Metal roofs are known for their durability and longevity, and thus may take a number of years for their material to break down and age. The rustic look of tin roofs has long been an attractive feature on homes, barns and sheds. You can achieve this look by rushing the rust process in a matter of hours or days, instead of waiting for nature to do it over the span of years.
Combine soap and water in a bucket. Wearing your rubber gloves, add dish detergent to a bucket of water, following the directions on the soap container for the correct ratio of soap to water.
Scrub the surface of the metal. Dip the steel wool into the soapy water to scrub and clean the oil coating from the metal roof. This oil coating is invisible and put in place to prevent rusting.
Mix 1 part salt to 10 parts water in a Hudson sprayer. Spray the mix evenly over the metal surface. The saltwater will corrode the metal to different degrees depending on how long you leave it on the surface.
Let the metal sit. Once the tin roof has corroded to a point where it looks older--a process that can range from a few hours to a few days--wash the saltwater from the metal surface with the sponge and soapy water.
Seal the metal roof. Spray with anti-rust product or clear spray paint to stop any further rusting.