I like this post LOL.
For those who are for artificial de-plating the CPZ. Can you name something which dissolve the Cu without attack very strong the Zn? NO you can not. Cu it is a very resistant metal to all kind of acids, bases, etc. The HCl will solute the Cu but will eat fast the zinc. Then which solution will let the surface smooth as come after polish? And also if was submersed in a kind of solute, why the stairs do not show some Cu residues or trace of an attack. Nitric acid, sulfuric acid must be heat and will solute first the Zn.
I give a solution for de-plating by reverse electro-plating, but this solution will be apply to all the coin and impossible just partial. Here what will happened:
Quote:
Electrons are flowing from more active (Zn) to more passive metal (Cu). This is essential for creating the electric electric current in the cell. In solution without a salt bridge you have constant concentrations of anion (SO4square minus). However, concentration of Cu2+ is decreasing (Cu deposits on metal) and concentration of Zn2+ increases (Zn dissolves). This creates charge imbalance that will quickly compensate difference in potentials of Zn/Zn2+and Cu/Cu2+.
So is not possible without attack the Zn.
In the processes of plating, if for one reason or other the Cu anions flow will pass to fast will deposit on the anode and cathode and the plating is stop. If the flow will be to slow the same effect will be. So if a coin start to be plated and the electrical differential change creating high or to low flow, the part of the coin will be plated and the other part no.
I stay with my first statement: this coin it is legitim.
Hope some more explanations will come.