What is Pyrex and How Does It Differ From Glass?
Pyrex is a brand of kitchenware that was first introduced to the American public by Corning Incorporated in 1915 during World War I. This line of clear, low-thermal-expansion borosilicate glass was intended to be used for laboratory glassware and kitchenware.
These days, Corning no longer manufactures or markets the Pyrex brand of borosilicate glass kitchenware and bakeware in the US. However, the Pyrex products are still manufactured under license by many different companies including World Kitchen LLC – which branched off from Corning in 1998. World Kitchen licensed the brand to create its own line of kitchenware products which were made out of clear tempered soda-lime glass instead of the usual borosilicate glass product. In Europe and the UK, the brand is used for products created by Arc International Cookware.
The Pyrex name was probably an arbitrary word which was created in 1915 as a trademark name for all of the products that were manufactured by Corning Glass Works. There are some theories that the name is a portmanteau of the Greek word ‘pry’ and the Latin word ‘rex’, but this is not a popular opinion and the brand name of Pyrex was more than likely a made-up name for this brand of excellent glassware for kitchen use.
In the late 1930s and 1940s, Corning glass works also introduced many other products under the brand name, including opaque tempered soda-lime glassware bowls and bakeware, as well as a line of Pyrex Flameware that could be used on the stovetop without damage. The Borosilicate glass had a unique blue tint to it that was caused by the addition of alumino-sulphate to the chemicals used to create these products. Pyrex was redesigned in 1958 by the leader of the internal design department, John B Ward. He changed the way that the ovenware and Flameware products were made. Since then, many other designers have contributed to the way that Pyrex products look and function.
The older versions of Pyrex’s clear glass – which was manufactured by Corning before 1998 – was made out of borosilicate glass and, according to the National Institute of Standards and Technology, borosilicate Pyrex is made of up 14 per cent boron, 51 per cent oxygen, three per cent sodium, one per cent aluminium, 38 per cent silicon and less than one per cent potassium. According to the glass supplier for the company, borosilicate Pyrex glass is made of Corning 7740 glass and is the equivalent to Schott Glass 8830 and 7740.
Pyrex glass cookware products which are manufactured by World Kitchen LLC are all made out of tempered soda-lime glass instead of borosilicate. World Kitchen made this change because the soda-lime glass was much more inexpensive to produce – it is now one of the most common forms of glassware used for baking. It has also been said that soda-lime glass has a higher mechanical strength than borosilicate, which makes it more resistant to breakage if dropped.
Due to its low expansion characteristics, Pyrex borosilicate glass is also often used as the main material of choice for reflective optics in astronomy applications. The 200-inch telescope mirror that is located at the California Institute of Technology’s Palomar Observatory was cast by Corning between 1934 and 1936, using the same type of borosilicate glass that was used in Pyrex products.
Pyrex is a heat-resistant form of glass which is typically used for cooking and laboratory applications. This article looks at the history of this curious material, and the ways in which it differs from traditional glass.
Processing your request, Please wait....
