As an objects conservator who spent many years devoted to metals conservation let me correct a few assumptions here. One must be able to distinguish between a stable oxidized patina and active corrosion. The term "rust" can mean both! If one leaves active or potenitally active corrosion on a ferrous object it will continue to corrode. Ferrous corrosion erodes under the surface of the object or artifact in the form of pits and it also can leach ferrous ions outward forming a corrosion crust. Corrosion is an electochemical phenomenon and is driven by moisture, the presence of acids and salts and pollutants, and oxygen. Also contact with dissimilar metals such as brass will cause galvanic corrosion. So if you wanted to preseve an artifact by leaving the rust in situ then keep it really, really dry and in an anoxic environment. To simply wax over a rusted or dirty surafce will certainly do more harm than good. So some sort of cleaning might be in order. if an oil is used then it should be a non-ionic oil (never orgainc) and should be formulated to lossen and stabilize corrosion products. That being said the current standard in terms of historic tool conservation is to carefully remove dirt and active corrosion but to leave a stable patina alone - so folks, put away your wire brushes and naval jelly. You also need to take care to protect any wooden components from and cleaning products used on the ferrous part of the tool.

That is about as specific as I can get without actually seeing the object. By the way, make sure you examine iron objects under very strong direct light - there may be more extensive corrosion than you thin if you are just seeing it under ambient room lights.

Cheers!
Dave

David Harvey
Artifacts
Denver, Colorado