Lori Funston, age 13, Etobicoke, Ontario, Canada, for her question.

WHAT MAKES RUST?

Rust is that reddish-brown substance that you find on the surface of iron or steel after the metal has been exposed to damp weather without first receiving proper protection.

Rust is actually formed by the union of the oxygen in the air with the iron through a process called oxidation. Moisture is the most important agent that brings about the chemical change.

Rust can weaken the metal as well as corrode the surface. Long periods of exposure can actually cause holes to form in sheet metal.

Tools may be protected against possible rust by coating them with a thin layer of oil. Heavy grease and sprayed-on plastic coatings can also prevent rust on some equipment.