Electrolytic Rust Removal

Electrolytic Rust removal is safe and inexpensive

If you have a bunch of old rusty steel you want to weld or you are trying to restore some antique tools, electrolytic rust removal is the way to go. If you have a battery charger that is not one of those “smart” ones and a 5 gallon bucket you are in business. You only need to pick an alkaline electrolyte such as baking soda or washing soda.By using electrolytic rust removal, you are also benefiting your health and the environment. You do not need poisonous and corrosive phosphoric, hydrochloric, or oxalic acids to do this. Whats more, hydrochloric acid(muriatic acid), although effective, etches steel bare and sets it up to flash rusting unless the metal is thoroughly rinsed, dried and primed or coated right away. With electrolytic rust removal, you get a black smut which easily wire brushes off and the metal can take a high polish if not pitted. If it is pitted, simply wire brush it clean and use a high buiild primer under regular primer.

 

Safety

type=textJust wanted to point out there are still some safety issues since we are handling electricity. The output of a battery charger is usually 6 or 12 volts DC and not too harmful, but the input 120 Volts AC that plugs into the wall is VERY dangerous especially around the water based electrolyte. So use common sense and keep the power source AWAY from the bucket of electrolyte so it does not fall in.Unless you are using a strong alkali like lye or Trisodium phosphate, the chemical hazards are minimal. Do not breath dust or get the powder in your eyes.

 

How this all works

basic electrolysis cellThe best way to understand what is going on is to consider the basic electrolytic cell. It consist of a nonconductive container that holds the electrolyte, an anode which connects to the positive pole of the DC power source and a cathode which completes the circuit by being connected to the negative pole of the power source.In electrolytic rust removal, the workpiece is connected to negative (-) and a sacrificial steel or iron anode is connected to positive (+). the electrolyte is made up of about a cup of either washing soda(sodium carbonate) or baking soda(sodium bicarbonate). It should be noted that the workpiece will have to be wire brushed or sanded in a spot in order to make a good electrical connection with negative connection. After time, a thick coating of rust will develop on the steel anode and it will slow down or almost stop the flow of electricity. Therefore, the anode should be periodically checked and scraped when necessary.
When powered on, the system will generate hydrogen on the negative workpiece which will disengage the rust particles from the metal surface while oxygen is liberated at the anode while it rust at an excelerated rate.

 

Tank setup

5 gallon bucket cellOk here is a simple yet effective set up to get started. As you can see from the photo of bucket cell, you have the 5 gallon bucket as your nonconductive electrolyte holder, a piece of scrap wood to attach power leads to so they can be hung over the bucket, and 3 lengths of rebar serving as the anodes here. They are cheap and readily available and make great anodes. It is a good idea to arrange them so the action from the electrolysis is evenly distributed around the surface of the workpiece.After you wire up all the anodes you will be using, together, you connect this to the positve(+) battery charger clamp. Next you connect some leads to the workpiece and suspend them into the electrolyte and connect to the negative(-) charger clamp. Now turn on the power and you should see gas bubbles rising up.

Let this go on for at least 4 hours or better all night while you sleep and then pull out your work piece to check. Depending on the thickness of rust, it might be all gone or you may need to scrub the metal a little and repeat.

 
 

The results

typical resultsIn the photo shown here, you see the results usually obtained. The top part represents the finish after wirebrushing. The bottom is after 15 minutes where the red rust is converted to black rust. The middle is where some oil contaminated prevented rust removal. It is a good idea to wipe down your workpiece with a shop rack with either denatured alcohol or acetone.

 

Sources of more information

Electrolytic Rust Removal aka Magic
A very in depth instructable on electrolytic rust removal.
Rust removal by electrolysis
Featured on Bill’s Antique Gas engines, this short yet consise essay will surely get you on your way.

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One thought on “Electrolytic Rust Removal

  1. KY Dave says:

    I ran into the problem that my charger wouldn’t work unless it was hooked up to a low battery. Had to switch to a “dumb” charger. ( http://davehallier.com/best-charger-for-rust-removal-by-electrolysis )

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