I can almost read the controversy now about the below methods for removing rust. But, they do work.
There are lots of ways to remove rust. On some iron objects that I find, like for instance, axes, hatchets, PIECES of cannonballs and shells, and other objects that are heavy and encrusted, I simply throw them in a big hot fire. Heat will cause the metal to expand and much of the rust will just pop off. You can also use a cutting torch if you are careful. I worked with a torch for 35 years and have removed much rust from metal working as a Boilermaker. Just fire the torch up like you are going to cut metal, press down on the slipstream lever and warm the piece up. The pure oxygen will cause all of the rust and scale to just pop off, or you can work it with a slag hammer or wire brush while you are doing so. Only use a torch if you know how to use a cutting torch or you could accidentally cut into the object. The idea is to warm up the rust and scale and blow them away with the oxygen, never heat it to any degree of redness. You can also use a small propane or mapp gas torch, but beware, as the piece heats up, the rust will pop off and when it gets in your eyes it sticks to your eyeball and you must get it removed by a doctor, so if using any type of torch wear a welding hood or safety glasses. Only use these methods on large encrusted pieces that really have no value. These methods will clean the rust off easily. If you use these methods on small pieces or lightweight pieces you will probably warp or ruin them. Only on large pieces of metal. If you want to try it sometime use an old horseshoe, as relic hunters, we all have found our share of horseshoes. Never use fire or heat on Civil War ordnance.
You can also use a wire brush, hammer, chipping hammer, power brush, electrolysis, or many other methods to remove the rust. If using electrolysis you must have an attachment point for one of the electrodes. I know some people will drill a small hole in the piece and attach a wire to it when a clamp cannot be attached, I do not like to destroy artifacts in this manner, although the hole can be very easily concealed and no one will ever know it was drilled.
Now the reason I am responding.
Once you have the rust off the object what are you going to do with it then? You must have a plan of attack for the relic or artifact. Simply removing rust will do nothing but cause the piece to rust over again. I never try to remove all of the rust. I just remove all of the dirt and then remove the scale or large pieces of rust until the object is absolutely free of loose rust. There are many methods to preserve a de-rusted artifact. The method I use is to dip it or thoroughly paint it with a rust stabilizer which turns the rust into a protective layer. This chemical can be purchased at auto parts stores. Once that is accomplished you can leave it alone or spray it with a clear lacquer, or wax, or any other method you may want to use.
Years ago I cleaned many of my relics and then painted them flat black. They are still nice and black, but really look painted. Many older relics were painted years ago and then a date and location were very carefully printed on the relics. You see these in pictures of old civil war relics. They look great to this day, but that method is not used much anymore. As for the relics that I painted. I plan to remove them from my frames, remove the paint, and let them rust over again and then preserve them as they should be preserved. Reminds me of my first minnie balls that I found in 1970. I took the whole lot and put them on the stove in a pot of soapy water and had the cleanest shiniest bunch of minnie balls you have ever seen. Today the minnies have mostly regained their white patine, (thank God) so all I use now is a toothbrush and nothing harder than a toothbrush.
You learn through your mistakes and painting and cleaning artifacts can truly ruin any value that may otherwise have been there. Your in the right spot for lots of expert advice.
heres a few links to look at 8)
I actually know what it is 
I'll give it a try!
