Iron ore
In cast iron sulfur promotes the formation of white iron. As little as 0.5% can counteract the effects of slow cooling and a high silicon content . White cast iron is more brittle, but also harder. It is generally avoided, because it is difficult to work, except in China where high sulfur cast iron, some as high as 0.57%, made with coal and coke, was used to make bells and chimes . According to , good foundry iron should have less than 0.15% sulfur. In the rest of the world a high sulfur cast iron can be used for making castings, but will make poor wrought iron.
Cast-iron cookware
A proper cast iron seasoning protects the cookware from rusting, provides a non-stick surface for cooking, and reduces food interaction with the iron of the pan. However, exposure to acidic foods such as tomatoes removes the seasoning, and the cookware must be re-seasoned again. Enamel-coated cast-iron pans do not need seasoning, as the enamel coating prevents rust in most instances. It is recommended to maintain the seasoning frequently to keep the food from sticking to the iron.