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Removing rust from deactivated ordnance with Oxalic Acid

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    Removing rust from deactivated ordnance with Oxalic Acid

    I am sure many of you know about this already, but just in case you don't, using Oxalic Acid is a great way to remove rust from deactivated metal ordnance and munitions items. This is especially true if you don't want to harm the original paint.

    Oxalic Acid can be easily purchased in a crystallized powder form on Ebay. It is a natural occurring organic substance found in many plants and vegetables, but is toxic in the form I am referring to. Be sure to follow all precautions if you use it.

    I had this British WWII sign that I'd been wanting to remove the rust from for a while, so while I was at it, I threw a couple deactivated ordnance items in the bath with it just to see how things turned out.

    Picture 1 - Before
    Picture 2 - In the Oxalic Acid/water bath after 10 minutes
    Picture 3 - After 15 minutes
    Picture 3 - Results after 60 minutes

    I could have gone longer in the bath, but the sign did not need it. The darker areas remaining are bare metal where the rust used to be.
    Attached Files
    My Meager Collection:

    I think they turned out ok.

    That paint & some of the markings seem to have come back & look brighter.

    I’d be happy with that result.

    Collector of Wehrmacht Optics, Ordnance & Field Equipment.


      Thanks for the tip, always looking for something like this.
      Be worth a try.
      Lookin for Reichsbahn Items and Luger mag E/63 5662W


        There wasn't much effort involved in doing this, so even the slightest improvement was worth it. Hopefully you guys find this helpful. If you try it, please post your results on this thread for others to see as reference.

        I also used the Oxalic Acid with a different method once before. I wanted to remove the rust from the handle, hinges, and clasps on the box below, but did not want to chance damaging the hardware by removing them. As a result, I could not make a Oxalic Acid bath to soak them in. Instead I used just a few drops of water on a small amount of Oxalic Acid in a paper cup, and made a paste. I applied that past to the hardware with a small brush like toothpaste and let it sit. I had to keep adding a little more water and OA over the couple hours I left it on, just to keep it coated, as some would flake off as it dried.

        Again, you can judge the results from the pictures below.

        *** If you try using Oxalic Acid, keep checking on your items every few minutes. Sometimes if the item is left in the bath or coated too long, a yellowish film can develop that is difficult or even impossible to remove on some items. Baking soda may neutralize and remove some of it, but I had a problem on aluminum parts.
        Attached Files
        Last edited by WWIIBuff; 09-17-2019, 01:29 AM.
        My Meager Collection:


          Wow - your wooden box really cleaned up nice; great result on the metal fittings!


            I agree, a big improvement! Looks great.
            Looking for a 30 '06 Chauchat magazine.


              Hi their,

              I read this with interest at lunch break today and looked to se if I can get it in UK.

              I can get it over here as it is also used for cleaning wood of corrosion stains etc.

              One very interesting thing I saw on the net cross referenced to your comment on aluminium and a yellow film. OA is also used in the process of anodising on alloy components. My thoughts on this aspect was to do a trial to see if it could be used as a poor mans restoration of the colour on the alloy laffette components. Some of which are a yellowy gold colour.

              Depends on the colour it comes out of course and definitively NOT on an original component as a trial

              Ive got a nice bit of kit that could do with the rust killer treatment so will give it a go. Thanks for the info and the "paste" method.

              Good post well illustrated


              Last edited by timg; 09-17-2019, 02:48 PM. Reason: spelling


                John, what do you do after cleaning the items with the oxalic acid? you leave them as they are? oiling?
                looking for a FJ medic bag


                  Originally posted by oberjaeger View Post
                  John, what do you do after cleaning the items with the oxalic acid? you leave them as they are? oiling?
                  I use Oxalic from time to time as well. It is a must to neutralize after the Acid Batch. Lots of (destilled) Walter. Then it is recommendable to put a thin film of oil on the item.

                  That´s my thought and way of working.


                    As Martin has said, it is definitely important to neutralize the acid after the rust removal is complete. I use distilled water or a mix of regular water with baking soda. Use caution with baking soda, as it sometimes leaves a residue.

                    Afterwards, dry the item thoroughly. Depending on the type of items, using paper towels might be sufficient, but I usually also let the item sit in the sun for a why as well. If there are grooves or other areas where moisture can hide, I would recommend hitting those areas with a blow-dryer and then laying it out in the sun.

                    Whether to coat the item with a protective matter or not depends on the type of item, personal preference, and where you live. I live in a fairly dry area, so I leave many of the items pretty much as they are, but you could also coat the item with a light oil or Renaissance Wax.

                    *** It is also important to neutralize the leftover Oxalic Acid bath water before discarding it. For this I add baking soda.***
                    Attached Files
                    Last edited by WWIIBuff; 09-20-2019, 12:18 PM.
                    My Meager Collection:


                      I can confirm wax is the best way to protect your items. You can use colorless wax for furnitures and antiques. Renaissance wax is better quality in my opinion but it's more expensive than a standard wax. No oil !!!!


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