Instead of polishing or acid etching off precious silver or potentially damaging set stones or other features on the items, we will use electrolysis to instead convert the tarnish (silver sulfide) back to silver metal!
I will demonstrate two different methods for doing this. In the first method, which works best on only lightly tarnished items, we won't even use a power source to perform the electrolysis, relying on the properties of two metals to pass ions between each other. In the second method, I will show how more aggressive cleaning can be done with a DC power supply, such as a 4 AA battery pack.
Once we complete the electrochemical conversion of silver sulfide to silver, we might want to remove surface scratches as well, in the case of items like jewelry, and for this I have chosen a Dremel with buffing wheels and compound, but you can use a jeweler's cloth as well.
What you will need:
Common for Both Methods
- Baking Soda (sodium bicarbonate)
- Salt (sodium chloride)
- Pitcher of Warm Water (heat increases solubility)
- Wooden Spoon (or similar, to stir water with)
- Large Non-Metallic Dish (Pyrex or glass recommended)
- Old Toothbrush or Similar Item
- Soft, Clean Cloth
- (Optional) Dremel or similar tool and accessories to buff the end result
- Tarnished Silver to be Cleaned
- Aluminum Foil (aluminium for readers across the pond)
- Copper Metal (scrap PCB, pennies, plumbing scrap - will be damaged in process)
- DC Power Supply (4 AA holder with switch recommended)
- Alligator Clip Jumper Wires (optional - cathode may rust during cleaning)
Step 1: Basic Method
- Add a few tablespoons of salt and baking soda to the warm water and stir to mix it. This will help our water carry electrical current (even without batteries, we are utilizing electrical activity).
- Press the aluminum foil into the bottom of the glass dish.
- Pour the doped water into the dish, adding enough to completely submerge the aluminum and the item to be cleaned.
- Place the item to be cleaned on top of the aluminum foil, ensuring there is electrical contact between them. They should touch in a relatively clean spot.
- Watch as the aluminum gives up ions to the silver, causing the conversion of silver sulfide to silver metal again. In a little bit, your silver will be ready for cleaning with clean water, a toothbrush, and a rag to remove dislodged bits of dirt and oxides.
Once you wash the item, it should be shiny and clean again. If it has a lot of scratches from wear, buff it gently with a jeweler's cloth or use a rotary tool and buffing attachments to get it smooth again.
Step 2: Advanced Method
- Just like we did for the basic method, add a few tablespoons of salt and baking soda to the warm water and stir to mix it. This will help our water carry electrical current (even without batteries, we are utilizing electrical activity).
- Attach a piece of copper, preferably with a large surface area, to the positive terminal of the DC supply. I used alligator clip jumper wires. Place the copper in the bottom of the dish.
- Pour our doped water into the dish, adding enough to completely submerge the copper and the piece to be cleaned.
- Attach the negative terminal of the DC supply to the item to be cleaned. Again, alligator clips help. Submerge the piece to be cleaned, making sure it does not touch the copper, but is near it.
- Watch as hydrogen bubbles, dirt, and oxides are blasted off of the surface of the silver, and the tarnish becomes shiny silver once again.
If you want to remove surface scratches and restore luster, simply polish lightly with a jeweler's cloth or rotary tool.
Step 3: Conclusion and Results
We have successfully cleaned out jewelry in a non-destructive manner with amazingly little effort. As you can see in the attached images, this worked really well on some old and heavily tarnished jewelry. The largest ring with the big gemstone was restored as well, retaining its intentional patina in the crevices of the pattern but it looked so good when I finished that my mother-in-law swiped it before I could get a picture. Special thanks to Nurdrage for the inspiration behind this.
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