Electrolysis

I used electrolysis for removing rust and to further clean the drill press. It is the best method I’ve found for removing rust. I’ve tried solutions to remove rust, citric acid, and others and found this to be the easiest. Although, there are a few negatives to this approach. It is best done outside, as hydrogen and oxygen gas is generated in this process, which are explosive, so I usually do it on a nice summer day out in the yard so the gases can escape safely. 

First you need a container to hold the item to be cleaned. I use a large plastic container. Fill the container with the desired amount of hot water (I use hot water to help the washing soda dissolve faster), then add the washing soda (I use Arm and Hammer) to the water. I use a fairly strong solution and don’t usually measure the amount of washing soda. I mix it near saturation then place the item in the water.

Once the item is in the solution, you need a power source and some scrap steel to use as an anode. I have a large 12 volt 20 amp DC power supply I built sometime ago for another project, but you can also use an automotive battery charger. For the scrap, I usually use chunks of mild steel I seem to find sitting around at work or around the home. The process works mostly in line between the anode and the object to be cleaned, so I usually use several anodes to surround the object. You need to connect the negative to the item to be cleaned and the positive to the scrap (anode). If you are using several anodes, place jumpers between them. It is important to keep the object to be cleaned and the anode separated in the tank or they will short out the power supply. I have a current meter on my supply and monitor the current draw. The current will drop off through the process, which usually means the anode is dirty and needs to be cleaned. Use a wire brush to clean it off periodically. It usually takes several hours, depending on the size of the object, condition, and current flow (which is affected by proximity of the object and the anodes). The power supply I use is large so it goes quite fast, with an automotive charger it may take longer. Just keep checking it until it looks complete. 

Once the item is complete, take it out and wash it off with hot water and a scrubber pad or a wire brush. This will remove any scale, which is easier to do now than later. Then dry the item with a heat gun, which removes water in the pores of the cast iron,  helping prevent rust when drying. 

Here is a picture of the my drill press going through the electrolysis process.

IMG 0231 (1)

During the process, I had to turn the drill press several times to get the whole body done, and limit the anode size to keep current flow down. I was using the wood to support the body to have it sit better. After the body was complete, I also did the gears and several other parts with this process as well.

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© Shane Larson 2018