Cast-iron cookware is prized for its ability to withstand high temperatures, superior heat retention and natural nonstick properties. It can last for generations, so it often has sentimental value. When glass cooktops were introduced for home kitchens in the 1970s, manufacturers discouraged the use of cast-iron cookware on the glass-ceramic surface. But advances in technology and design have altered those recommendations. With extra care, you can use your cast-iron cookware on your glass cooktop.
The greatest danger in using cast-iron cookware on a glass-ceramic surface is breakage. Cast iron is much heavier than aluminum or tempered-glass cookware, and glass cooktops are fragile. An injudicious movement or accidentally setting a pan down too hard on the cooktop can easily break the glass. Replacing the glass is expensive and time-consuming, so it is important to handle your cast iron with special care around your glass cooktop.
Watch for Scratches
Another danger when using cast iron on a glass cooktop is scratching the cooking surface. Scratches are not just unsightly blemishes on the cooktop. They can compromise the integrity of the glass, making it more prone to breaking or cracking. Cast-iron cookware, especially heirloom cast iron, often has a rough surface that can scratch the cooktop if the pan is handled carelessly. Sliding cookware across the cooking surface, whether to move the pan or to agitate the contents, can also cause scratches on the cooktop.
Most modern manufacturers of cast-iron cookware design their products with flat bottoms. Older cast-iron pieces, however, may have a raised ring on the bottom of the pan. These pieces should not be used with glass cooktops, which are designed for use with flat-bottomed pans. The raised-ring design of most heirloom cast iron is one reason that manufacturers do not recommend using cast-iron cookware on their glass cooktops.
When selecting cast-iron cookware for use on your glass cooktop, do not choose items with painted or colored bottoms. According to the Cookware Manufacturers Association, under certain conditions, the paint can melt and fuse itself to the cooktop. This type of damage is not usually covered by the cooktop manufacturer's warranty and can be very expensive to repair.
Make sure that the diameter of your pan is nearly the same diameter as the cooking element. Dr. Leona Hawks of the Utah State University Cooperative Extension states that pans should not extend more than 1 inch beyond the cooking element. Using a pan that is too large can overheat a glass cooktop and cause it to crack or break. Using a pan that is smaller than the heating element wastes energy and presents a burn hazard.
If you choose to use cast-iron cookware on your glass cooktop, take precautions to prevent damage to the cooking surface. Wear padded mitts when handling cast-iron cookware, so that the shock of a burn doesn't cause you to drop your pan. Set pots and pans gently on the cooking surface. Do not slide pans across the cooktop or heating elements. Keep the cooktop and the bottoms of your pans clean. Wipe up spills quickly, especially spills of gritty ingredients like salt.