About Madhav:A hot top is located on the top of a steel mold or ingot, and it traps impurities that rise out of steel as it cools and takes shape in the mold. During the steel making process, when molten steel has been sufficiently heated, it is poured into an ingot mold. While the steel cools, any impurities it traps will rise to the top of the mold. A cast iron device called a hot top is used to collect these impurities. In order to protect the hot top from damage, the inside of the hot top is lined with refractory materials. Prior to the late 1970s, asbestos was used as an ideal refractory material because of its low cost and ability to withstand high temperatures. At Bethlehem Steel, hot tops were lined with either brick and asbestos-containing mortar or asbestos insulating boards. Exposure to asbestos can cause mesothelioma, lung cancer and other asbestos-related diseases.