collectible vintage Pyrex is easy to find at almost any antique store, but you'll pay a higher price. Scout thrift stores, Goodwill or garage sales for the best deals. If a piece looks a bit worn, it may still be worth grabbing because you can easily remove scratches from Pyrex.
While some collectors prefer to scour estate sales and antique shops, you can also purchase Pyrex from online sellers. Vintage pieces are listed for up to $15,000 on the reseller site eBay, but the actual price depends on the design and rarity.
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.
If your glassware has a signature or maker's mark, this could indicate a rare or unique item. Check the bottom of the piece for any markings or symbols that may constitute a signature. Many glassware manufacturers, such as Tiffany & Co. and Waterford, are known for producing high-quality and valuable pieces.
People like what they like. For others, it's all about nostalgia. Pyrex released 170 different patterns from 1956 to 1983, each with a whimsical name like Golden Honeysuckle, Lucky in Love, Pineapple Party, Cloverberry, and Angelfish.
What Are the Patterns to Look For? The most sought-after pattern of all time is Lucky In Love. This promotional pattern was released in 1959, and very few pieces remain. The cheerful round casserole dish has green shamrocks and pink hearts and is encircled by blades of green grass.
Vintage Pyrex Stamp and Logo
Flip over your piece and look at it carefully. It will have a stamp that can help you date it: 1940s and 1950s - The oldest Pyrex markings should be on the bottom of glass pieces and feature Pyrex in all capital letters inside a circle with CG for Corning Glassworks.
More than 750 million pieces of CorningWare have been manufactured. In 1998 however, due to slumping sales and retooling of manufacturing plants, Corning sold off the CorningWare and Pyrex lines to World Kitchen, LLC.
“The most rare Pyrex patterns are the promotional Pyrex,” says Lucie Courchesne of LucysMidCentury. Promotional Pyrex patterns were sometimes referred to as “non-standard” and were usually offered for a limited time. The company often marketed them as gifts for holidays.
Corning divested itself of the Corning Consumer Products Company (now known as Corelle Brands) in 1998 and production of consumer Pyrex products went with it. Its previous licensing of the name to Newell Cookware Europe remained in effect.
As Cruz explains, the majority of Pyrex collectors do it for the nostalgia: They grew up with Pyrex pieces and appreciate the reminder of home. Others love the retro style. But no matter what draws you to old-school Pyrex, there's one hard-to-beat benefit to the game: These pieces are forever useful.
Liquid dish soap, Mr. Clean Magic Eraser, Baking Soda, Bar Keeper's Friend, Corningware Cleaner, Oven Cleaner, Dawn Powder Dissolver, Goo-gone, and Scotch-brite pads. I think most Pyrex collectors will agree that aside from dish soap, Mr. Clean Magic Eraser is one of the most useful cleaners for Pyrex!
Pyrex itself does not contain lead, but the paint on older pieces often does. The amounts are small and it would basically be impossible to get “lead poisioning” from drinking from the item.
Unfortunately, if your Pyrex bakeware and containers are no longer usable, they'll need to be disposed of in your landfill bin. This applies to both the old-style borosilicate glass and the more modern tempered glass varieties.
The naming of these new pieces as "Cinderella" likely had much to do with the popularity of the Cinderella story current at the time both in film and on Broadway. Corning marketers also hoped the underlying theme of a coveted glass object would have a subliminal effect on consumers.
The "23" was inspired by Michael Jordan, the greatest basketball player of all time, while "Pyrex" was meant to represent the Tupperware used to cook drugs. Playing basketball and selling drugs, he said, were often thought to be the only ways to make it out of the hood.
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.