The original Pyrex logo, introduced by Corning Glass Works in 1915, featured the word PYREX in all-caps, bold, serif lettering.
Will usually just say 'pyrex' in lowercase on the label. All glass Pyrex glassware in the past 30 years made in America is made with soda-lime glass. Their spin-off bakeware (using borosilicate) under the 'pyrex' name is still made in France. It's best to check the label or read the online blurb when buying.
Both trademarks were historically used interchangeably in the marketing of kitchenware products made up of both borosilicate and soda-lime glass. However, now Corning has licensed out the use of their PYREX (upper case lettering) and pyrex (lower case lettering) logos to other companies.
Yes, there are two distinct variations of Pyrex. The difference depends on the capitalization of the logo and where the product was manufactured. They use different materials and handle temperature changes differently:
Pyrex officially transitioned its brand logo from the all-uppercase "PYREX" to the lowercase "pyrex" in the mid-to-late 1970s. The change was a marketing rebrand by Corning, but it is also widely used by collectors to help distinguish older, vintage bakeware from modern replacements.
I contacted Pyrex to ask if there's an easy way to tell what material your Pyrex dish is made from, and the company had a simple answer: Look at the logo. 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.
Old Pyrex (vintage) is primarily made of borosilicate glass, which is highly resistant to extreme temperature shifts. New Pyrex is made of soda-lime glass. While new soda-lime glass is highly resistant to dropping, it is more likely to shatter from thermal shock than older borosilicate glass.
Pyrex manufacturer Corning transitioned away from borosilicate glass in the United States starting in the 1950s—and officially finalized the shift across all consumer lines when the brand was sold in 1998—for three main reasons:
The "good" Pyrex is vintage glassware featuring the uppercase PYREX logo. Made from borosilicate glass, it can handle extreme temperature changes (thermal shock). Modern glassware has a lowercase pyrex logo. Made of tempered soda-lime glass, it is more prone to shattering from sudden temperature shifts.
The absolute rarest and most valuable vintage Pyrex is the "Lucky in Love" Cinderella Casserole Dish. Featuring a white base with green clovers and pink hearts, this rare promotional piece was produced in 1959 but never widely released.
The uppercase PYREX logo (with sharp, capital letters) is generally considered the "good" Pyrex. This vintage glassware is made of borosilicate glass, making it highly durable and resistant to extreme temperature changes.
Yes, you can absolutely still buy Pyrex. However, it is important to know that modern US-made Pyrex is made of tempered soda-lime glass, which is durable for baking but slightly less resistant to extreme thermal shock than the original vintage borosilicate glass.
Identifying vintage or collectible Pyrex comes down to checking the stamped logo, examining the shapes, and matching the patterns.
The key difference is the glass formulation and heat resistance. European Pyrex is made of highly durable borosilicate glass (handling extreme temperature shifts without shattering), while American Pyrex is made of tempered soda-lime glass (stronger against dropping, but prone to thermal shock).
Authentic Pyrex pieces can often be identified by their back stamps, which were used between 1915 and 1965, or by unique characteristics like yellowish or blue-tinted glass. To preserve vintage Pyrex, wash it by hand, as dishwashers can damage the color, and avoid microwaving pieces with metallic paint.
Jolene Forrester of JoRetro in Havre de Grace, Maryland—who hosts the semi-annual Pyrex & Vintage Fest—says pieces in “pinks and turquoises, which instantly stand out and were produced in more limited quantities,” are especially sought after.
Vintage Pyrex refers to glassware manufactured by Corning Glass Works between the 1940s and 1970s. Authentic pieces feature a distinct, highly durable borosilicate glass.
The most common and popular vintage Pyrex patterns are Butterfly Gold and Spring Blossom Green (often called "Crazy Daisy"). Produced in the 1970s and 1980s, these were mass-marketed and often paired with Corelle dinnerware, making them kitchen staples in millions of homes.
Pyrex manufacturer Corning transitioned away from borosilicate glass in the United States starting in the 1950s—and officially finalized the shift across all consumer lines when the brand was sold in 1998—for three main reasons:
Vintage Pyrex has fans for practical reasons: It's tougher than modern Pyrex. All Pyrex cookware, old and new, is made from tempered glass, which stands up well to high and low temperatures. You can bake casseroles in the oven or pop a meal in the freezer.
Pyrex can last a long time. If you have Pyrex that's still in good condition (i.e., no cracks or chips in the glass), don't throw it away. Give it away or donate it to a thrift shop.
NO - Do not use Pyrex® glassware on the stovetop (open flame, electric burner), under the broiler, in a toaster oven, or on a barbecue grill.
To check if your Pyrex is borosilicate, examine the logo and color. Vintage pieces with an all-caps "PYREX" logo and clear, untinted glass are borosilicate. Modern pieces with a lowercase "pyrex" logo or any glass with a blue/green tint are made of soda-lime glass, which shatters more easily under thermal shock.
Just as before, this feature makes borosilicate glass the ideal material for making sustainable glass bottles. These bottles are long-lasting and don't contain any BPA which could damage your health. Fourth, borosilicate glass is resistant to acid, while soda-lime glass is much less so.