Pyrex: Brand name for cookware brand. 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.
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.
They switched formulas after Corning spun off its consumer products division in the late 1980s to Corelle Brands. The change was sold and justified by the company as making the glass safer, but it was seen by consumers as a cost cutting decision by management to make the new company more profitable.
If the logo is in upper case lettering it is the safer Borosilicate Glass now made in France or it is vintage Corning made Borosilicate Glass.
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. HOWEVER.
The next time you go to cook dinner in a Pyrex pan, take a look at the labeling. Cookware with lowercase logos are usually made of soda-lime glass and should not be heated up in the oven or microwave to minimize risk of them breaking.
As long as you follow the same guidelines above, vintage Pyrex is A-OK to go in the oven and can be used in oven temperatures up to 425ºF (and skip the broiler). There is one caveat to using your vintage Pyrex, though: Do not use any vintage dishes that are chipped or cracked—in the oven or otherwise.
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.
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.
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.
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.
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.
This can be tested by heating a small piece of glass and observing how much it expands. Weight: Borosilicate glass is generally denser and heavier than soda-lime glass. Clarity: Borosilicate glass is known for its clarity, while soda-lime glass can have a slight green tint.
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.
Corning later licensed the use of the names PYREX and pyrex to two different companies who now produce the glass cookware. You'll now find cooking products labeled PYREX in Europe, Africa, and the Middle East, where they are still made with borosilicate glass.
Decorative patterns are also key to determining the glassware's value. Lucky in Love, a sweet pink and green design, is prized for its rarity and promotional production. Wright notes that Amish Butterprint, Pink Gooseberry, Snowflake Blue, Crazy Daisy and Friendship are also considered valuable in the Pyrex community.
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.
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.
CorningWare and Pyrex, both manufactured by the same company, are two frontrunners when it comes to bakeware, but if you have limited space or are shopping on a budget, it can be hard to choose between the two. When choosing a casserole dish, the top pick is CorningWare, for its flexibility, versatility and safety.
Some of the most elusive Pyrex pieces go for hundreds of dollars, and there are even anecdotes of collectors bidding thousands for rare pieces. A rare Lucky in Love Pyrex casserole dish from 1959—what might have been only a test pattern, made of shamrocks and hearts—sold for $5,994 in a 2017 Goodwill auction.
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. You still have to be careful.
Broken or chipped Pyrex should be disposed of carefully in the waste bin.
DO NOT use or repair any glassware that is chipped, cracked or severely scratched. DO NOT drop or hit glassware against a hard object or strike utensils against it. Pyrex® Glassware can be used for cooking, baking, warming and reheating food in microwave ovens and preheated conventional or convection ovens.
Allow Pyrex to Come to Room Temperature Before Changing Its Temperature. This goes for transferring Pyrex from the fridge or freezer to the oven, or vice versa. Allow Pyrex to come to room temperature before immersing in water or placing in the freezer, refrigerator, microwave or pre-heated oven.