Rust removers are fine for spot cleaning. But if you have a big job, rust removers become costly and hard to use. I’m a part time metal sculptor, and I spend an embarrassing amount of time scrounging around for old iron and steel to tinker around with. Most of them are rusted. The best way to get rid of the rust is to electrocute the parts. All you need is a car battery charger, a container and a little metal. This method removes rust and paint and you won’t have to work with noxious chemicals.
Mix a Solution to Clean the Rust
Get your hands on a large, sturdy plastic container. It has to accommodate the submerged part with plenty of wiggle room to spare. Place the part in the container. Fill the container with water to within two inches of the top of the part. If you can, arrange the part so that only a small rust-free part sticks above the water. If that’s not possible, don’t worry, you can rotate the part later. If you have lots of small parts like nuts and bolts, place them in a wire basket and keep the top two inches of the basket (of it’s wire handle) above the water. Now take the part out.
Add one tablespoon of washing soda (sodium carbonate, not baking soda) per gallon of water. If you’re lucky, you’re plastic container’s volume is listed in gallons. If not, measure the volume in inches. A container holds roughly one gallon of water per 250 cubic inches. Stir the mixture until you can’t see any more washing soda.
Clamp a long piece of non-galvanized steel or iron to the side of the container (this piece will corrode during the process so only use scrap metal). The piece must be tall enough to stick three or four inches out of the water. The more submerged metal surface area, the better. Thin or short pieces will still work fine, but you may have to change them as they corrode. Or, clamp a few pieces of thin metal to the side of the container and connect them with a piece of 14 gauge steel or copper wire.
Put the rusted piece back in the water. Orient it so that it doesn’t touch the clamped metal piece on the side of the container. Make sure it’s resting and secure. You don’t want it to slide over and touch the metal piece at any point in time.
Place a car battery charger near an outlet but don’t plug it in. Place the black clamp on the rusted piece or the basket. Place the red clamp on the long piece that’s clamped to the side of the container. Now, occasionally, your clamps won’t fit. That’s an easy fix. Use a piece of 14 gauge steel or copper wire to bridge the gap: wrap one end of the metal wire onto the metal piece, then clamp the charger’s clamp onto the free end of the wire.
Plug the battery charger in. Bubbles are going to start coming off of the metal pieces. If they don’t, check your setup. Watch the charger’s meter. If it’s maxing out, turn the charger off and rearrange the metal pieces so they don’t touch.
Now crack open a good book, or start tinkering on a new project while the electricity removes the rust. This may take one or two hours. Don’t leave the setup unattended for long, especially if you have kids, pets or a curious spouse. You’ll know the part is done when the red rust turns black.
Turn the battery charger off. Remove the clamps. Lift the part out of the solution. Place it under running water and clean the black stuff off with a sponge or wire brush under running water. It comes off really easily. Towel dry the part, then coat it with oil or another rust preventing solution to keep it from developing more rust. Dump the washing soda solution in the yard.