At first I was skeptical to electrolysis. I consider this as a”barbaric” method of cleaning. However, I decided to try it.
As a test subject i chose the 15 kopeks silver coin 15 from 1926, with a silver purity of 500. The condition of this coin was no good- it was more dead than alive. There was black tarnish on it, which had previously tried to remove with a little citric acid. There was also some “rust-like” plaque on the reverse side of it.
As for the set-up, it is very simple. The power supply was an ordinary phone USB charging cable with 5V, 1A. I cut open the cable and separated the black wire, which is ground, from the red one which is VCC. For ease of use, I picked up two thick copper wires (brown and blue, for “plus” and “minus”), and two crocodile clips.
I used a plastic bowl, which i filled up with water and a tablespoon of baking soda and mixed it together. Instead of soda people often use ordinary table salt. Be careful not to use any metallic bowl for this! Rather use plastic or glass.
Next on the “plus” I attached a silver “scrap piece”, and on the “minus” i attached the coin. Do not let the two sides touch, as you will get a short circuit. After switching on the power i immediately noticed bubbles at both ends. This is a good sign that the electrolysis works. The water releases hydrogen, so try to ventilate your location.
It is also essential to remember that our coin must be on the “minus”! The scrap piece which i attached to the “plus” began to actively break down and being covered with a blue plaque, which I believe is due to the use of in my case, baking soda. The process is shown on the picture:
I kept this going for about 20 minutes, then i disconnected the power. During this time the coin had been covered with a thick black coating. This I cleaned off with an ordinary toothbrush and water. And here is my final result. Not bad i would say.
What do you think of the electrolysis as a way of cleaning coins? Have you ever tried it?