Cosmoline

A brown, wax-like petroleum-based corrosion inhibitor often used to preserve firearms for long term storage. The original Cosmoline was an ointment and was used for many different cosmetic and medical purposes. Cosmoline became widely known when it received a government specification as a rust preventive and began its use by the military to protect various equipment from rust and corrosion. Cosmoline could be found on military equipment in the Spanish–American War, World War I, World War II, and the Korean and Vietnam Wars.