How to Tell if Pyrex Is Borosilicate?

Pyrex is a brand name for borosilicate glass, which is a type of firm, heat-resistant glass. It’s often used for cooking and baking because it can withstand high temperatures and won’t shatter like regular glass. If you’re not sure if your Pyrex dish is borosilicate, there are a few ways to check.

How to Tell If Glass is Borosilicate

If you are unsure if a piece of glassware is made from borosilicate, there are a few ways to tell.

  • One way to tell if Pyrex is borosilicate is to look for a stamp on the bottom of the dish.
  • Borosilicate dishes often have a stamp that says “Pyrex” or “Boroclass.
  • It’s also possible to evaluate a dish at home by just observing the color. When you look at the edge of a dish constructed of soda-lime glass, it will have a blueish-green color. You should not detect any color if the glass is borosilicate.
  • Also, look for the “B” symbol at the bottom of the piece. This indicates that the drink contains boron oxide and is borosilicate.
  • Another way to tell if the glass is borosilicate is by its weight. Borosilicate glasses are heavier than regular glasses because of their boron content. Finally, you can usually identify borosilicate glass by its clear, colorless appearance.

If you’re unsure whether a piece of glassware is borosilicate, it’s always best to err on caution and assume it is. This will help ensure that you don’t accidentally damage your glassware by using it in a way that it wasn’t meant to be used (for example, using regular dish soap on borosilicate dishes could cause them to crack).

Pyrex Borosilicate

Pyrex borosilicate is a strong, durable, and heat-resistant material used in various applications. It is made up of boron, oxygen, and silicon atoms, which give it its distinctive properties. German chemist Otto Schott developed this type of glass in the early 20th century.

It was created for use in scientific laboratories, as it could withstand high temperatures and pressures. Today, Pyrex borosilicate is still widely used in labs, but it has also become a popular material for making cookware, bakeware, and even jewelry. In addition, Pyrex borosilicate is prized for its strength and durability.

It can withstand temperatures up to 500 degrees Celsius (932 degrees Fahrenheit), making it ideal for use in ovens and microwaves. Additionally, this type of glass is highly resistant to thermal shock, meaning it won’t break if suddenly exposed to extreme changes in temperature (such as from hot to cold). However, one downside of Pyrex borosilicate is that it can be challenging to work with.

However, experienced artisans and craftsmen have learned how to cut, shape and sand this rigid material into beautiful pieces of art or functional items like cookware.

When Did Pyrex Stop Using Borosilicate?

Borosilicate glass was first created in 1887 by German chemist Otto Schott. It was initially used for scientific applications because of its ability to withstand extreme temperatures and resist chemical corrosion. In the early 20th century, borosilicate glass became famous for household items like cooking pots and bakeware because it was lighter and cheaper than other types of glass.

In 1998, Corning Incorporated (the company that manufactures Pyrex) stopped using borosilicate glass in favor of a less expensive soda-lime silicate glass. This decision was made in response to increased competition from other brands selling similar products made with soda-lime silicate glass at lower prices. While Pyrex products made with soda-lime silicate are not as durable as those made with borosilicate, they are still safe to use for cooking and baking.

Old Pyrex vs. New Pyrex: Which is better?

This is a question that many people have when they are looking to buy new Pyrex cookware. However, there are a few things that you should consider when making your decision.

Here are some differences between each option:

Old Pyrex:

  • It is made of borosilicate glass, known for its durability and resistance to thermal shock. This means it can withstand high temperatures and sudden changes in temperature without breaking.
  • It has a smooth surface that makes it easy to clean.
  • It is oven-safe, microwave-safe, dishwasher-safe and freezer-safe. (You might be interested in Can You Put Pyrex On Stovetop?)

New Pyrex:

  • It has a nonstick surface that makes it easy to clean.
  • It can withstand temperatures up to 450 degrees Fahrenheit (232 degrees Celsius).
  • It can be used in microwaves, but it’s not oven or broiler safe. Both types of glass are safe for use in your kitchen as long as you follow proper care instructions: Wash them by hand with warm water and mild detergent.

Pyrex Collectors Guide

Pyrex first hit the market in 1915 and was an immediate success. These early pieces were made of clear glass and featured simple, solid colors. Pyrex quickly became known for its durability and versatility, as it could be used for cooking and storage.

Over the years, Pyrex has released hundreds of different patterns and designs, making it a favorite among collectors. While some collect all things Pyrex, others focus on specific patterns or colors. No matter what you order, here are a few things to remember when starting or adding to your collection.

First, consider what type of Pyrex you want to collect. Early pieces are often the most valuable, but newer items can be just as lovely (and sometimes more affordable). You might also want to focus on a particular color or pattern that speaks to you.

There are many choices out there – take your time and find something you love! Once you’ve decided what to collect, research to get an idea of values. Check online auction sites and forums dedicated to Pyrex collecting – these can be great resources for finding out what similar items have sold for recently.

Having an idea of values will help you make intelligent decisions when buying pieces for your collection. Finally, take care of your collection once you have it! Store pieces in a cool, dry place away from direct sunlight.

If possible, avoid stacking items on top of each other – this could cause chips or cracks over time. Your Pyrex collection will last for years (or even generations) with care!

Borosilicate Glass Vs. Pyrex

There are many types of glass, but two of the most popular are borosilicate glass and Pyrex. Both have their unique properties and uses. So, which one is right for you?

Borosilicate glass is known for its durability and resistance to thermal shock. In addition, it can withstand sudden temperature changes better than other types of glass. That makes it a good choice for cookware and bakeware used in the oven or on the stovetop.

Pyrex is made from a glass type containing silica and boric oxide. This combination gives it a higher melting point than regular glass. Pyrex is often used for storage containers, baking dishes, and laboratory equipment because it can withstand high temperatures without breaking.

Borosilicate Glass Cookware

Borosilicate glass cookware is a type of glass that is designed for cooking. It is made of borosilicate, a material resistant to heat and chemical damage. Borosilicate cookware is available in various shapes and sizes and can be used for cooking and serving food.

Borosilicate glass cookware has many benefits over other types of cookware. It is non-porous, so it does not absorb flavors or smells from food. Borosilicate glass is also highly resistant to thermal shock, meaning it can withstand sudden changes in temperature without shattering.

This makes it ideal for use in the oven or on the stovetop. Borosilicate glass cookware is also easy to clean and care for. It can be washed by hand or in the dishwasher and does not require special cleaners or treatments.

When properly cared for, borosilicate cookware will last for many years.

Pyrex Borosilicate Vs. Soda Lime

There are two main types of Pyrex – borosilicate and soda lime.

Both have pros and cons, so it’s essential to know the difference before making a purchase.

Borosilicate Pyrex is made with boric oxide, which makes it more heat resistant than soda lime Pyrex.

  • It can also withstand sudden temperature changes better than soda lime, making it ideal for use in the oven or stovetop. However, borosilicate is more expensive and can be harder to find than soda lime.

Soda lime Pyrex is made with sodium carbonate and calcium oxide.

  • It’s less heat resistant than borosilicate but can withstand temperatures up to 350 degrees Fahrenheit. Soda lime is also cheaper and more widely available than borosilicate.

How Do You Know If It’s Borosilicate Glass?

Borosilicate glass is a type of glass that contains boron trioxide, which gives the glass greater strength and heat resistance than traditional soda-lime glass. There are several ways to tell if a piece of glass is made from borosilicate or not. One way to tell is by looking at the weight of the glass.

Borosilicate glasses tend to be heavier than soda-lime glasses of the same size. Another way to tell is by looking at the expansion coefficient of the glass. The expansion coefficient of borosilicate glasses is lower than that of soda-lime glasses, so borosilicate glasses will expand less when heated and contract less when cooled.

You can also test for borosilicate content using a refractometer. To do this, you’ll need to take a sample of the glass and measure its refractive index using a refractometer. The refractive index of borosilicate glasses is higher than that of soda-lime glasses.

If you’re still unsure, you can always contact the manufacturer or supplier of the glass and ask them what type of glass it is.

When Did Pyrex Stop Using Borosilicate Glass?

Pyrex stopped using borosilicate glass in 1998. Instead, the company switched to soda-lime glass, cheaper and easier to produce. While borosilicate glass is more heat-resistant and durable, it’s also more expensive and challenging to work with.

How Do You Tell the Difference Between Old And New Pyrex?

When it comes to Pyrex, there are three main ways to tell the difference between old and new. The first is by looking at the bottom of the dish. If it has a raised design, then it is most likely old.

If the bottom is smooth, then it is probably new. The second way to tell is by looking at the color. New Pyrex is usually clear or white, while old Pyrex often has a blue tint.

The last way to tell the difference is by feeling the weight of the dish. Old Pyrex tends to be heavier than new Pyrex because it was made with thicker glass.

What Does Borosilicate Glass Feel Like?

Borosilicate glass has a smooth, silky feel to it. It’s solid and durable yet lightweight and easy to work with. When heated, it maintains its shape well and doesn’t expand or contract like other types of glass.

This makes it ideal for ovens, cookware, and scientific lab equipment.


You will need to look for a few specific things to tell if your Pyrex is borosilicate. First, check to see if the bottom of the dish has a raised “B” or “BSi” symbol. This indicates that the dish is made of borosilicate glass.

You can also try holding the dish to a light source and looking at it closely. If you see tiny air bubbles throughout the glass, your Pyrex is made of borosilicate. Finally, borosilicate glass is typically heavier than other types of glass, so if you pick up a dish and it feels cumbersome for its size, this is likely another sign that it is made of borosilicate.


How to Tell if Pyrex Is Vintage?

Use the glass markings, stamps, and logos on the pieces themselves to identify when the glass was produced. A glass item’s quality is dependent upon many factors, and age is one of them. There are different methods for testing an item’s age: using the markings on the piece or through testing to determine its boron content, which can then be compared with known data for similar pieces. The two primary types of pyrex are translucent and opaque. Translucent pyrex can be identified by a little T inside a diamond etched onto its base.

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Meet Fuad, the passionate baker behind Bakingbakewaresets Blog. With years of experience, Fuad shares his favorite recipes, baking tips, and recommendations for the best bakeware sets. His goal is to help readers achieve success in their baking endeavors, whether they're beginners or experienced bakers. Outside of baking, Fuad enjoys traveling, trying new cuisines, and spending time outdoors. Join Fuad on his baking journey and get inspired to create delicious treats in your own kitchen.