Right say you had a pretty cheap silver coin with verdigris on it and you've got nothing much to lose by cleaning it. Afterall you have to clean it otherwise the verdigris will spread and destroy it. Lets say the silver purity is .900 or higher.

Could you clean it via a displacement reaction?

Silver coin, silver Nitate etc... or would it just make it worse?


A totally off the wall idea... the more i think about it the more stupid it sounds.

Silver coins can be Restored via Electrolysis.
Put some slightly salty water in a Stainless steel pot use a car battery and connect the + to the Coin and the - to the pot.
The current is supposed to remove the silver from the corrosion and plate it back on the coin.
I have never tried this so I don't know if it would work.

Yeah i'd considered that one.

Surely you'd need a silver containing solution to immerse the coin into though, otherwise where is the silver being plated onto the coin going to come from? (Unless it's coming off of the coin).

And the coin should be popped on the cathode i believe (-).

Na loses 1 electron to a non-metal meaning it becomes a + ion. Thus i would think most metals would follow that pattern of losing electrons and becoming + ions, thus the metal will go to the - rod so the coin wants to be on that one.

If i've got that all wrong never mind it's a long time since i did any science.

If you want to take metal off of the coin then stick it on the anode (+).

The prcess it supposed to recover any sliver content in the corrosion and plate it back on the coin not add additional silver from another source.
You are correct pluss should go to the pot and minus to the coin...
Anode Cathode ... Takes me back to a time when my brain used to work....

Come on you can't turn down an overweight coin can you?

I always remember is as Cations are Pussytive (ie positive). Everything can be worked out from there.

I read two recipes that sound as if they would work

1) put the coin on aluminium paper and poor salted hot water over the lot
reverse corrosion will turn silversulfide back to silver

2) put coin on aluminium and poor hot water with baking soda in it over the coin
same reaction

Since alu is less noble then silver it will oxidise and return the silver to the originale state

Actually putting a battery on the solution will work better but if you hoke up to the wrong anode/ kathode your coin will be completely pitted in a few moments

I have a friend who does this with old uncleaned roman coins
then you need bicarbonate or baking soda to stabilise the ph of
the mixture and even so you need to change the solution every
30 minutes
He uses a 220 volt AC converter to DC
Works very well

Ahem....Don't try this at home. Actually the electrolysis process is more complicated. You need an non-conductive container, a small ferrous plate for an anode and the coin should be placed in a screwtop type silver frame and suspended in a solution of sodium carbonate and water (not salt).

Any DC power source will work in such a small rig so long as the source is manually operated. I can do this for you if you need it done, but for a little spot of green copper bloom, soak your coin in ammonia or dip it in Tarnex and the result will be fine. Anyway, I'm of the opinion that verdigris won't eat a silver coin the way it will a bronze or copper coin.

It won't be as 'aggressive' since the silver is in the way, but on a .500 silver piece half of it is copper, on a .900 silver piece 10% is copper. If the copper has migrated to the surface then the coin is in trouble.