What are the numbers on the bottom of Pyrex?

Author: Bryon Friesen  |  Last update: Saturday, June 20, 2026

Each Pyrex piece is assigned a model number, though some of the earliest sets of color ware pieces do not have them. Model numbers are typically found on the bottom of your glassware, though sometimes they are located elsewhere—look for them above the trademark on your dishes, and around handles and edges of lids.

What do numbers on the bottom of Pyrex mean?

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.

How can I tell how old my Pyrex is?

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.

How to tell if Pyrex is valuable?

We're all thinking the same thing: Is the Pyrex sitting in my basement worth any money? A few clues in the product's design key us into the possible value: the condition and colorway. You'll want to try and find vintage dishes made between 1915 and 1970, as experts tell TODAY that these are the priciest of all.

What is the most sought after Pyrex?

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.

Vintage Glassware!

What is the holy grail of Pyrex?

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.

Which Pyrex is vintage?

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.)

How do I know what Pyrex I have?

Each Pyrex piece is assigned a model number, though some of the earliest sets of color ware pieces do not have them. Model numbers are typically found on the bottom of your glassware, though sometimes they are located elsewhere—look for them above the trademark on your dishes, and around handles and edges of lids.

Is there really a difference between Pyrex and Pyrex?

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.

What are the hard to find Pyrex patterns?

Other patterns considered rare would be the Turquoise Diamond, Pink Daisy, Snowflake, Black (or Atomic) Starburst and New Dots, to name a few. The most popular shapes are by far the mixing bowls which can simply be round or have a spout on one end and a handle on the other, known as Cinderella mixing bowls.

When should you throw away Pyrex?

Baking glassware such as Pyrex dishes in usable condition should be donated to local thrift stores or otherwise reused. If unusable they should be thrown away in the trash. They should not be added to curbside recycling. They are made of a different material than glass bottles and jars.

What is the oldest piece of Pyrex?

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.

How can you tell how old a glass bowl is?

A simple way is to compare any glass you think is antique with a more modern glass item. Antique glass is usually heavier. Other indicators to look out for are: The patina: older glass tends to show signs of use and passing time - so see if there are any small flakes, scratches and chips, or missing gilt.

What do numbers on bottom of glass mean?

In most cases, one- or two-digit numbers are actually mold numbers that indicate the specific bottle mold or section in an automatic bottle machine. If numerous molds were identical, each one received its own number. Base numbers also indicate bottle styles or shapes, manufacturing dates, or factory location codes.

How can you tell if clear Pyrex is vintage?

It's lasted for decades. 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.

What does Pyrex 23 mean?

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.

How to tell if Pyrex is safe?

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.

Is anchor hocking the same as Pyrex?

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.

Does Pyrex break if dropped?

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.

What is the difference between old Pyrex and new Pyrex?

In the U.S., modern Pyrex cookware is made from a type of tempered glass called soda lime glass, which isn't nearly as durable as the glass used in older pieces called borosilicate. Incredibly tough, borosilicate has one especially notable superpower: the ability to endure sudden shifts in temperature.

Why is CorningWare not made anymore?

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.

Why is Pyrex so collectible?

It's utilitarian glassware with unique patterns and an inherently American identity — an identity that has become far more complicated than a simple piece of cookware. Millennial and Gen Z home cooks are scouring estate sales, eBay, Craigslist, Goodwill, and other thrift stores for a Pyrex score.

Why is Pyrex not as good anymore?

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.

Can you put Pyrex glass in the microwave?

The USDA Food Safety and Inspection Service has deemed Pyrex as microwave safe. There are some things you need to know though! Pyrex is made of either borosilicate or soda lime glass and is heat resistant up to 425 degrees Fahrenheit, making it a good option for microwaving.

What is anchor hocking glass made of?

More than 100 years later, the brand has evolved from glass bakeware into other glass products that include food storage, serveware, drinkware, mixing bowls, and more. Anchor Hocking glass bakeware is made with tempered soda-lime glass, giving it durability and heat resistance.

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