I use this to clean ancient roman coins that have a thick build up of sediment on them from sitting in the ground for thousands of years.
WARNING: some people do not like this method because they say it leaves the coin in much worse condition than if you used much slower methods. I got coins off of eBay for cheap so they probably don't have much value at all so I wasn't worried. I just wanted to experiment.
WARNING: there is low voltage electricity involved here, not enough for electrocution but enough to short out battery's and cause a burn or fire hazard if handled poorly.
WARNING: do this in a well ventilated area some dangerous gases can be produced.
Step 1: What You Will Need
-Tape - preferably electrical.
-Conductive wire - in a pinch you can use tin foil rolled into a wire but ideally you want wire meant for use In electrical components.
-Tin foil- used for connecting batteries together.
-Table salt- at least 2 table spoons.
-A container that holds a little more than 1 cup of fluid.
-Something you want to clean.
Step 2: The Battery Pack
Note, this entire step can be skipped by using a single 9 volt battery.
Start by making two 3 volt batteries by taping two batteries together by attaching the negative side of one battery to the positive side of another as seen in the second photo above.
Now tape those two battery packs side by side with the positive on one pack facing up and on the other battery pack facing down.
To complete the circuit as a 6 volt battery take a small piece of tin foil folded a few times and place it over either end of the battery packs connecting the positive and negative then tape it in place. This can be seen in the 3rd photo above.
Finally depending on what your using for wiring make easy connections on the remaining open side of the battery packs. I was using wire with alligator clips which I recommend for ease of connecting the wire to your objects. If you are just using wire by its self I would tape the wire directly to the open ends of the battery. This can be seen in the final photo above.
Warning: when connecting your wire or tin foil to the final open end if the batteries make sure these wires don't cross or your tin foil doesn't go across both battery terminals. Doing so will cause a short and your wire or foil will get very hot causing a fire or burn hazard.
Step 3: The Water Solution
Step 4: Starting the Process
With your wires hooked to the battery pack put both ends inside of the water solution and note which side fizzes. This is the side you want to hook your coin or object to.
Now attach your coin or object to the side that fizzed and put it in the water. If your using an alligator clip attaching the coin is easy. If not wrap your wire around the coin until it is secure.
Finally put your other wire into the water never letting it contact your object or the wire it's connected to.
Now let it sit for about 5 minutes then pull the object out and clean it off with an old tooth brush. Repeat the process until you get the object to the point you desire.