Static Weight Loads

Glass-ceramic cooktops are designed to support the weight loads typically experienced by a cooktop during normal operation without breaking. Manufacturers test the strength of their cooktops and generally suggest that the appliances can support a weight load of up to 50 pounds, well above the weight of most normally loaded cooking containers. However, subjecting the cooktop to weight loads beyond normal cooking loads, such as by standing on the cooktop or using it as a storage space, is not recommended.

Impact Resistance

Underwriters Laboratories conducts impact tests to determine whether appliances, including glass-ceramic cooktops, can withstand potential impact-producing accidents without breaking. Cooktops are subjected to impacts from a 1.18-pound steel ball dropped from 20.25 inches above the surface of the cooking element and a 3.96-pound, flat-bottomed weight dropped from 6 inches above the surface. Cooktops that are said to have passed the UL tests have withstood these impacts without breaking.

Durability and Thermal Shock

Conventional tempered glass is not suited to use in cooktops because glass can lose it temper when it is repeatedly heated to high temperatures. Glass that loses its temper is more likely to break when subjected to impact or thermal stress. Glass-ceramic material, however, does not lose its temper and will maintain its strength indefinitely. Glass ceramics are also much more resistant than conventional glass to breakage caused by heating followed by rapid cooling.

Scratches

Glass-ceramic cooktops are susceptible to scratches caused by abrasive materials, and sliding heavy cooking containers across the cooktop is more likely to cause surface scratches than cracks or breakage. Glass containers are not recommended for use on ceramic cooktops for this reason, and porcelain containers should have a smooth surface to avoid scratches. Cast-iron pans are also not recommended.