For rust removal, try automotive brake fluid. For light rust rub it on liberally with a patch, allow it to sit for a couple of minutes and wipe off. For heavily rusted items swab liberally with brake fluid and allow to sit over night. Burnish the finish with a wool pad or #0000 steel or bronze wool. Brake fluid may be damaging to some wood finishes so make sure you keep it on the metal.
Electrolysis Rust Removal
You can remove rust from metal using electrolysis, and it will not harm the bluing. The main advantage to this method is it gets all the rust in hard to reach places. You will need
* A plastic container that will hold the part and electrolysis solution.
* Steel rod. DO NOT USE STAINLESS STEEL AS THIS WILL PRODUCE HARMFUL BYPRODUCTS.
* Arm & Hammer Washing Soda (not baking soda. Washing soda can be found in your local grocery store with the laundry detergent. If you cannot find washing soda, pour some baking soda-sodium bicarbonate into a pan and heat it over low-medium heat. Water and carbon-dioxide will cook-off leaving washing soda-sodium carbonate. ) Another source is swimming pool “PH Increaser.” which is labeled 100% sodium carbonate. [Thanks to Bob Head for this hint]
* Battery charger or other high amperage power supply.
Cautions: Wear eye protection and rubber gloves when working with this solution is very alkaline and can cause irritation. The electrolysis process breaks down water into its component parts, hydrogen and oxygen, which can be explosive. Work outside or in a very well ventilated area. Be sure your battery charger/power supply is unplugged before attaching or touching the leads.
In the container, mix 1 tablespoon of washing soda for each gallon of water to make up your solution. Be sure the washing soda is thoroughly dissolved. Place a steel rod either through the part to be cleaned (use o-rings to prevent the part from touching the rod), or numerous rods around the inside of your container. Connect these rods with wire; these will be the anode. You must be sure that the part to be cleaned is not touching the rod(s). Suspend the part in the solution with steel cable or wire so that it makes a good electrical contact with the part; this will become the cathode. Connect the negative lead (black) to the part being cleaned, connect the positive (red) lead to the rod(s), then plug in the charger. You will immediately begin to see bubbles; this is hydrogen and oxygen as the water breaks down. Allow the part to “cook” for 3-4 hours. The time is dependent on the size of the part, amount of rust, and the current of the power supply. After you remove the part, immediately clean and dry it off, then coat it with a good quality gun oil or rust preventative oil.
Thanks to Roy Seifert for this tip
Roy reports that he used this process on a 1911 frame that had a lot of surface rust all throughout the inside. He set the frame upside down on wooden blocks in the electrolysis solution and placed a rod with o-rings through the magazine well. He used a 1.5 amp trickle charger and left it for about 4 hours. When finished, the frame was completely free of rust, and the bluing was intact.