Cosmoline is the trade name for a generic class of rust preventatives, conforming to MIL-C-11796C Class 3, that are a yellowish, light-amber, or greenish colored ointment-like mass; have a slight fluorescence; and have a petroleum-like odor and taste. Cosmoline is similar to petroleum jelly in properties, appearance, and thickness. It is the purified residue obtained from the distillation of petroleum oils.

Chemically, cosmoline is a Homogeneous mixture of oily and waxy long-chain, non-polar hydrocarbons. It can range in color from white to yellow, and can differ in viscosity and shear strength. Cosmoline melts at 113–125 °F (45–52 °C) and has a flashpoint of 365 °F (185 °C).

Its most common use is in the storage and preservation of firearms. Previously, cosmoline was used to preserve other items. Objects the size of entire vehicles could be preserved for future use with cosmoline.

During World War II, US Coast Artillerymen (serving the huge coastal artillery batteries) were known as "Cosmoliners" because they were tasked with the near constant cosmoline application ("greasing down") of the guns.

During Pacific island campaigns in World War II, the United States Marines sang a song about Cosmoline. Adapting the popular big-band tune "Tangerine," they would sing "Cosmoline...keeps my rifle clean."

Due to its gelatinous nature, Cosmoline can be difficult to remove completely from firearms and, as such, is being extensively replaced with vacuum-pack PET film.

See also

• Rust

External links

• Guide to Cosmoline removal from firearms #2
• Brownells Catalog entry
• Mil-C-11796 Revision C military specification that covers the generic rust preventative known by the tradename "Cosmoline"