How to Remove Rust Using Electrolysis

Two parts of a rusty pair of pruners: one before electrolysis, one after
Two parts of rusty pruners: before electrolysis (top) and after (bottom)

Electrolysis is a simple and effective way to remove rust and restore metal without damaging the surface as sanding or scraping would. Electrolysis works best on iron and steel. Do not attempt electrolysis on stainless steel, since it can release toxic chromium gas.

How Electrolysis Works

Electrolysis occurs when a low-voltage, direct (DC) electrical current is passed through two pieces of metal suspended in a chemical (electrolyte) solution. The current causes a transfer of ions between the two pieces of metal which breaks down rust on the metal connected to the negative electrode (cathode) while corroding the metal connected to the positive electrode (anode).

Since electrolysis doesn’t affect the underlying metal, it’s perfect for cleaning tools, restoring antiques, and loosening rusted bolts.

Read on to find out how to remove rust with electrolysis.

Materials needed for electrolysis
Materials needed for electrolysis

Materials Needed for Electrolysis

Electrolysis should be done in an area with plenty of ventilation, since it releases small amounts of hydrogen and oxygen gases, which could be flammable if they build up.

To remove rust using electrolysis, you will need:

  • Battery Charger: A basic 12-volt car battery charger will do the job.
  • Electrolyte: Washing soda (sodium carbonate), such as Arm & Hammer Washing Soda, is the best electrolyte to add to water for removing rust. It’s sold as a laundry booster, and can be found near laundry detergents in stores.
  • Water: Warm water will dissolve the electrolyte faster, but tap water is fine.
  • Cathode Metal: The tool or other metal item you would like to clean.
  • Anode Metal: A scrap piece of iron or steel (not stainless steel). The anode is reusable, but it will be gradually eaten away over time, so don’t use anything important! A piece of steel rebar is inexpensive and works great. Since the side of the item facing the anode will be cleaned faster, you may want to connect multiple anodes together with copper or steel wire, or use a piece of sheet steel bent around the item you’re cleaning, to make the process more efficient.
  • Nonreactive Container: A plastic storage bin or bucket is perfect. It needs to be large enough to hold both the tool and the anode without touching.
  • Twine or Plastic Clamps: Used to suspend the tool and anode in the water.

Read on to find out how to set up electrolysis

Step 1: Disassemble Rusty Item

Step 1: Disassemble Rusty Item

If the object comes apart, disassemble as much as you can. Plastic handles will probably do OK in the bath, but wood and leather should be removed or kept out of the water.

Step 2: Mix Electrolyte Bath

Step 2: Mix Electrolyte Bath

The electrolyte solution should contain one tablespoon of washing soda per gallon of water. Stir until the soda is completely dissolved.

Step 3: Suspend Rusty Item

Step 3: Suspend Rusty Item

Suspend the item in the solution so as much of the surface is exposed to the water as possible. I used twine, but you can also lay a board across the top of the container and hang or clamp your tool in place.

Make sure to use nonreactive plastic, wood, or twine. If the object won’t fit completely in the container, leave part of it out of the water and clean it in stages.

Step 4: Position Anode

Step 4: Position Anode

Place the anode in the container so one end sticks out of the water. Position it a couple of inches from the rusty item, making sure they do not touch! You can also use twine or plastic clamps to hold the anode in place.

Step 5: Connect Negative Electrode

Step 5: Connect Negative Electrode

Connect the negative (black) clamp from the battery charger to the rusty item. If the item protrudes from the water, put the clamp on the dry part. While the negative clamp can to be underwater, it might cause it to eventually wear out.

Step 6: Connect Positive Electrode

Step 6: Connect Positive Electrode

Connect the positive (red) clamp from the battery charger to the part of the anode that’s protruding from the water, so the red clamp remains dry. Don’t get the two clamps mixed up, or you’ll end up with a really clean piece of rebar and a disintegrated tool!

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