The More You Know: Cosmoline Chemistry

Signaling the arrival of a surplus firearm from a time and world nearly forgotten, the sweet smell of the Cosmoline protective coating invokes a Pavlov-like reaction in even the most novice collector. Sure, the moment can be short lived as you decide on a removal method to get to the gun underneath. But as sticky and obnoxious as that amber colored mixture is, it’s hard not to appreciate its amazing corrosion resistance properties.

But what exactly is Cosmoline? What makes it such a great long-term protective coating? Should I use it on my guns? Do they even make Cosmoline anymore?

Standby. I’ll see what I can do…


Actually, that is just tree sap.

Here’s my standard disclosure: It’s been almost 20 years since I’ve used chemistry in my professional life. Undoubtedly, a chemical engineer or petroleum scientist is going to come along and say “that’s not exactly true”. You’re right; just consider this a “Cosmoline chemistry for trigger-pullers” write up.


In it’s most popular form, Cosmoline has been around for nearly 200 years. However, if you believe unsourced Wikipedia statements, chemically similar substances have been found being used as a preservative in ancient Egyptian pyramid tombs.

For better or worse, the ‘original’ Cosmoline product doesn’t exist anymore. The current exclusive distributor markets a product called “Original Cosmoline” or Rust Veto 342 which is as close to the real thing available. However, it is actually more of a liquid than a gel like the OG coating.

From the Schafco Information Page:

Cosmoline was developed by Houghton International in the late 1800’s as a pharmaceutical product. The original Cosmoline was basically an ointment and was used for many different cosmetic and medical purposes. It was kept in homes to disinfect wounds and was used by veterinarians to treat cuts, abrasions, bruises and sprains. Cosmoline could even be found on the farms where it was used to relieve swelling in cow’s udders.

As industry changed so did Cosmoline. New formulations of Cosmoline were developed to meet the ever growing need. Cosmoline products were available in ranges from a light type fluid to a thick, heavy grease meant for long term protection. Cosmoline’s versatility was unparalleled.

Cosmoline became an everyday name when it received a government specification as a rust preventive and began being used by the military to protect it’s equipment from rust and corrosion. Cosmoline could be found on military equipment in the Spanish-American War, World War I, World War II, the Korean conflict and Vietnam.

In 1958 Schafco Packaging began packaging Cosmoline products into aerosol versions for Houghton International and in 2004 Schafco became the exclusive distributor for the Cosmoline Aerosol line of products.


Rust Veto 342 i.e. “Original Cosmoline” i.e. “Coke Classic”

That’s great and all, but what actually is Cosmoline?

From the Cosmoline Wikipedia Page:

Chemically, cosmoline is a homogeneous 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).

Of course, oily and waxy long-chain non-polar hydrocarbons! Should have known…

Let’s take a look at the chemical composition of wax.

From the Parafin Wax Wikipedia Page:

Hentriacontane, also called untriacontane, is a solid, long-chain alkane hydrocarbon with the structural formula CH3(CH2)29CH3.


Long-chain hydrocarbons like wax are exactly that – long chains of bonded carbon and hydrogen. In the image above, the carbon atoms are represented at the points in the chain. The hydrogen atoms are taken for granted as two bonds off each of the carbon. This coincides with the more than two to one ratio of hydrogen to carbon atoms – 31 carbons and 64 hydrogens (the carbons at the chain ends have three hydrogen bonds).

Who cares? What does this have to do with Cosmoline being awesome?

Long chain hydrocarbons are hydrophobic, meaning they “fear” (repel) water. But their non-polar characteristics give them an added anti corrosive benefit.

Non-Polar Hydrocarbons From ‘What Is Chemistry’:

Because hydrocarbons consist only C-H bonds, which are non-polar. When you look at the table of electronegativity (Pauling scale), you see, that the difference between the electronegativities of carbon and hydrogen is much smaller than that of nitrogen and hydrogen. That is why N-H bonds are considered polar, and C-H bonds are not.

Without getting super-technical, the Pauling Scale gives a electromagnetic charge value to each element. Since the long chain, non-polar hydrocarbons are comprised of only Carbon and Hydrogen , there is no excessive charge differential like “head and tail” polar molecules have. The head of a polar hydrocarbon is a bond with another atom like nitrogen.



Non-Polar solution, Left.  In hydrophobic reaction , Right.

Usually, non polar compounds are not water soluble because they contain neither ionic groups nor polar functional groups that can interact favorably with water molecules. Those compounds are called “hydrophobic” (water fearing), because they escape the contact with water. Hydrocarbons, constituted by carbon and hydrogen only, are examples of such a kind of compounds. When non polar molecules enter aqueous medium, some water-water hydrogen bonds are to be broken to create a cavity for the solute molecule. Each solute molecule is entrapped in a cage, ice-like, structure formed by highly ordered water molecules, held together by hydrogen bonds. The formed complex, with the non polar molecule in the centre encircled by the cage of water molecules, is called “hydrate”.

Water molecules in the cage around the non polar molecule are more ordered than in pure water. In the presence of many hydrocarbon molecules, the same number of ordered cages of water molecules should form, with the consequent large increase in the order of the system, a process naturally unfavorable. To minimize the increase in the order of the system, hydrocarbon molecules, each one encircled by its own cage of water molecules, associate together (hydrophobic interaction). If, for sake of simplicity, only two non polar molecules in aqueous solution are considered, hydrophobic interaction causes the non polar molecules to come together into a single cavity to reduce the unfavorable interaction with water.

To put it simply, polar hydrophobic substances create the opportunity to allow water in and interact with the iron (the gun? and iron alloys to corrode (rust). Non-polar hydrocarbons pull water in out of solution to be encapsulated and away from the iron. No rust!

But what else is in Cosmoline?

From the (current) Cosmoline Manufacterer SafeTy data sheet (MSDS):


Calcium dihydroxide is most likely added in small amounts to clarify the solution and to aid in the water encapsulation process.

2-Methylpentane-2,4-diol is used to lower surface tensions between two liquids (oils/waxes and water, for example):

2-Methyl-2,4-pentanediol exhibits both surfactant and emulsion-stabilizing properties. Its relatively high viscosity and low volatility are advantageous in coatings, cleansers, cosmetics, solvents, and hydraulic fluids.

One major difference between today’s Cosmoline and the original formulations we know and love is that it has a lower melting point. This means removal of Cosmoline with moderate heat is easier, however storage of items in higher heat environments is more challenging.


Is Cosmoline still available and does it still have a place in firearm storage?

Yes and yes. Several formulations are available for retail sale at CosmolineDirect. As far as long-term corrosion protection, follow the preparation and application procedures and your EOTWAWKI guns will be just fine.

That is, unless earth is attacked by aliens who excrete high temperature, high pressure solvents or detergents. In that case our Nagants, and the world as we know it, are toast.

Cosmoline Chemistry – That’s ‘The More You Know’



LE – Science – OSINT.
On a mission to make all of my guns as quiet as possible.
Twitter: @gunboxready
Instagram: @tfb_pete


  • John A. Smith

    Great post!

  • Johnsmyname

    Cool post, thanks.

    FYI for those who don’t know, WD-40 is great for removing the stuff.

    • iksnilol

      ” WD-40 is great”

      Fixed your post.

      • Johnsmyname

        Hah! True, thanks.

      • Wow

        You have WD-40 in Norway and Serbia?

        • iksnilol

          Yeah, There’s WD-40 in Norway and Bosnia. It’s an international product, and a real good one at that.

          • ostiariusalpha

            Unless you try to use it as a lubricant for anything more than mild applications; there’s a reason that it’s nicknamed “Wanton Destruction-40” amongst gunsmiths. The stuff is fantastic for so many things that some people just assume that it can be used in place of industrial lubricants, and then bring in their semi-auto guns with galled internals for repair.

          • TheNotoriousIUD

            Yeah, the WD stands for water displacement.

          • Spencerhut

            Shhhhh . . . I make a lot of money fixing guns people use WD-40 on.

          • Jibber

            I saw a Ruger 10/22 that had been “lubricated” with WD-40. It had hardened to this yellow shellac(sp?) and seized the action solid.

          • Spencerhut

            Yup. Get them all the time. Tighter the fit, the harder they are to get loose.

          • iksnilol

            Dude, that’s an improvement. That’s like bedding, but inside the action. It makes for better accuracy.

          • BraveNewWhirled

            Yep. If it don’t move it lasts longer and never misses.

          • Ryfyle

            I used it more as a lights rust remover when I’m out of transmission fluid. I have lubed Mosin bolts with a scented candle wax before.

          • ostiariusalpha

            Did you play soft, romantic music and have rose-petals scattered on silk sheets while applying the wax? You can’t just jump straight to the wax and handcuffs without establishing the mood first.

          • Phillip Cooper


            You have to use crops and floggers before the wax.

            Geez, some people……

          • iksnilol

            I also primarily use for rust removal… And a guy in Norway did lubricate a rifle with butter.

          • Wow

            Jesi li Srbin, Hrvat ili bošnjački? I figured WD-40 would have been a go in the EU. I assumed they would have banned it for environmental reasons

          • ostiariusalpha

            Why? It’s non-toxic and biodegradable.

          • iksnilol

            Bosanac sam ja.

            I don’t see the environmental problems with WD-40.

          • Wow

            Ti si se borio su Srbi? Ja sam Rus.

          • iksnilol

            Nisam, moj stari se borio protiv Srba.

          • Wow

            To je strašno. Zašto se boriti Srbi? Kakvo je Vaše mišljenje o Kosovo? su Albanci zaista kradu organe? laži?

          • iksnilol

            Zato sto su nas srbi probali istrijebit. Onda je normalno se protiv njihan borit.

            Albanija i Kosovo me ne interesuju, imam dovoljno svoji konflikta da se mjesam u tudze.

          • Phillip Cooper

            Where’s that “English, do you speak it?” meme when I need it?? 🙂

          • iksnilol

            I do speak English, thought it was obvious.

      • phuzz

        If it moves and it shouldn’t, use duct tape.
        If it doesn’t move and it should, use WD-40.

        • iksnilol

          Didn’t work for Simba, buddy.

    • Bigg Bunyon

      So is plain old el-cheapo Mineral Spirits. I like the odorless kind better though as I want my gun safes to have that “Cosmo-essence” aroma.

    • tts

      MEK (Methyl-Ethyl-Ketone) is even better but use (proper) gloves and do it out doors.

      MEK might as well be liquid cancer but its one of the most effective solvents that you can legally and cheaply buy. Does some serious damage to paint and can soften powder coatings too so be careful what you use or splash it on.

      • nova3930

        Only worse than MEK is Methyl-Ethyl-Ketone Peroxide. It’s everything MEK is plus explosive and will eat your skin of and the fumes will burn the eyeballs from your skull…

        • tts

          Might as well use pure DCM (dichloromethane) if you’re looking for something better than MEK and don’t mind the extra toxicity and are willing to buy online or find a chem shop that will sell it to you. And it is indeed extra toxic for anyone planning on using it so read up on its handling and MSDS if you’re going to try it. Works like magic on stripping paint and powder coats too but be as careful with it as you would a loaded gun.

          MEKP is better than MEK as a solvent in general but not really enough to bother tracking a shop down that has it in volume or dealing with the extra toxicity IMO. You can at least just walk into any ACE or homedepot and buy MEK by the gallon or pint without issue so no waiting on a ebay shipper or online store so you can buy more than a ounce or 2.

          I’m sure better stuff out there than DCM or MEKP exists for stripping cosmo or paint but boy things start getting real impractical, expensive, dangerous real quick at that point.

          • derpmaster

            PERC is less toxic than both. You can get high and pass out/get a headache on DCM or MEK. PERC is practically a miracle chemical – it strips grease, removes spots from fabric and carpets, and generally just annihilates any kind of stubborn dirt/stain you encounter.

            Stock up while they still sell it, the red can BrakeKleen brand is basically 99% pure PERC, however I’m sure the enviro-weenies will try and ban it at some point.

          • tts

            I’m actually not that impressed with PERC despite all the good I’ve heard of it. It isn’t bad at all mind you. Many people are perfectly fine with Brakleen when stripping cosmo (or paint) but DCM had it beat hands down and never seemed much better than MEK to me. Almost freakish to watch how quick it works on paint and other things, you’ll think you’re watching a time lapse video.

            And yeah unfortunately people keep not disposing of PERC and other useful chemicals properly so they keep ending up in the water supply or soil which is a real concern in some areas that had factories at one point. Watching kids die from cancer or early on set Parkinson’s is some ugly stuff.

          • ostiariusalpha

            It is banned in Kalifornia.

          • Dougscamo

            What ain’t?….besides liberals….

        • Spencerhut

          Yeah .. . we’ll do that!

        • Rodford Smith

          Just gonna go straight to chlorine trifluoride, the most powerful known fluorinating agent. It will spontaneously ignite on contact with and burn brick, sand, asbestos and rocket technicians. 🙂

        • iksnilol

          I’mma stick to diesel or CLP.

    • Gary Kirk
      • I use that on everything for my bike fleet and more!
        Grease on rotor? Brakleen!
        Cleaning 22/45 barrel? Brakleen!
        Birthday cake too dry? Brakleen!

        • Benji

          Careful! I used to use it all over everything too, then I read a story about some old Harley guy who cleaned a case with Brakleen, dried it off and then tried to weld it. There was still some Brakleen residue there and apparently when it gets REALLY hot Brakleen releases phosgene gas. Poor guy must have huffed like 0.01cc of vaporized Brakleen and how he’s go severe multiple sclerosis like symptoms for life.

          • That’s actually one of the most helpful comments I’ve ever received, thank you!

          • Phillip Cooper

            This is a well-known issue among professional, and informed hobbyist, welders.

      • Jim_Macklin

        CRC 5-56 I’ve still got a gallon of it. Different applications need different lubricants, solvents new stuff is invented all the time.
        Used to have a coupe of cans of RIG.
        Brownell’s has RIG still.

        • tarnishedcopper

          Rig is one of the very best when it comes to preventing rust. In fact I refer to it as modern-day Colmoline.

        • A Curmudgeon

          That 5-56 stuff smells like RAID roach killer to me. My Dad always kept some around but it gave me the willies!

      • Phillip Cooper

        When I acquire a new firearm, this is the first thing I do- glove up and take it outside and run a can of this through all the moving bits. Then liberally apply CLP and see how she works.

        Doing this, I’ve never had a problem with “problem-prone” firearms like my Keltecs, Taurus, et al.

        Why? Shipping grease. It’s not there for running the gun, but protecting it in shipment. Remove the goopy stuff, apply the slippery stuff, and go have fun.

    • Johnsmyname

      Lots of good alternatives mentioned to my WD-40 comment. With that said, the one thing I like about WD-40 is it is relatively safe to yourself and other things like wood/gloss/paint. Many ways to skin the cat though.

      • Gary Kirk

        I prefer not to use wd40 as it can dry into an almost resin like state that can pretty much glue parts together.. Zep 45 is meant to dry and leave a Teflon coating kinda like CLP.. Still don’t use it on my firearms, I have CLP..

        • You might like boeshield, too!

        • Bill

          This, If it forms a gummy residue arid the spray nozzle, it’ll form a gummy residue in a gun. I use it a lot, on things like lawnmowers and cleaning garden tools, but not for life critical things.

      • cargosquid

        Must use Glorious Soviet Vodka! You pour it on rifle. You drink. You pour more on rifle. You drink. You set rifle on fire. You drink. You put rifle out with blood of nazis. You drink.

      • BraveNewWhirled

        Tell me more about the cat-skinning.

        • Phillip Cooper

          I love cats… but I can never eat a whole one.

    • marathag

      Old enough to have used Carbon Tet to remove it, and when that wasn’t around, white gas.

    • Just say’n

      A parts washer works great too. I think Harbor Freight has them, but I use the one at work.

    • Captain Obvious

      Actually boiling water is the best thing to remove cosmoline It’s non toxic and cheap. It melts and washes it right off and drys the metal because of the heat.

      • RMP52

        Agree with the boiling water. Easy, cheap, everyone has it. Strip the gun, put the small parts in a pan boiling water and watch the Cosmoline melt away. Larger parts, such as stock and barrel, make a trough and pour the water over them. Then if you REALLY want things clean, stick it all in the dishwasher with your normal dish soap and run on high temp. This will do a good job of cleaning those old grease soaked stocks too.

        • Capn Jack

          Not to mention your spoke hubcaps.

      • Also extremely safe. I really hate dealing with toxic chemicals.

      • Doom

        even better than boiling water is a quality hair dryer. You dont ruin a pot with cosmoline that way, and it will help push out some of the cosmoline from the stock and nooks and crannies in the wood.

    • VanDiemensLand

      My favourite cologne!

    • carlcasino

      WD-40 is wonderful but never use on Blued Guns unless you are trying to remove the Bluing. I learned the hard way on a Moss that I was going to use as a home defense weapon.

    • GunFarce

      For those ‘wives’ that don’t know, the Household dishwasher is great for removing cosmoline from wooden stocks you may not want to soak with WD-40. It also has the side benefit of the hot water raising any dents in the wood. The stock comes out looking like new. But don’t let her catch you..ha

  • iksnilol

    Sooo… to get more OG cosmoline I need to buy a bunch of stored Mosins and melt it outta them into a vat? How will I protect the Mosins that i extracted the cosmoline from then?

    • Tom of Toms

      Refinish with traditional rust bluing or browning, initiating each layer with the blood of fallen comrades.

      • cargosquid

        Fallen enemies, not comrades.

        • Nashvone

          The Mosin was so good, the enemies would pick them up and shoot them at their fleeing owners.

          • cargosquid

            Of course! Mosin Nagant is God’s weap…I mean, good socialist weapon.

    • ostiariusalpha

      Put them directly into the nearest Mosin security container, aka a trash bin. That will afford them every ounce of protection they merit.

      • Tom of Toms

        What’s that Comrade? You volunteer blood for Comrade Mosin? Bravo, Comrade.

        • Ryfyle

          Reminds me of when my Mosy had a sticky bolt and some rough burrs.

      • cargosquid

        What? Glorious rifle of nazi-killing is glorious! Magnificent rifle that all other rifles admire and envy.

  • Jeff Smith
    • Pete – TFB Writer

      I wanted to use that meme so bad, but it has probably been over done.

      • Jeff Smith

        It’s never going to be not funny to me.

      • Doom

        After reading it was used as a cosmetic and medical product, sure, why not. Even more plausible now. lol.

  • nova3930

    The reason Lenin looks so good in that glass case is they soaked him in cosmoline…

  • Hoplopfheil

    Speaking of cosmoline, I’m on the fence about buying a Yugo SKS. Somebody convince me one way or the other! 🙂

    • ostiariusalpha

      *yelling* DON’T DO IT!!!!!

      Okay, so I have no particular good reason to give for not buying one, but I just thought someone should go through the motions.

      *more yelling*
      5) STRIPPER CLIPS?! LAME!!!!
      9) … ?
      10) PROFIT.

      • Hoplopfheil

        Oh well forget the whole thing. 🙂

        (although the alternative is building a 7.62 AR upper, which has the added benefit of being lots more fun)

        • Nashvone

          Classic Firearms sells them at a reasonable price all the time. I say buy the damn thing and enjoy it. If nothing else, you can get your money back if you sell it. As for what ostiariusalpha said, a Honda Gold Wing is a smoother riding, more reliable motorcycle that gets better gas mileage than a Harley. Which one is going to be a better story to tell your grandkids after you ride it around the country?

          • J.T.

            $430 is a reasonable price now? Damn.

          • Nashvone

            It’s better than Gander Mountain’s $550 to $600.

    • cargosquid

      Depends on the price.

    • VanDiemensLand

      One day when they’re way more expensive you’ll wish you had, plus they’re not cheap because they’re crap, they’re cheap because quantity.

    • iksnilol

      Do it.

      + stripper clips are awesome, you save so much money and time that you’d use messing with mags.

    • Do it. I love mine.

      I’m a collector all Yugo firearms.

  • noob

    Did they coat non-firearms military equipment with it? I wonder what sort of heat source you’d use to safely melt the cosmoline out of spare parts for a tank.

    • Pete – TFB Writer

      Tanks for the long ship voyages. I believe they used high pressure sprayers.

  • uncle fester

    Unexpected and appreciated story. Good job.

  • ljones

    Good old boiling water and Simple Green HD will take off cosmoline like nothing. Just wipe off excess first then use boiling water and Simple Green HD and scrub. The rinse. Metal is oil and grease free. Then spray with gun oil and wipe off excess. Cosmoline gone and metal preserved and ready to shoot.

  • Seth Hill

    Bake the cosmoline out. There are people using trash cans and light bulbs to do it. Down here in the deep south, you can just take the gun apart, and stand them in the sun in the summer.

  • Kent San

    Nice job!!

  • Very fascinating.

    Personally, I was always curious at how safe the stuff was. Seems not too bad.

  • carlcasino

    High heat breaks down so it’s easily removed? As a Global Climate Change skeptic and a silly individual that actually believes the world will be consumed by fire( in a few billion Years) I have faith in Cosmoline doing it’s job in my lifetime.