Why Does Steel Rust?

Water and air don't harm most metals. But if they touch steel it rusts. Rust is the result of a chemical reaction (oxidation) between steel and oxygen. Water speeds the process. Oxygen from the air dissolves in moisture on the surface of the steel, then rust starts to form. Once it starts, it continues. Untreated steel surfaces must be kept absolutely dry to prevent rust. Stainless steel resists rust because two other metals, chrome and nickel, are alloyed in it. These do not rust. That is why so many kitchen utensils are made from stainless steel. To keep steel from rusting, we have to make sure water and air can't reach it. We can do that by painting the steel or by rubbing it with grease or oil. Or we can put on a thin coat of some metal that won't rust . That's called plating.