Cosmoline

A brown, wax-like petroleum-based corrosion inhibitor often used to preserve firearms for long term storage. Cosmoline is petroleum-based rust and corrosion-inhibiting grease. The consistency of cosmoline varies widely but is mostly found as grease or wax.

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.

firearm preservation

Once cosmoline has been exposed to air for a few years, it will solidify and become a wax consistency.

Cosmoline can create a dangerous situation with your firearm. Primarily when found in the bore and fire control area. If planning to shoot a firearm that was stored in Cosmoline , leaving cosmoline in the bore can ruin your firearm or, worse yet, cause injury to the shooter. It should be treated as a bore obstruction and removed prior to firing. Cosmoline found in the chamber area can cause failures to extract.

If you plan to fire the gun then you absolutely need to remove all of the Cosmoline. If the gun will spend the rest of its life in storage, it might be better to leave it on.

Removal tools and aids

• Acetone
• kerosene
• good soap like Simply Green
• cloth, rags, gun cleaning tips cloth or cotton based

When trying to remove the Cosmoline keep in mind that harsh chemical solvents that could strip paint, finishes, or other aesthetic/functional coatings from the gun’s surface. If you can remove the gun stock from the barrel and metal parts it would help avoid damage to the stock.

A cold gun is more difficult to clean. You can use a space heater or hair dryer to warm up the gun and thus make the Cosmoline runny.