Cooking with Glass

Detail from ad for Pyrex ovenware, 1916. Pyrex products were the first glass dishes that could be safely used in an oven. Courtesy of Corning Incorporated, Archives.

In 1911 no one cooked with glass, and the prospect of putting a dish in the oven was astounding and even frightening. Household glass was fragile. Mothers taught their daughters not to put glass on top of the stove or in the oven, lest it explode into fast-moving, sharp-edged fragments. People traditionally baked in pans made from cast iron, enameled metal, or ceramics.

That year, in the city of Corning in upstate New York, gossip started buzzing about a major local employer. Corning Glass Works was America’s leading specialty glassmaker, producing components for electric lightbulbs and railway signal lamps. Rumor had it that the company wanted to move into the kitchen.

Corning’s new dishware venture was based on a high-tech glass called borosilicate, first developed in Germany. The company already used a borosilicate glass called Nonex in its signaling lamps, which tolerated the hot flame from the lamp as well as subzero mountain winters. But Corning’s success was a mixed blessing: Nonex signalware almost never shattered, and so the railroads stopped buying replacements in bulk. Corning needed new applications for the glass that was called too good to be true.

Corning’s specialty glassware was the product of skilled artisans who blew or pressed the hot glass into shape by hand. The company needed a product for them to make when the business of lightbulbs and signalware waned. Sales of such household gifts as cookware peaked with June weddings and the Christmas season, and home glassware might just keep the town’s glass artisans fully employed.  

When the cookware idea leaked out, the invention bug spread throughout the town. Nonex railroad glass provided inspiration for Edith Hoare, the daughter of a local cut-glass entrepreneur, and William A. Young, a glassworks employee. The two converted railroad-glass roundels into stovetop utensils and fried up some griddlecakes. The flapjacks came out delicious and the glassware unscathed. Cooking with glass might not be such a crazy idea after all. 

William Churchill, the scientist in charge of Corning’s new venture, was energized by the enthusiasm and gave top priority to kitchen glassware. But making glass dishes proved more challenging than anticipated. Corning chemists discovered that acids from food gradually ate through Nonex glass, releasing lead. In 1913 Corning hired physicist Jesse Littleton to help develop a lead-free borosilicate glass.

In July, Littleton’s wife provided a design breakthrough. Becky Littleton was disappointed with her new clay casserole dish, which broke in the oven. She asked Jesse for help, and he brought home the sawed-off bottoms of some Nonex battery jars. Becky baked a sponge cake in one of them and was delighted by the results and by how easily the dessert slipped out of the pan. Back at the labs, scientists marveled at the cake, declaring it “very well cooked” and “a remarkably uniform shade of brown all over.” Becky used makeshift Nonex pans to cook french fries, steaks, custards, and cocoa.

These kitchen capers helped Churchill think outside the research laboratory box. Acknowledging that cooks had something to offer scientists, he asked professional home economists and celebrity chefs for help. Mildred Maddocks tried out glass bakeware in her test kitchen at the Good Housekeeping Institute, and gave it a thumbs-up. Sarah Tyson Rorer, a best-selling author and founder of the Philadelphia Cooking School, ran tests on ovenware; a Corning memo later noted that company scientists sat “on needles and pins waiting for her report.” They were elated when she praised a baked Alaska made in glass.  

Glass oven dishes were a perfect fit for the age of scientific management, when studies of workers helped factories reach peak performance. “Efficiency” was the watchword, and it spread from factories and offices to the household. Home economists like Maddocks believed that a kitchen could run like a well-oiled machine, providing it was equipped with better-designed appliances and utensils.

To this end Corning chemist Eugene Sullivan began to supervise bread baking at his home. He photographed the loaves to document the speed and volume of their rise. In the physics lab Jesse Littleton oven-boiled water in glass and metal pans to determine which material was more energy efficient. The decisive test entailed a hybrid pan that was part metal and part glass. The cake came out half-baked and sticky against the metal surface and nicely cooked where exposed to the glass.

Churchill seized on these themes as he prepared ovenware for market. In late 1914 or early 1915 Corning finally developed a lead-free borosilicate formula, G 702 EJ. The first dish made was a pie plate, and Churchill suggested the trade name Py-Right or Pie Rite. But in fall 1915 he changed the name to Pyrex to rhyme with Nonex.

The Pyrex brand made its national advertising debut in Good Housekeeping and National Geographic. The new glassware would eradicate the “drudgery of scouring and scrubbing, the fruitless and endless effort to clean things” that resisted “all cleaning!” By 1916 ads featured the first Pyrex cover girl, Catherine Huber, a glassworks secretary, looking through a clear pie plate. This modern working woman assured consumers that Pyrex Ovenware would save “time, labor, fuel.”

The glass that helped railroad engineers find their way was given new life as the glass that saved energy in the home. But in 1998 Corning sold off this business to focus on fiber optics and touch-screen technology. The glassworks that once turned railway roundels into Pyrex pans had become a major player in the global electronics industry. In the United States, Corning’s Pyrex products are now found only in labware, while Pyrex kitchenware is made with a tempered soda-lime glass. Only in Europe are Pyrex pieces still made from borosilicate glass.

Regina Lee Blaszczyk, Ph.D., is a historian at the University of Delaware. She is the author of seven books on the history of innovation, including The Color Revolution, which was funded by an Edelstein Fellowship from CHF’s Beckman Center. Learn more about her work at imaginingconsumers.com.

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