Our climate has routinely high humidity with the attendant rust concerns. You can almost completely eliminate rust with proper tool storage and appropriate preventatives. Using cabinets for tool storage increases rust formation unless they are airtight and incorporate dehumidification. Water in cabinet materials touching the tools creates galvanic pathways that encourage rust. Water transferred from hard working hands often raises the humidity level inside toolboxes to be higher than the surrounding room. Instead, store tools out in the open with good ventilation so you only have to deal with water vapor. Do not leave tools, wood, or excessive dust on cast iron machine tables. Protect your tools from rapid temperature swings that could cause condensation.
Rust preventative selection depends upon how the surface or tool is to be used. I have settled on the products and procedures listed below. The term "steel" refers to any ferrous metal that can rust. Keep the cans handy for frequent reapplication.
- Steel that does not receive wear should be primed and painted. Use red iron oxide primer labeled for rusty metal even if the surface has been freshly cut and filed.
- Steel surfaces that contact wood should be protected with a preventative that does not interfere with wood finishes. I use TopCote; Slipit or Renaissance Wax should also work well.
- Cutting tools need extra lubrication to reduce feed forces and pitch buildup. I have good luck with DriCote on chisels, bits, and saw blades.
- Metals that do not contact workpieces can be protected with a less expensive drying lubricant/rust preventative like Starrett M-1 All Purpose Lubricant or LPS 1 Greaseless Lubricant. You can save money and clutter by using these products for all exposed steel if your finishes and glues are not affected by them; M-1 is very economical in bulk quantities and a refillable spray bottle. Avoid products with silicone.
- Exposed steel that is not being used should be protected with a heavy film-forming rust preventative that can be easily removed before putting the machine back into service. I have been pleased with LPS Heavy-Duty Rust Inhibitor.
Wood in long term contact with tools can be finished to reduce moisture transfer. An alternative is to use teak for these situations. Teak is the only wood species that does not encourage long-term galvanic corrosion, which also makes it a good choice for mechanically fastened outdoor furniture. These steps will reduce your problem, but you cannot completely prevent rust formation. The tedious and anxious race to rub every last grain of rust from your tools will probably do more harm than good. Rust does not cause rust; regard the occasional spot as graceful aging.
Dave Wright - 7/10/98