PSA: Removing Cosmoline (Video)

We have a bit of a departure from normal content today – I needed to clean up a really greasy C96 Mauser, and figured it might be useful for some folks to see the process. Cosmoline is great stuff for protecting guns from rusting in storage, but it can be a rear bear to remove. This particular C96 seems have been dunked in the stuff, so I decided to try boiling it in water to melt the cosmoline rather than clean it all with rags and Q-tips. I should note, though, that you don’t want to do this with wooden parts – I left the grips off to clean separately.


  1. Perhaps you’ve mentioned it,I don’t have sound on this pc, but I’ve used a large ultrasonic cleaner on IMA USA Gahendra parts and that worked great.

  2. I’ve had great results with soaking medium and smaller sized parts in mineral spirits. You can also use a capped off section of 3″ or 4″ PVC as a dipping tank for barrels and assemblies (works quite well with Mosin Nagants). However it is critically important to follow that up with proper detail cleaning and oiling or it will flash rust quickly.

  3. one thing I noticed is the thermometer was resting on the foil and not necessarily water temp which may explain the need to turn up the heat. I also wonder, would actual boiling water with bubbles agitate within the parts and clear them better?

    I have no old pistols or any cosmo’ed parts to test, but I was thinking an old thrift-store turkey fryer or a big old stock pot, hanging the big parts with a coat hanger wire and the smaller stuff in a wire basket.

  4. Found a poly pan about 48″ at Lowes or Home Depot. Add about a 1/2 gal. of mineral spirits and allow parts to soak. Usually comes right off with tooth brush or stiff bristle brush. For stocks, Easy-off oven spray and a brush. Rinse with water hose and let dry overnight.

  5. Living out here in the VALLEY OF THE SUN I find that nature is the best answer to Cosmoline. I wait for a day when the temperature is over 110 degrees and place the parts to be cleaned on a piece of 6″PVC tubing that has both ends capped, I saw this tube lengthwise with a band saw so I have 2 “C” shaped sections.

    On the PVC tube I attach a piece of wire mesh Hardware cloth and place the part/parts to be degreased.

    I place the tube and the parts on the ground on my patio. The location is in an ares where the sun will shine on the part for most of the time. Now just allow MOTHER NATURE do her work. The part will be heated by solar heat, the cosmol.ine which has a high paraffin content will soften and run down into the PVC trap. On a day where the sun is bright and the temperature in over 100 degrees F I have used a infrared temperature probe and measure the part temperature at over 195 degrees F.

    Most Cosmolines will flow at less than this temperature.

    Remember that when the process is finished, the part will be dangerous to touch with your bare hands.

    I find that it takes about 5 to 7 hours of sunlight to remove the GUNK from an ENFIELD or BREN gun parts set.

    Normally when the part comes has the gunk removed, I wind it still has a light oil on the surface. I remove this with BRAKE CLEANER.

  6. could you not use a barbecue with a grate,get the right temp and allow it to drip down into the fat tray?? just a thought.

  7. Heat the parts as you did, rinse in a tub of gasoline, blow out with an air gun, rinse parts in diesel and reassemble. Quick and thorough!

  8. Where did you find a C96 still coated in cosmoline? I’ve been looking for one of those for a while and I’d love to find one in that condition. Great video, Ian. The hot water method has always worked well for me too.

    • That C96 was reimported from China, so it was put into cosmoline storage there at some point, not in Germany. The finish is pretty good, but it has some mismatched parts and very little rifling left.

    • “Where did you find a C96 still coated in cosmoline?”

      My thought exactly!

      I haven’t seen any quantity of those since the last batch of Chinese ones.

  9. Come to think of it, all the efficient and successful methods for removing cosmoline have a couple of things in common — use of controlled heating and light solvents. Regardless of methodology, be aware of potential health and fire hazards, and always try to use a method that is environmentally sound. If non-environmentally friendly solvents are used, proper disposal to compensate for this is key. There is absolutely no sense in unnecessarily exposing yourself or your surroundings to toxic chemicals — the chemical and consumer industries at large do enough already without our help!

    • Yep – a big reason I decided to use just soap and water was to avoid any toxic chemicals (aside from the cosmoline itself, which will probably give you a dozen different kinds of cancer).

      • Cosmoline is actually pretty non-toxic by chemical composition, since even to this day it is still a traditional paraffin wax-based grease with few, if any, of the modern chemical additives that tend to cause problems. This goes for Cosmoline from any generally-available approved source, military or civilian grade — American, British, Canadian, Chinese, German, Russian, East European, etc. If you check the well-established Material Safety Data Sheets or their equivalent pertaining to Cosmoline, you will find that known carcinogens are definitely not part of the list. The furthest the MSDS will go is to advise that excessive prolonged exposure to Cosmoline can cause eye irritation and de-fatting of the skin ( loss of natural fatty tissues in the skin ) ; they also state quite specifically that prolonged breathing of Cosmoline vapors ( which would occur mostly in high-heat situations — take note ) in excess of the Threshold Limit Value or TLV can cause headache, dizziness or nausea. For those who are not sure what the TLV for any material or chemical is, it is defined as the allowable concentration of that material or chemical in which one may work over the very long term ( as in a working lifetime ) while being exposed for at least 8 hours a day or 40 hours a week. The TLV for Cosmoline and its components such as Aliphatic Petroleum Solvents, Hexylene Glycol, Metyl Salicylate, Minetral Oils and Petroleum Hydrocarbons is relatively high. For more information, please refer to

        Suffice to say, very few, if any, of us are exposed to Cosmoline on that scale. Even firearms factory workers are seldom subject to this level of exposure. And this is assuming that one is unprotected from direct contact with the material or chemical in question, i.e., no gloves, sealed goggles or respiratory protection / ventilation.

  10. My grandfather served in the US Army in the early 50’s. When they were issued their Garands he told me they removed them from the stock and dipped them in a 55 gallon drum of boiling water to remove the cosmoline, so I suppose that’s the time tested way of doing it.

    • Yep. Dad was a ordinance company commander in Vietnam. So I checked with him what their process was, and it was boiling water. I’ve had no issues with a simple teapot.

  11. I’ve used a handheld steamer to clean up a milsurp rifle (I think it was a K31, it was years ago). Disassembled and steamed the parts over a big plastic tub to catch the drippings. Worked pretty good, and it was pretty easy to direct the heat where needed. Dried and light oil, and good to go.

  12. I am not a big fan of a lot of chemical cleaners or taking hours to clean anything.

    By far the quickest removal is a heat gun. I purchased a heat gun from Grainger and once disassembled I hang my parts up on metal clothes hangers with newspaper below to catch the drippings. Then just start from top to bottom with the heat gun and within minutes almost all of the cosmoline is gone (of course this is done outside). Simple, easy and cheap (after the initial heat gun purchase).

  13. I have battled this many times and tried every home grown method known to man. The secret chemical I employ after years of trial and error is WD40… you will be amazed at how it melts away cosmoline.

  14. A good tip from a UK book on shotgun action disassembly and cleaning was to use bird feathers for cleaning out holes, especially threaded ones.

    They’re much less likely to get stuck than Q tips, and they don’t tend to leave fibres behind.

    • Keith, that’s a great tip, assuming someone isn’t having us on ( which I don’t think they are ). Many thanks!

  15. Like Stephen King, I prefer to use plain WD40 ; other similar light non-toxic solvents such as CRC, LPS-1, Gunk and PB ( Power Blaster ) also work quite well, and you don’t need to resort to heating the parts in question.

  16. The stove top method is VERY BAD!!! Do not use!!! Boil the water separately and then put the parts in. The stove element can get hot enough to remove the temper of the steel if left directly on it. You could ruin the gun if the water boils off and you don’t notice. Boil the water first then pour it onto the parts.

  17. Confession. I used the dishwasher method on a Yugo SKS that was thick with cosmolene. I took apart the rifle and put all the parts including the wood in the dishwasher. The wood looked horrible and I figured I would have to get a synthetic stock anyhow.

    It worked beyond my wildest dreams. I had planned on opening it up before the heat/drying cycle but missed my mark. Everything was bone dry when I opened the door. I do not know how long it was on the drying cycle before I opened the door.

    1. the wood was almost white and fairly dry. Fortunately it had not cracked and I was able to set it out in the sun to dry, sand it, stain and oil it. Looks great now.

    2. All the metal parts were dry and I noticed some surface rust. I cleaned and oiled all the metal parts inside and out immediately. I believe some call this “flash rust.”

    3. I put the rifle together and it works great.

    I checked the interior of the dishwasher and saw no evidence of oil residue. Just to be safe I ran an empty load full cycle with soap to be on the safe side.

    I am not recommending this method, just adding my experience to the list of methods above. And before you ask, no, my wife still does not know about the dishwasher gun cleaning method to this day. 🙂

Leave a Reply

Your email address will not be published.