Electrolysis: Mention the word to my wife or daughters and you'll be knee-deep in a discussion about hair removal. But to a gearhead it's all about rust removal. After stumbling upon a few late-night YouTube videos on the subject, I decided to give it a try.
The process is simple, as seen in the diagram to the right. Direct current (12 volt) is passed through water causing rust to release from a negatively charged item to a positively charged piece of metal (anode).
One tool I really wished I had room for in the shop is a media blast cabinet. That is the definitive means of prepping a piece of metal for paint, but media blasting can also affect the base metal's "complexion," while electrolysis will not. However, electrolysis will not remove dirt or paint and leaves a black discoloration which will need to be scrubbed or lightly sanded away. In any case, I wanted to give it a go with a few rusted bits from Project 39 — a rear brake rotor, torque arm, caliper mounting bracket and heat shield.
The process is simple, as seen in the diagram to the right. Direct current (12 volt) is passed through water causing rust to release from a negatively charged item to a positively charged piece of metal (anode).
One tool I really wished I had room for in the shop is a media blast cabinet. That is the definitive means of prepping a piece of metal for paint, but media blasting can also affect the base metal's "complexion," while electrolysis will not. However, electrolysis will not remove dirt or paint and leaves a black discoloration which will need to be scrubbed or lightly sanded away. In any case, I wanted to give it a go with a few rusted bits from Project 39 — a rear brake rotor, torque arm, caliper mounting bracket and heat shield.
Here's my basic electrical components; a battery & charger, two strips of scrap steel to act as sacrificial anodes and some lengths of wire with large clips. You can use the charger alone, set to about 2 amps, but I put the battery inline to act as an electrical "sponge," just like in a bike's electrical system. All I need now is a 5-gallon plastic tub and some lengths of wood to suspend the pieces in the water.
(Below) Here, I begin with the caliper bracket and snap ring. After adding warm water with a tablespoon per gallon of baking soda to form the electrolyte, I make the electrical connection. The close-up photo shows the telltale bubbling of the chemical reaction after only a few seconds. After about two hours of soaking, I removed the bracket from the brown, opaque solution and…success! The rusted spots were down to bare metal.
(click on images to enlarge)
(Below) Here, I begin with the caliper bracket and snap ring. After adding warm water with a tablespoon per gallon of baking soda to form the electrolyte, I make the electrical connection. The close-up photo shows the telltale bubbling of the chemical reaction after only a few seconds. After about two hours of soaking, I removed the bracket from the brown, opaque solution and…success! The rusted spots were down to bare metal.
(click on images to enlarge)
(Below) Okay, let's try some more serious items. With fresh solution I loaded the brake rotor, heat shield and torque arm, letting them soak all day. The muck that resulted told the story; that's a lot of rust removed. The anodes show how they sacrifice themselves to allow the reaction — these anodes will be sanded clean and used repeatedly. The dirty electrolyte is non-toxic and can be poured down a drain or even on your lawn.
After cleaning and sanding, here's some of the items ready for paint. Was the effort worth it? For items where I just can't reach the rust with sandpaper, like the torque arm, yes. The flat metal heat shield would have gone quicker with just sanding, but the rotor had shallow rust pits that I'm now confident are rust free.
If you're in a hurry, this is not your best approach — it can take 24 hours or even longer for severe rust removal, but for items like these, electrolysis can be a useful tool.
If you're in a hurry, this is not your best approach — it can take 24 hours or even longer for severe rust removal, but for items like these, electrolysis can be a useful tool.
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