Creation
The material that has the qualities CorningWare is noted for was discovered by accident, according to Kitchen Classics. Pyroceram, a glass-ceramic material that could endure quick fluctuations between hot and cold temperatures without breaking, was discovered by S. Donald Stookey, a Corning Glass Works research scientist, when a furnace malfunctioned, producing extremely high heat yet the material didn't melt. Stookey also dropped the material, Kitchen Classics notes, and discovered Pyroceram didn't easily break.
Stovetop
Whether CorningWare can be used on a stovetop depends upon its age. Vintage Blue Cornflower CorningWare was intended to go on stovetops, Your Cookware Helper notes. Newer CorningWare, manufactured from the year 2000 onward, by World Kitchen LLC, is made from stoneware and cannot go on stovetops or endure quick fluctuations in temperatures. Markings on the bakeware and its packaging indicate that it is not stovetop safe. However, World Kitchen LLC recently introduced a four-piece, Pyroceram Blue Cornflower Casserole Set under its Pyrex division that withstands temperature fluctuations as well as the original and can be used directly on stovetops.
Increasing Value
Because they were nearly ubiquitous in homes during a 30-year period, vintage CorningWare casserole dishes are abundant and are found at thrift stores, yard sales and online auction and vintage sites. The original CorningWare Blue Cornflower bakeware, although still easily found, is beginning to gain value, according to Your Cookware Helper.
Stoneware
World Kitchen LLC switched to stoneware to manufacture CorningWare to appeal to the color and design esthetics of modern consumers, according to World Kitchen LLC's CorningWare. Modern consumers also become less interested in the ability of CorningWare products to withstand temperate fluctuations with the development of the home microwave.