Rust is the product of corrosion, rust will flake off and leave pits in the surface of a material that is corroding. The amount of water involved in the corrosion process determines the color of the ensuing rust, according to the sources at the University of Hawaii. Rust can vary in color from yellow to orange-brown to black.
There are several factors that contribute to the acceleration of the corrosion process. Rust and corrosion in general occur more rapidly in wet environments than dry environments because of the high moisture presence. According to the University of Hawaii, a high salt presence promotes rusting. Materials rust more quickly where melting salts are used on the roads. Materials are also more likely to rust near the moist, salty air of the oceans. The Checklist for Corrosion Control claims that residual stress from the fabrication of iron or steel, iron and steel's compatibility with other materials and temperature can also encourage corrosion.
According to the Checklist for Corrosion Control, corrosion reduces plant efficiency and increases running costs. Corroding steel costs the United States nearly 3 percent of the country's GDP (gross domestic product) annually, according to the American Galvanizer's Association. This figure comes out to several billion dollars spent each year on preventing or repairing corrosion damage.
Galvanizing a material involves coating it with a layer of zinc. Zinc is an element that naturally features the ability to discourage the process of corrosion. There are a few methods to galvanize a metal. The "hot-dip" galvanizing process involves submerging a material such as iron or steel into a tub of molten zinc. Placing an iron or steel object into a vacuum filled with zinc particles and then heating it is called, "sherardizing," according to the U.S. General Services Administration.
Even in the presence of moisture, iron and steel are both very durable materials that can hold up for several generations in extremely corroding conditions. However, galvanizing a metal such as steel can make it last for well over a hundred years, according to the U.S. General Services Administration.