Pyrex

Pyrex is a brand name for glassware, introduced by Corning Incorporated in 1915. Originally, Pyrex was made from thermal shock resistant borosilicate glass. more...

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Since 1998, when Corning spun off its kitchenware division as World Kitchen, Pyrex branded kitchen glassware has been made of soda-lime glass. However, Pyrex brand laboratory glassware is still made of borosilicate glass.

Etymology

A Corning executive gave the following account of the etymology of the Pyrex brand name:

Composition

According to the National Institute of Standards and Technology, Pyrex is made of 4% boron, 54% oxygen, 3% sodium, 1% aluminum, 38% silicon, and less than 1% potassium. Though borosilicates had been produced before the Pyrex brand, the name Pyrex is widely used as a genericized trademark for the material. Corning spun off its cookware and bakeware division in 1998 as World Kitchen but retained the Pyrex brand name, licensing it to World Kitchen and other companies that produce Pyrex-branded cookware (e.g. Newell Rubbermaid's Newell Cookware Europe).

Pyrex kitchen products produced by World Kitchen are no longer made from borosilicate glass, but from soda-lime glass. Their packaging indicates that they must never be used over a flame, on stove tops, under a broiler, or in a toaster oven. Pyrex kitchen products in Europe made and sold by a subsidiary of ARC International tableware company are still made from borosilicate glass.

The brand in Europe, the Middle East and Africa is currently owned by ARC International who acquired the European business in early 2006 from Newell Rubbermaid who in turn had acquired it from Corning in the 1990s.

Usage in telescopes

The California Institute of Technology's 200-inch telescope mirror at Palomar Observatory was cast by Corning during 1934–1936 out of borosilicate glass. In 1934, George Ellery Hale approached Corning with the problem of casting the enormous mirror after spending a million dollars attempting, and failing, to cast the mirror out of ordinary glass. Pyrex was chosen as it undergoes much less thermal expansion than conventional glass, which resulted in fewer problems with distortion and focussing in telescopes. On its second attempt, Corning succeeded in casting a mirror of the requisite purity and smoothness. The observatory to house the mirror was completed in 1936 and the mirror itself transported via train from New York City to Pasadena, California, where it was ground and polished into the requisite parabola over the next 11 years.

Read more at Wikipedia.org