Sheet iron was used for roofing as early as the 1790s. When rolling mills started mass-producing it in the 1800s, it became a popular low-cost, lightweight, low-maintenance, and mostly important, fire resistant roofing material across the country. Coating steel to prevent rust and deterioration is not a new idea. The process of galvanizing steel – to coat steel with zinc to resist corrosion-- was developed in France in 1837 and was in use in the US by the 1850s. Galvanized steel roofing is still popular and is available in a variety of thicknesses. Thickness can range from 30 gauge (thin) to 18 gauge (thick). Zinc plating is most common, but aluminum and aluminum-zinc alloy plated materials are also available. A coating of lead and tin alloy gives us terne metal. One of the newest tern metal products uses a base of stainless steel for a high-priced, high quality weather resistant roof. Early tin-plated roofs were often painted dark red or reddish brown to prevent rusting. Today’s painted steel roofs come in a huge color range. Factory-finished metal roof stand up to harsh weather for many years, and a special resin finish prevents fading.