Ceramic bowls double as bakeware for mini-casseroles, pot pies, hot dips and other dishes as long as they're oven-safe. If not, you're left with damage to the ceramic's glaze, or worse -- for example, an oven coated in your spinach and goat cheese casserole and littered with the ruins of your bowl.
Why can some ceramic bowls stand up to the oven's heat while others shatter? Because the word "_ceramic_" is much broader than dinnerware marketing would have you believe. A ceramic bowl is any item made with clay and hardened by fire -- including bone china, porcelain, stoneware and earthenware -- and any of these can be finished with a glaze that's either oven-safe or not.
The composition of and firing process used for bone china, a mix of clay and bone ash, and earthenware, a combination of clay and sand, means both are rarely oven-safe. But the makeup of and manufacturing process used for porcelain, made of kaolin clay, and stoneware, a mix of of durable light clays, often result in ovenproof bowls and dishes.
Although porcelain and stoneware ceramics may be oven-safe, the finish of the bowl is the deciding factor. Some decorative glazes include toxic lead or cadmium, which, when exposed to oven temperatures, soak into foods. Other glazes don't create a waterproof seal, leaving the porous clay beneath more sensitive to temperature changes as it absorbs and releases moisture.
Investigating Your Bowl
Finding out what type of ceramic bowl you have is pretty easy if you bought the bowl or know the manufacturer, but figuring out what type of glaze was used is often difficult or impossible. For this reason, use manufacturer guidelines to determine if your specific bowl is oven-safe.
- Look at the bottom of the bowl. Ovenproof dinnerware pieces have notations such as "oven safe" or pictures of ovens on the bottoms. If you see wavy lines and a temperature below 300 degrees Fahrenheit, the bowl can be kept warm in a low-temperature oven, but should not be used for baking food.
- Check the care guide that came with your bowl or set. It will note if the piece is oven-safe and, if so, how to use it in the oven.
- Check the manufacturer's website if you lost your use and care guide. Care and use instructions can be found on the product page or the company's FAQ page.
- Be cautious with antiques. Anything made prior to 1970 should not be used in an oven, even if the bottom of the bowl states that it's oven-safe. Before 1970, manufacturers often used radioactive and other harmful ingredients in the glazes, and these can contaminate food when exposed to heat.
Using Oven-Safe Bowls
Ovenproof ceramic bowls are more finicky than baking sheets or casserole dishes. Most manufacturers indicate 350 degrees Fahrenheit as the maximum cooking temperature, but you also have to take care when preheating the oven and handling the bowl.
- Preheat your oven carefully. When an oven preheats, it uses a higher-than-set temperature to reach the desired cooking temperature quickly. Because this affects the temperature of the racks and walls, which may be hotter than the air in the oven, some ceramic bowl manufacturers state that you need to heat your oven to 225 for 10 minutes before setting the oven to the desired temperature and letting the preheating finish.
- Don't turn on your broiler. Ceramics cannot handle direct heat. Using a broiler or placing the bowl on the stovetop can cause it to explode.
- Make sure the bowl is at room temperature before putting it in the oven. Ceramics can be damaged by sudden temperature changes, such as going straight from the fridge to a preheated oven.
- Be careful when removing the bowl from the oven. Hot ceramics, no matter how durable, may crack or explode if they're placed on or exposed to a wet or cold surface.