CorningWare cookware was introduced in 1958. Originally, it was made from a material known as pyroceram, which was a mixture of glass and ceramic. In the late 1990s, CorningWare was sold to World Kitchen, which started to make the cookware only out of ceramic. Recently, World Kitchen began to make CorningWare out of the original pyroceram material again. CorningWare is safe to use so long as the manufacturer's instructions are followed.
Pyroceram vs. Ceramic
Pyroceram is able to withstand the heat of the stovetop and the heat of the broiler. It is not recommended that you use ceramic CorningWare dishes under the broil or on the stove, as they will break.
There is a risk of thermal shock when using ceramic CorningWare. To avoid breakage, do not exposure your cookware to sharp changes in temperature, such as placing a hot dish in cold water or putting a dish right from the refrigerator into a hot oven.
Ceramic is Breakable
CorningWare cookware should be handled with care to prevent it from breaking. If it is dropped, it may break and cause harm. However, if situations where breakage can occur are avoided, the cookware is safe to use.
Do Not Use Cracked CorningWare
CorningWare dishes that are chipped or cracked are unsafe to use as they may crack even further, or break potentially causing harm.
Do Not Heat Empty
Never place an empty CorningWare dish in the oven or microwave, as it may overheat and break.
Pyrex E-Mail Scare
In late 2009, an email was circulated claiming that a Pyrex dish, which is owned by the same company as CorningWare, exploded in someone's oven and that this problem was quite common. The website Snopes.com disproved significant portions of the email and further pointed out that all glass is subject to breaking.