Sword Rust Removal
Rust may be removed from your swords by either chemical or abrasive cleaning. Regardless of method, cleaning has its risks. Proceed with caution. Improper use or attention may damage your blades and/or their temper.
Rust removal methods are given weakest method to harshest. Always start with something weak -- it's easier to take rust off than to put steel back on. BTW, we haven't tried most of these, and use caution with any chemicals.
You can use a Sword Cleaning Kit or Nev-R-Dull for a mild chemical cleaner. It removes light surface rust and dirt, and is safe to use. It is available at your local automotive store and I believe it is cotton with a penetrating oil. It is oily feeling and leaves a slight residue on anything it is rubbed against. Rub the rusty area with a small piece and then wipe it off. Great for removing rust caused by light handling or humidity. Always test it on a small area if in doubt. Not recommended for blued blades (haven't tried it). I have also heard of a product called Flitz Metal Polish . ( recommended by the manufacturer in Toledo , Spain )
Solvents. The only one I've heard of using is kerosene. I've heard that if you soak a blade in it for a few weeks, the rust will come right off. Anyone care to verify that?
Acids. Yup, you read that right, just be careful and go slow. Start with some mild household acids -- try lemon juice first. It may take a few days, but check it periodically. Next would be vinegar (mild ascetic acid), and then Worcestershire sauce. My preference is a mild solution of carbonic and phosphonic acids that goes by the trade name of Diet Pepsi (takes about 3 days, followed by some steel wool and nev-r-dull). If those don't work, A 1 molar solution of a medium-strong acid, such as muriatic or phosphonic acid, will slowly eat away the rust. Check your pool supply store for these. They may take a few hours, but check them regularly! They will eventually eat into the blade if left too long. Strong HCl will eat the rust off in seconds (I use it to clean rusty tools at work), but I do not recommend this method for use on a sword. A strong acid will leave microscopic etching, which will give a dull, leaden look to the blade.
Electrolysis is the process of breaking apart the rust molecules into iron and oxygen, then binding the oxygen to a more active metal. One method is to immerse the blade (remove the handle first) in a slightly basic solution (caustic soda or lye) while it is surrounded with metallic zinc. The reaction will eat the rust and produce zinc oxide. It is important that a basic solution is used to prevent further rusting of the steel, and make sure that the surface to be oxidized is a more active metal than iron. Check a college chemistry book when in doubt. Do not use aluminum foil, because it is more stable than iron and will cause the iron to rust away. The process takes a few hours, so check it regularly. The process can be speeded up by connecting a car battery to the apparatus as such: negative to iron, positive to zinc. I have been told that electrolysis can leave a blade looking 'cooked,' and that it destroys the original temper of the blade.
I've also been told that exposure to high heat will remove rust, but this will discolor the blade and destroy the temper.
Oil and steel wool is the most often prescribed way to remove light surface rust. You know how to use it already, so there is no need to say more. Scotch-brite pads and olive oil make a good alternative, for the more kitchen inclined collectors.
Rubbing the steel with a piece of copper will remove rust as well. Since copper is softer than iron, it won't scratch the surface, either. I have never tried it before, but I don't think it would take off any patina.
A soft wire brush works the same way, and may be useful for a sword that is already heavily pitted or scaled with rust. The bristles shouldn't put enough pressure on the steel to scratch it, so it should be ok. I have seen wire wheels for drills, and they might work as well. Test it on a small area first before attacking the whole blade.
Polishing stones are used in knife making, and will give a mirror finish to the blade. Remember, though, that this may actually detract from the value of the sword. Also remember this -- it takes a 5-year apprenticeship to learn to make a Japanese sword, and a 10-year apprenticeship to learn to polish one. 'Nuff said.
I assume that abrasive cleaning compounds might work, but that they would leave scratches on the blade. Test a few out if you want to try this method.
Very fine grit sandpaper will leave scratches, but it is good for a hard assault on scaled rust. Be careful to only be rubbing the rust, though.
Grinding wheels. Don't make me have to hunt you down and smack you over the head. I once saw a Civil War recreator who was proud to be carrying an authentic M1860 cavalry saber. He had cleaned it on a bench grinder. He sure was proud of himself for destroying a piece of history. He also had it and its scabbard nickel plated. That guy shouldn't have been trusted with a replica saber. Grinding wheels are great for sharpening lawnmower blades, but if you feel the need to put your sword against one you should really consider a different hobby.