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manufactured c. 1980, featuring graduations in both metric and U.S. Customary systems]] Pyrex ( trademarked as PYREX) is a brand introduced by Corning Inc. in 1908 for a line of clear, low-thermal-expansion borosilicate glass used for laboratory glassware and kitchenware. It was later expanded to include clear and opal ware products made of soda-lime glass. Corning no longer manufactures or markets consumer glass kitchenware and bakeware. Corning Consumer Products Company, which was spun off from Corning Inc. in 1998 and renamed World Kitchen, LLC in 2000, continues to license the pyrex (all lower case) brand for their tempered soda-lime glass line of kitchenware products sold for the consumer market in the United States, South America, and Asia. In the regions of Europe, Africa, and the Middle East the PYREX (all upper case) brand is licensed by International Cookware for use on their borosilicate glass products. The brand name has also been used for non-glass kitchen utensils and cookware in various regions for several decades.


Borosilicate glass was first made by German chemist and glass technologist Otto Schott, founder of Schott AG in 1893, 22 years before Corning produced the Pyrex brand. Schott AG sold the product under the name "Duran". In 1908, Eugene Sullivan, director of research at Corning Glass Works, developed Nonex, a borosilicate low-expansion glass, to reduce breakage in shock-resistant lantern globes and battery jars. Sullivan had learned about Schott's borosilicate glass as a doctoral student in Leipzig, Germany. Jesse Littleton of Corning discovered the cooking potential of borosilicate glass by giving his wife a casserole dish made from a cut-down Nonex battery jar. Corning removed the lead from Nonex and developed it as a consumer product. Corning Pyrex Bakeware, Carroll M. Gantz, Design Chronicles: Significant Mass-produced Designs of the 20th Century, Schiffer Publications, Ltd. 2005 Pyrex made its public debut in 1915 during World War I, positioned as an American-produced alternative to Duran. A Corning executive gave the following account of the etymology of the name "Pyrex": In the late 1930s and 1940s, Corning also introduced other products under the Pyrex brand, including opaque tempered soda-lime glass for bowls and bakeware, and a line of Pyrex Flameware for stovetop use; this borosilicate glass had a bluish tint caused by the addition of alumino-sulfate. In 1958 an internal design department was started by John B. Ward. He redesigned the Pyrex ovenware and Flameware. Over the years, designers such as Penny Sparke, Betty Baugh, Smart Design, TEAMS Design, and others have contributed to the design of the line. Corning divested its consumer products division in 1998, forming the company World Kitchen, LLC. Corning discontinued its production of Pyrex products, but still licensed the Pyrex brand name to other companies, including World Kitchen and Newell Cookware Europe.{{cite web |url=http://www.pyrexware.com/thetruthaboutpyrex/manu.htm |title=Manufacturing History |publisher=Pyrex Products |accessdate=5 June 2015|archiveurl=https://web.archive.org/web/20111002090834/http://www.pyrexware.com/thetruthaboutpyrex/manu.htm|archivedate=2 October 2011}} France-based cookware maker Arc International acquired Newell's European business in early 2006 and currently owns rights to the brand in Europe, the Middle East and Africa.


Older clear-glass Pyrex manufactured by Corning, Arc International's Pyrex products, and Pyrex laboratory glassware is made of borosilicate glass. According to the National Institute of Standards and Technology, borosilicate Pyrex is composed of (as percentage of weight): 4.0% boron, 54.0% oxygen, 2.8% sodium, 1.1% aluminum, 37.7% silicon, and 0.3% potassium. According to glass supplier Pulles and Hannique, borosilicate Pyrex is made of Corning 7740 glass and is equivalent in formulation to Schott Glass 8330 glass sold under the "Duran" brand name. The composition of both Corning 7740 and Schott 8330 is given as 80.6% SiO2, 12.6% B2O3, 4.2% Na2O, 2.2% Al2O3, 0.1% CaO, 0.1% Cl, 0.05% MgO, and 0.04% Fe2O3, Beginning in the 1980's, production of Pyrex glass cookware manufactured by Corning (and later World Kitchen, after the consumer division was spun off and renamed) was shifted to tempered soda-lime glass, like their opal bakeware. This change was justified by stating that soda-lime glass has higher mechanical strength than borosilicatemaking it more resistant to physical damage when dropped, which is believed to be the most common cause of breakage in glass bakeware. Also, it is cheaper to produce and more environmentally friendly. However, unlike borosilicate, its thermal shock resistance is lower, leading to the potential increase in breakage from heat stress if used contrary to recommendations. European Pyrex is still made from borosilicate. Consumer Reports Breaks A Lot Of Glass Investigating Shattering Pyrex Bakeware, The Consumerist The differences between Pyrex-branded glass products has also led to urban legends and the concern of safety issuesin 2008, the Consumer Product Safety Commission reported it had received 66 complaints by users reporting that their Pyrex glassware had shattered over the prior ten years yet concluded that Pyrex glass bakeware does not present a safety concern. The consumer affairs magazine Consumer Reports investigated the issue and released test results, in January 2011, confirming that borosilicate glass bakeware was less susceptible to thermal shock breakage than tempered soda lime bakeware. However, they admitted their testing conditions were “contrary to instructions” provided by the manufacturer. STATS analyzed the data available and found that the most common way that users were injured by glassware was via mechanical breakage, being hit or dropped, and that "the change to soda lime represents a greater net safety benefit."

Use in telescopes

Because of its low expansion characteristics, Pyrex borosilicate glass is often the material of choice for reflective optics in astronomy applications. In 1932, George Ellery Hale approached Corning with the challenge of fabricating the telescope mirror for the California Institute of Technology's Palomar Observatory project. A previous effort to fabricate the optic from fused quartz had failed, the cast blank having voids. The mirror was cast by Corning during 1934–1936 out of borosilicate glass. After a year of cooling, during which it was almost lost to a flood, the blank was completed in 1935. The first blank now resides in the Corning Museum of Glass.


Note Bibliography
  • Gantz, Carroll, (2001). DESIGN CHRONICLES: Significant Mass-produced Products of the 20th Century, Schiffer Publishing,

External links

"green air" © 2007 - Ingo Malchow, Webdesign Neustrelitz
This article based upon the http://en.wikipedia.org/wiki/Pyrex, the free encyclopaedia Wikipedia and is licensed under the GNU Free Documentation License.
Further informations available on the list of authors and history: http://en.wikipedia.org/w/index.php?title=Pyrex&action=history
presented by: Ingo Malchow, Mirower Bogen 22, 17235 Neustrelitz, Germany