Cosmoline

Cosmoline is the genericized trademark for a generic class of rust inhibitors, typically conforming to United States Military Standard MIL-C-11796C Class 3, that are a brown colored wax-like mass; have a slight fluorescence; and have a petroleum-like odor and taste (as detected when working with it).

Chemically, cosmoline is a mixture of oily and waxy long-chain, non-polar hydrocarbons. It is always brown in color, but can differ in viscosity and shear strength. Cosmoline melts at 113–125 °F (45–52 °C) and has a flash point of 365 °F (185 °C).

Its most common use is in the storage and preservation of some firearms, hand tools, machine tools and their tooling, and marine equipment. Entire vehicles can be preserved with cosmoline.

Cosmoline is also frequently applied to automotive disc brake rotors at the factory, to prevent corrosion inside the box before the rotor is placed into service on a vehicle. It is easily removed by spraying brake cleaner on the braking surfaces of the rotor.

During World War II, U.S. 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. Cosmoline was also used to coat weapons, including entire tanks, for long sea voyages, as it prevented rust even in salty conditions.

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". Despite this, most servicemen found Cosmoline bothersome to remove; many felt that Cosmoline was not only for preserving the weapon and preventing rust but also for making soldiers' lives miserable.

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