electrolytic cleaning of steel
This is a means of cleaning rust off steel by using an electric current. It is easy, fairly safe and removes no metal, nor does it interfere with the natural texture of the rusted metal: sand-blasting or emery tend to smooth out the metal surface a little. In the following example, a piece of rectangular section steel which was found on the beach is stripped back to bare metal.
DISCLAIMER: I take NO responsibility for any accident or injury caused by trying this out. What I have given below is my own personal experience. It is up to the user of this information to ensure that health and safety considerations are implemented. Voltage plus liquid can be deadly.
1) Preparation.
Here you can see the tank in my workshop, right behind my bench.
The tank contains dilute washing soda (Sodium carbonate). I use about 1 tablespoon per litre of water, but this is really not critical. On the left is a sheet of stainless steel, connected to the negative terminal of the power pack as the anode; on the right is the rusty bar, connected to the positive terminal of the power pack as the cathode.
The only really critical things are:
- The anode and cathode must not touch;
- The anode should be about the same or greater surface area as the item being cleaned;
- The item being cleaned should be scraped at the point of attaching the wire to the power pack to ensure a good contact.
- The anode should be either stainless steel or plain iron/steel.
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2) Power
The current is turned on to between 10-18 volts. A car battery can easily power this setup if a power pack is not available. The length of time taken depends on the amount of rust being removed. About 20 minues will be enough to loosen light rust. I have left the tank running overnight to remove heavy corrosion.
As the process removes no metal, it is quite safe to run it for prolonged periods.
3) Cleaning
The metal will, initially, turn black and pieces of rust will drop off into the solution.
This black layer can be removed by scrubbing gently with a wire brush under running water.
Leaving the surface clean.
If it is not clean enough, re-clean in the tank and repeat the scrubbing.
Leaving the surface which so appeals to me.
