What is the difference between PYREX and pyrex?

Introduction:
You may have noticed glasses marked “PYREX” and others labeled “pyrex” in your kitchen. They look the same, but don’t let the name fool you. The difference between PYREX (uppercase) and pyrex (lowercase) is not limited to aesthetics: it is about the chemistry, safety and heat resistance of each type of glass. Let’s break them down in a simple and accessible way, both for amateur cooks and for the curious.

Ingredients:

1 part on the history of glass manufacturing

1 part on the knowledge of glass composition

Part 1 on Consumer Safety Awareness

A pinch of culinary curiosity

Start with a little history: Originally developed by Corning Inc. in 1915, PYREX (in uppercase) was made of borosilicate glass, a heat-resistant material that was ideal for use in the lab and kitchen.