How This Revolutionary Industrial Glass Made its Way Into Your Kitchen

By Alissa Walker on at

You might not know it by name, but chances are you have a Pyrex dish in your kitchen right now. A fascinating history over at Collectors Weekly traces the ubiquitous supermaterial as part of an exhibition which opened this week at the Corning Museum of Glass.

Pyrex was invented in 1915 after the US railroad industry came to Corning Glass Works asking for help designing new signal lanterns; the existing silicate glass ones had a tendency to shatter due to temperature variations. The scientists proposed using boron in the glass due to its atomic properties: it didn’t have a tendency to expand and contract as much as conventional glass did when heated and cooled. The borosilicate glass was named Nonex or CNX (Corning Non-Expansion), and then Corning eventually began producing domestic cookware under the name Pyrex.

It was such a novel concept to Americans that all the marketing for Pyrex had to introduce the idea of “cooking in glass”.

How This Revolutionary Industrial Glass Made Its Way Into Your Kitchen

Pyrex particularly took off during World Wars I and II due to the need to conserve metal for military operations. It was considered to be a patriotic move to switch from tin baking sheets, for example, to Pyrex. But Pyrex also got a big nod when it was used in an important astronomy application: a mirror for a telescope that was two times bigger than anything else on the planet:

The Pyrex name got a major publicity boost beginning in 1929, when astronomer George Ellery Hale commissioned Corning to produce a 200-inch glass disk (nearly 17 feet) for a huge new telescope in California—twice the diameter of the largest existing telescopic mirror at the time. Manufacturing such disks required specialized materials and extreme precision, for if the glass expanded and contracted unevenly, its imagery would forever be distorted. Corning physicist Dr. George V. McCauley designed a gigantic disk for Hale using the Pyrex borosilicate formula and incorporating a complex honeycomb surface pattern to lighten the object’s weight.

Though an initial attempt at the 200-inch disk failed, McCauley’s team successfully completed the task in December of 1934, after which the disk was gradually cooled for 10 months through a process known as “annealing.” Thousands of people flocked to railway lines as the giant Pyrex shipping crate carrying the lens made its way from New York to California, where it would be carefully ground, polished, and finally installed in 1948.

The entire story will give you new appreciation for the whimsically patterned cookware you see next time you’re at the flea market—or for the utilitarian measuring cup that’s probably already in your kitchen cabinet.

[Collectors Weekly]

Images by Corning Museum of Glass via Collectors Weekly