The Discovery of Pyroceram aka Corningware

In my research, I found this interesting excerpt from “The Annual Report of the Board of Regents of The Smithsonian Institute for the Year 1962.” The following is the discover of Pyroceram in S. Donald Stookey’s own words:

“A new world is suddenly unfolding to the startled glass technologist as he gazes into his 6,000-year-old crystal ball. As his eyes gradually adjust to seeing in molecular detail the familiar transparent solid turns out to hold a frozen mass of hidden fairy-tale princesses, powerful sleeping giants and unknown creatures of all kinds, condensed to molecular size and trapped in an unexplored labyrinth; each waiting to be brought to life by the proper magic word.

An Accident Leads To Glass Ceramics

Chance, in the form of a runaway furnace, now took a hand. A plate of photosensitive glass that had been irradiated was accidentally heated to several hundred degrees higher than its usual developing temperature. The plate, which we had expected would melt to a pool of glass, altered instead to a hard, strong crystalline ceramic– the first member of a now rapidly growing family of crystalline ceramics made from glass, the Pyrocerams. This was not an isolated case; my colleagues and I soon found that the principle of nucleation-controlled crystallization of glass can be very broadly applied. Plate 3 shows three stages in the process of nucleation and crystallization in a glass ceramic.

Meanwhile, a search for materials suitable as radomes for supersonic missiles made for the Navy by the Johns Hopkins Applied Physics Laboratory, singled out some of the new glass-ceramics as being almost unique in meeting the requirements of strength resistance to supersonic rain erosion and thermal shock, and radar-transmitting properties. This led to pilot production and testing of radomes for the Terrier and Tartar missiles now standard on the missile ships for the Navy. Use of new glass manufacturing methods, developed in continuous-tank production of optical glass, resulted in radomes that can be mass-produced uniformly and not individually tailored to meet the boresight tolerances required for accurate aiming of the missile. One of these is illustrated in plate 1. More and more varieties of radomes, ultrahigh-frequency windows, and antennas are being made of glass-ceramics.

The strength, chemical resistance, and thermal shock resistance of some of the low-expansion glass-ceramics suggest that they could be valuable for domestic use as well as for defense; and we developed the now-popular heat resistant ceramic utensils for cooking and serving food. A new high-strength glass-ceramic tableware will soon be commercial.

Still newer glass-ceramics are now in the development stage, each tailor-made for a special area of use. One, having exceptionally high dielectric constant, is being developed for capacitors; another, containing crystals of an electronic semiconducting oxide, will be used for high-temperature resistors. And a third variety of glass-ceramics, highly crystalline, contains crystals so small that they do not scatter light, and this glass-ceramic is as transparent as glass. The crystals are beta-eucryptite, a strange mineral which shirnks, instead of expanding as do most crystals, when heated. The resultant glass-ceramic has a negative coefficient of expansion.”