Cleaning procedures differ in their degrees of severity, ranging form soap and water all the way to stippers on wood; and from fine steel wood to sand blasting on metal. There is generally one criterion for cleaning wood or metal: the tool should be no cleaner, nor any dirtier, than it would have been when on a caring workman's bench when it was originally used. This means that while red rust or flaking corrosion on iron parts would not be acceptable, a gray oxidation would be normal. Bringing these parts up to a high polish is foreign to what the part ever looked like druing its working lifetime, and should be avoided.
CLEANING WOOD
Soap and water: takes off surface grime but not really good enough in most cases. It also tends to raise the grain of the wood.
Household Cleaners: are not bad, but are not effective with paint, tar and the like.
Linseed Oil and Turpentine: mixtures is popular, as it has both a cleaning and a preserving agent. Some people are opposed to the smell and the residue.
Strippers(liquid or paste): remove almost all problems except deep staining, but in many cases will also remove the patina. The patina is the surface change of the material brought on by years of oxidation and usage. It is natural to the piece and when it is removed, a "naked" look is created.
Expert restorers can duplicate this patina, but most beginners cannot. Most people feel that the piece is better dirty than naked, so if you can't get the patina back, doin't take it off. You might experiment with partial removal by paste strippers: the stipper is applied with steel wool and rubbed immediately upon contact. This may sound as if it won't work, because most stripper directions tell you to wait 20 minutes or so before trying to remove the finish. However, it works fine if you have a sensitive touch and just want to break through the outer grime. A good general rule is to test whatever you do on a small sample first and, when committed, to work gently and gradually. Always follow the safetly instructions.
CLEANING METAL
Brass and bronze can be cleaned with brass cleaners from the hardware store if the oxidation is not very heavy. If the crust is deep, industrial cleaners (heavier in acid content) can be used to quicken the job. Precaution must be taken with these cleaners, which require gloves, masks, face shields and proper ventilation. Rag wheels with cutting compounds such as tripoli or rouge will also remove oxidation but might bring the luster up too high. If the wheels are available, and the collector has the skill to use them, an udesirable luster can be killed with liquid cleaners. The biggest problem with liquid cleaners is they tend to get everything clean, even the recesses. These areas would not normally be clean in the life of the tool, and if every nook and cranny is sparkling, a very unnatural, naked look results.
Iron or steel can be wire-wheeled if a fine enough wheel is used. Experiment with wheels that do not take off more than you want. Remember, the difference in the hardness of the steel will give you a difference in results with the same wheel. If the wheel is not coarse enough, it will merely burnish the rust into the surface and you will defeat your purpose. (Some wheels are so fine, they will hardly break your own skin.) If the surface is exceedingly rusty, you might start off with emery paper, or use an old knife blade to loosen rust spots, until you're down to where wire wheels can be used. This takes sensitivity and skill---if you break thorugh the patina and leave a shiny spot, your in trouble. It's possible to acid etch the spot back to gray again, but this is not desirable.
Most people do not recommend sand or glass blasting, or using chemicals such as "naval jelly." All the natural life of the piece is destroyed with these techniques.