Electrolysis for Rust Removal – Coffee Container





Introduction: Electrolysis for Rust Removal – Coffee Container

About: I like to design and build random things.

I’ve recently started the restoration of an old truck. As part of the restoration, I need to remove rust from many of the parts. I’ve read multiple blogs and instructables on this topic so I thought I would give it a try. For a proof of concept, I made the simple almost free version (minus the battery charger) shown here. I plan on building a large scale version similar to the others shown online in the near future.

Video of the Process:

Step 1: References

I’m not going through the detailed process or the FAQ since I think they have been covered in the referenced links pretty well. This instructable just goes through the small scale build. I strongly suggest you read the referenced material before building your own setup.


Other Resources:

Step 2: ​Tools/Materials:


  • Drill & Bit
  • Scissors


  • Battery Charger
  • Coffee Container (48oz)
  • Washing Soda
  • Zip Tie
  • Plastic Sheet
  • Wire
  • Electrode (sacrificial metal)
  • Work Piece (rusty part)

Step 3: Container Build

If you follow me, you might know that I recently acquired a large trove of plastic coffee containers. I’m almost out and I’ve been told by the wife to stop bringing them home. Anyway, this container works great for small parts and was perfect for my small scale test.

Step 4: Electrode (Sacrificial Piece of Material)

There is an old railroad track running through my town that is being converted to awesome project known as “rails-to-trails”. Walking the track, you can find steel railroad spikes that have been discarded over the years. I thought these old rusted relics would be perfect test pieces. If you can’t find spikes, use steel angle brackets, rebar or any other old piece of steel that will fit on the side of the container.

Step 5: Electrode Attachment

There is an open spot in the container between the handles which is perfect spot for the spike. I drilled 2 holes in the upper side of the container for a zip tie.

Step 6: Zip Tie

Use a zip tie to attach the spike to the container.

Step 7: Protection

To ensure that the electrode and work piece didn’t make contact, I used a plastic sheet (divider from a notebook) to cover the electrode.

Step 8: Add Protection

Cover the electrode with the plastic sheet. Note that it fit nicely between the handles and was held in by friction – no fastening required.

Step 9: Mixture

Fill the container with water. This is small scale (48oz container) so the laundry soda content is pretty small as well. Using the guidelines from the references, I decided 2 teaspoons would do the job.

Step 10: Battery Charger

This version has 3 settings (6V/6A, 12V/2A, 12V/6A) and cost about $30 from Amazon.

Step 11: Hookup

Connect a wire to the work piece and then to the negative terminal. I assume you could leave the negative terminal in the water but I wasn’t sure of the material and didn’t want to damage my charger terminal. Place the work piece in the container. Make sure it doesn’t come into contact with the electrode. Connect the positive terminal to the zip tied spike. Make sure the terminal isn’t in the water. Note that I used the 12V/2A power setting on the battery charger.

Step 12: Process

For safety reasons, move the setup to a ventilated area. Turn the charger on and wait. If it is working, you will start to see bubbles coming off the work piece. I ran the test for 24 hours and most of the rust was gone. I left it for another 24 hours and the work piece turned totally black. The electrode spike had a 1/8” thick layer of rust around it as expected. Note the rust in the on the top of water. There was also a decent amount in the bottom of the container.

Step 13: Cleanup

I used a scouring pad to scrub off the black layer. It washed up pretty easily.

Step 14: Final Pictures

Here is a comparison of the two pieces after the test.

Step 15: Electrode

Notice the rust buildup on the surface.

Step 16: Work Piece

It came out of test with a black layer. I scrubbed it under running water and this is the final result. The test worked as expected.

Step 17: Paint

I have no need for a railroad spike but I spent the time “de-rusting” it so I gave it a quick coat of black paint and then gave it to my daughter to paint.

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Could you harvest the red rust to use in a thermite reaction?

7 replies

I think it would work. Theres one thing that I think would be important in order for it to work ; you would need do dehydrate the rust. Just let it dry out in the sun, then pulverize it, then heat it up for a while on a stove (to vaporise the remaining water molecules). In fact i may try this myself, since you just made me realize that electrolysis could be a pretty good source of iron oxide for use in thermite...

Red rust it chemically fe3o3. Black rust is fe3o4. You need that extra oxygen to get the thermite to really get going. I've done it with the red stuff but it's not quite the same. If you add it to boiling water you can convert it to fe3o4. Or just buy it.

I think you have a typo there, its Fe2O3.

Oops. Nice catch. Those damn number 2's just scamper away sometimes.

Why are you talking about "Thermite"?

Because the person that I replied to was asking about thermite.

You may wish to reverse the electrolysis cell, and use a different electrolyte, and use a ferritic electrode you don't mind rusting away to nothing. Just saying.

A couple points: you want your work piece suspended free in the solution; if its laying against the sides or bottom this will leave those spots unaffected by the rust removal. If your work piece is a complicated shape, you may need to rotate it in the solution once or twice during the process to get maximal rust removal.

Do not use stainless steel for your anode; there are toxic compounds that can be released- use plain steel by preference.

The gas that is released during the electrolysis is HYDROGEN. This is EXPLOSIVE; do not do this in any enclosed space.

The closer your work piece (the cathode) is to the anode (the sacrificial piece), the quicker the rust will be removed , but if they touch, you may ruin your battery charger.

A 10 amp or larger charger is best for this process; smaller amperages still work, but take much longer.

. The more surface area is exposed on the anode, the quicker the process will work, i.e. several pieces of rebar wired together will work faster than one big chunk. An optimal configuration would be small pieces of rebar or something similar wired together all around the perimeter of your solution vessel, with the workpiece suspended in the center.

2 replies

Hydrogen gas has an explosive range of 4% to 75% by volume of the air in the room, collectively known as "Lower Explosive or Flammable Limit" (LEL/LFL), and "Upper Explosive or Flammable Limit" (UEL/UFL). There has to be enough hydrogen to burn, thus the lower limit, but there also has to be enough oxygen, thus the upper limit. Below 4% there is not enough hydrogen, above 75% there is not enough oxygen.

By the way, the same is true for all flammable gases and liquids. In the case of liquids, there is a minimum temperature which the liquid must attain to produce enough flammable vapor to burn. It is called the "Flash Point" (not the TV series). It is the vapor produced by the liquid that burns, not the liquid itself. Liquids with flash points below 100 degrees Fahrenheit are designated flammable.

Very good points!

how about making sure the box of white stuff's name is visble?????

1 reply

I made one of these many years back, I found the best thing to use is steel plate this increases the surface area there by speeding up the reaction.

Also buy a battery charger with a volt or Amp meter, if you see the needle or gauge starting to red line the is too much material in the bath and the fuse will blow on the charger or your charger will get damaged.


When you connect the work piece you must avoid plunging the wire because the copper may move to the surface of the work piece !

I use this for doing a sort of parkerizing (not sure how to spell it) for a couple of knife blades of mine. I remove the rust the same way to make sure it's gone, then purposefully re-rust it till it's all orange with rust. When placed in boiling water, the orange fe2O3 turns into black fe3O4 and it pretty resistant to the orange rust for quite some time.

How many volts and amps do you think I could use ?

Could I use a 55 gallon plastic drum and a stick welder ?

How much Baking soda would I need if I used 55 gallons of water ?

Thx in advance Ian.

2 replies

To be honest, I don't know the optimum power level. From research, the "more is better" has been stated in a few links. Others say to use the minimum to get the job done. As for ratios, the online range is pretty extreme. The minimum I found was 3.5 teaspoons per gallon. The max was 1.25 cups per gallon! My setup worked great but I assume there is an optimum point on power level and soda ratio where you would get the best results. Maybe an electrolysis expert (chemist) can chime in with a better answer.

Thanks for the information.