This is my favorite method to remove rust from very corroded metal pieces. it is very simple and very efficient, you may obtain spectacular results if you are patient.
WARNING: Use this method only outdoor in open space, highly toxic gases are released during the process.
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Step 1: What We Need
1. Baking Soda (i used 400gram for 10litre of water, but you can experiment with more or less)
2. Plastic bucket (it is important to be plastic, to be nonconductive)
3. 12V DC power source (i used an old pc source because it delivers about the amperage i need and it has short circuit protection)
4. Sacrifice metal (the rust will be transferred to it)
5. Copper wires
Step 2: Prepare for the Proces
Cut all the yellow wires from the source output and connect them, do the same with the black wires. Use the copper wires to attach the pieces you want to clean and connect with the black wires from the source. Use copper wires to attach the sacrificial metal and connect with the yellow wires from the source. Put water in the bucket and put the sacrificial metal inside. Make sure that they don't move during the process, it will create a short circuit if they touch the pieces you want to clean. Add the baking soda and mix it well. Put in the pieces you want to clean and make sure they don't touch the sacrifice metal. Check if all is ok and start the power source by connecting the green wire and the black near it (see last picture) . If it is ok after some time bubbles will appear on top of the solution.
Step 3: Electrolysis
The process we use is electrolysis. Electrolysis is a technique that uses a direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction.
Electrolysis is the passing of a direct electric current through an ionic substance called electrolyte (our :) baking soda mixed with water ) , producing chemical reactions at the electrodes and separation of materials.
The main components required to achieve electrolysis are:
An electrolyte: a substance, frequently an ion-conducting polymer that contains free ions, which carry electric current in the electrolyte.
A direct current (DC) electrical supply: provides the energy necessary to create or discharge the ions in the electrolyte. Electric current is carried by electrons in the external circuit.
Two electrodes: electrical conductors that provide the physical interface between the electrolyte and the electrical circuit that provides the energy.
Step 4: Results
I only left the source on for 2 hours, should stay about 6 hours on to get good result.
Results depend on how much you leave the power source on, but you can repeat the process if you are not satisfied. You can experiment with mixing more or less baking soda, using higher or lower amperage (about 10 amps is ideal, under 5 amps the process will not begin and over 15 amps the electrolyte solution will start to boil).
After you remove the pieces you can wash them with water and a brush.