Pyrex

Pyrex is a brand of heat-resistant glassware that was originally made from borosilicate glass, a material known for its low thermal expansion, making it ideal for kitchen and laboratory use. However, while the trademarked PYREX® brand for laboratory products and older cookware remains borosilicate, the consumer kitchenware brand pyrex in North America has predominantly used tempered soda lime glass since the late 1990s. This change means modern pyrex cookware is less resistant to sudden temperature changes and should not be transferred directly from the freezer to the oven, unlike its vintage counterparts.