The hectic pace of the summer garden season is winding down. You have harvested the remaining tomatoes and peppers, pulled up the dead plants, dug the late season potatoes, carrots and turnips. It seems there is nothing left but to wait for spring. Now is the time to pull out that jumble of hoes, shovels and rakes in the garden shed and clean off the accumulated rust you have been meaning to get to for years, all you need is a good method for doing it.
Sand away the rust with sandpaper and a considerable amount of "elbow grease." This is time consuming and requires considerable dexterity to remove rust from tight joints, around bolts and screws or between tines of forks, but it will work.
Clean and oil your tools simultaneously with a bucket of sand and motor oil. Fill the bucket with clean, dry sand--the smaller the particle size, the better--then add a quart of lightweight motor oil. Thrust shovels and garden forks repeatedly into this mixture until all traces of rust are removed. This will even help to renew the edge a bit, though you will still need to resharpen very dull tools.
Use steel wool or a wire brush on tools sprayed lightly with WD-40. Again this is work, but the results are good.
Coat metal parts with Naval Jelly, using a brush to reach difficult areas, and let stand for several hours before rinsing with clear water. Repeat as necessary until all rust is removed.
Dilute ordinary molasses with water at a ratio of 1 part molasses to 10 parts water, and allow metal parts to soak in this solution until rust disappears (which may take a couple of weeks in extreme cases). According to Bill Alleman of Tavern Village Forge, this works because "Molasses contains chelating agents. ...molecules ... shaped a bit like the claws of a crab. They can envelop metal atoms on the surface of an object, trapping them and removing them. Molasses owes its properties to cyclic hydroxamic acids which are powerful chelators of iron." Best of all, molasses is safe to work with and dispose of--simply pour on the compost pile. (See Reference 1)
Practice the "ounce of prevention" method. Stop rust in the first place, as the easiest and best method to keep tools rust free. Regular cleaning, followed by an application of oil or wax (auto paste wax or Butcher brand wax) will keep tools in top-notch condition.