Corning Glass Company/Corning Glass Works, Corning, New York (1875-to date). (Now known as Corning Incorporated).
The trademark “Pyrex” was first used c. 1915 for Corning’s borosilicate heat-resistant glassware formula. VERY large quantities of kitchenware, serving bowls, ovenware, measuring pitchers, etc, as well as glass electrical insulators for telephone and power lines were made.
Pyrex ovenware has been a staple in American households for many decades.
Bottles and other types of heat and chemical-resistant laboratory glassware are also found with the “PYREX” name embossed on the bottom. Glass tubing, test tubes, lab bottles, funnels and other miscellaneous laboratory equipment and containers were made in quantity.
Some “Carnival glass” insulators were made, bearing the PYREX / CORNING brand marking. The most common Pyrex insulator (found in clear glass) would probably be the CD 128 style. A search of the internet, such as Google Images pages with “Pyrex insulator” and “CD 128” should bring up examples of that particular shape.
Pictured to the left are PYREX name brand ovenware casserole/mixing bowls. The style or inventory number assigned to this size/type of bowl appears to be “402” as each example has that number embossed on the base, as well as the lettering “TRADE MARK / PYREX / R [in circle] / MADE IN U.S.A. / OVEN WARE”. Each measures about 7 & 1/4th inches in diameter and 3 & 3/4ths inches in height. They probably date from the 1970s or 1980s.
NOTE: In 1998, Corning discontinued the production of their PYREX line of glassware, (concentrating instead on their lines of tech-related products) and the rights to the PYREX brand name was assigned to World Kitchen, LLC. The original formula for the glass was evidently changed, after 1998, to a tempered soda-lime glass.
There have been complaints by consumers that this recently-made glassware (ovenware, etc) has shattered and appears to be inferior to previous standards of durability characteristic of the earlier borosilicate formula.
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For more detailed information on Pyrex glass, check Wikipedia’s webpage here.