How to Remove Cosmoline – Practical Guide

How To Remove Cosmoline
Alfred Mendoza

Those who have dealt with firearms for a long time most certainly have experienced the dilemmas of cosmoline. It’s the mess, gross and slimy petroleum that appears to be wrapped in every surface of firearms.

To help you get rid of this slimy substance, our team spent 48 hours researching the easiest steps in removing cosmoline from your firearms.

Cosmoline is a general term for a group of petroleum-based greases with high viscosity, intrinsic rust and corrosion protection, a waxy brown appearance, and a distinct industrial odor. Originally, it was sold as a home disinfectant and veterinary anti-swelling treatment in the late 1800s. 

The greasy substance is used to prevent their military surplus rifles from rusting. Militaries worldwide immediately embraced cosmoline as a means of chemically embalming small weapons, armored vehicles, and other items for long-term depot or transatlantic transport.

What Is Cosmoline

5 Steps in Removing Cosmoline

1. Gather The Things You’ll Need

The first step you need to do is to gather the things you’ll need for this cosmoline removal. Here are the stuff you’ll need:  

  • Mineral spirits or acetone and kerosene
  • Water and soap
  • Shop rags
  • A toothbrush or a smaller paintbrush. 
  • Q-tips for cleaning the other metal sections of the gun
  • Oven or heat gun 

Avoid using gasoline and harsh chemical solvents as your cleaner because that can strip paint and other coatings from the gun’s surface. A reminder on why you shouldn’t use gasoline to clean a firearm: it’s simply not practicable to clean a firearm, especially in the quantities required to clean a standard C&R pistol.

2. Clean Your Gun To Remove Cosmoline

Next, you need to clean your gun. The cleaning process starts by removing as much of the cosmolines as possible. Try to disassemble your rifle first, then clean its parts by section. 

Apply heat to the gun

To clean your gun, you can apply heat. You can accomplish this by wiping your handgun, placing it in a black trash bag, and leaving it out under the hot sun.

Clean Your Gun To Remove Cosmoline

You can also use another heat source to melt the cosmoline to its liquid condition, such as a heat gun or an oven.  

Cosmoline melts at temperatures ranging from 115 to 125 degrees Fahrenheit. Attempting to remove the rust-preventive after allowing the cosmoline to warm up can result in an oilier finish. 

Apply Chemicals

Mineral spirits are known as a major solvent for removing cosmoline, and you can apply it with a rag. Depending on the container or the size of the firearm, soaking guns in mineral spirits can be done in a huge container.

You have the option to disassemble your firearm before beginning this process or keeping it intact throughout the cleaning process. It depends on the matter of your desire. Most of the cosmoline may be getting rid of after a few baths. You can proceed to the real cleaning whenever you’re satisfied.

3. Use Dish Soap & Hot Water To Remove Excess Cosmoline

These two things will help eliminate the last residues out of your gun. Pour the boiling water into the grease, then repeat the process until your water runs clear and you can handle each part without feeling oily. The more you wash and rinse the rifle, the more creep will appear. 

For the small parts of the weapon, try to soak them first in hot water. At this point, disassembling the gun or sections of it, such as bolt assembly, and being soaked in mineral spirits may be more beneficial.

4. Dry It Out

Of course, after the wash and rinse process of cleaning, the firearm needs to be dry. Wipe off the sections or metal parts of the gun that you disassembled using shop rags. By that, you can also grab the tiny residues that were left in the firearm. 

Another tip for faster drying without any extra work is to place it in a well-ventilated area so that the wind or air can travel smoothly around the area.

Dry It Out

5. Finish It With Lube & Oil

You’ll finally remove the majority of the cosmoline from the gun after hours of scrubbing—but basically, you can’t stop there. For extra protection of the piece, you’ll need to add lubricant and stain (for wood stock), especially to the bolt assembly. 

It’s important to extract as many residues and greases out of the gun as possible to avoid the risk of disassembling the gun in the future to uncover a hidden chunk of the rust-preventive gunk.

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Why You Should Remove It

Oil or grease, residue, and dirt can build up in the barrel and internal parts during shooting sessions. When you shoot, residual fouling builds up in the barrel. If the firearm is left to accumulate for too long, it may clog, resulting in a firing failure or the need for repairs. 

Also, older cosmoline tends to solidify when exposed to air for a long time, making it hard to remove. That’s why it is important to clean and remove it in your rifle to keep your firearm operating at its best performance.


Yes, cosmoline is toxic because it is a petroleum-based grease. All petroleum-based products are chemical mixtures that are highly complex. Despite being virtually entirely made up of hydrocarbons, the composition varies depending on the crude oil source. In general, their toxicity to humans is minimal, although there are exceptions. [1]

Not really. There’s no study that cosmoline has a bad effect on rubber. But there is a kind of cosmoline that is used for vehicles. It is used for undercoating and preventing the damages in a car caused by driving on roads.

Not really. Although most greases will burn, cosmolines are rarely considered a fire threat. The lubricating fluid in most lubricating greases is petroleum-derived minerals. Those materials are classified as combustible rather than flammable. Grease will burn when exposed to temperatures, but it will not catch fire.

So, How Do You Remove Cosmoline?

There are few procedures that you can use to remove and clean cosmoline from your military surplus guns. You can use the oven and even the heat from the sun to melt the cosmos. You can also apply chemicals such as acetone and kerosene. Just avoid gasoline as your cleaning solvent as it’s not advisable to use. 

A kitty litter can also remove cosmo in your guns. You’ll have to put them all together inside a box or small storage, together with the thing you want to cosmo be removed and leave under the sunlight for a few days. In addition, dish soap and water can remove the excess residues in your weapon too. Afterward, you can dry out your gun and finish it with lube.



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