Rust
Iron and steel don't exist in nature in pure form and are not stable,
quickly decomposing with air and moisture into iron oxide -- rust.
Steel tools that cut plants and bite into soil contact plenty of moisture and must be kept clean to prevent rust.
We've found biodiesel to be an excellent cleaner and lubricator -- unlike mineral oils, it's not toxic, ideal for organic growing. It protects against rust to an extent, but linseed oil gives better protection. Apply regularly.
... cleaned with lye and electricity
Here's a good way to remove all rust from steel tools. We've used it a lot
in restoring old tools deeply pitted with rust.
You need an ordinary car battery charger, lye (caustic soda -- sodium hydroxide) and a plastic bath -- a standard 25-litre plastic container with one side cut off makes a good bath. Work outside -- the process emits some fumes. WARNING: Lye is highly corrosive, even though this is a weak mixture -- wear rubber gloves, keep clean water handy.
Mix two tablespoons of lye with 10 litres of water in the bath. Attach the positive (red) terminal of the battery charger to a spare stainless steel kitchen knife or spoon and put it in the bath. Attach the negative (black) terminal to the rusted tool -- scrape some of the rust off first to make sure it makes good contact. Put the tool in the bath on a stone, not touching the knife.
Switch on the charger -- the rusty tool (and maybe the knife) should begin to send off streams of tiny bubbles. Leave it on for 24 hours. If it's a large tool, take it out after 12 hours and attach the terminal to the opposite end to spread the effect.
After 24 hours a lot of the rust will have flaked off, and the rest will have been converted to oily black stuff that can easily be scrubbed off in hot, soapy water. The tool emerges clean, all rust removed or converted, even into the deepest pinholes of corrosion.
NOTE:
We've tried to find out the composition of the oily black deposit left on
the tools, but without success. If anyone knows, please tell us -- thanks.
