Verdi_care Results - Brass

That's a pretty dramatic change on the 44. But, I not surprised. I still use it to conserve coins but I don't know how to avoid the discoloration that you experienced.

It seems that once Verdigris is really entrenched on a coin it permeates deep into the coin. When the solution is induced to the problem area, it almost looks as if some type of exothermic reaction changes the color of the metal. Or is it that the metal is cleaned to it's original color once the Virdigis is removed?

Any suggestions Bad Thad?

carmykle - I believe the red stuff is cuprous oxide. Unfortunately, it's impossible to remove without using strong acids which would really damage the surfaces.

As the verdigris grows, it pulls copper atoms from the surface forming a pit. The older the verdigris, the deeper the pit and the more entrenched it becomes. The pit also causes changes in the electrochemical properties of the corrosion causing it to accelerate it's development further.

If you can catch verdigris in the early- to mid-life stages, it can be successfully removed with almost no visable surface damage. When it has gone too far, you start seeing evidence left such as cuprous oxide and after that pitting and irremovable (without acid) types of verdigris that are at least partially mineralized.

Interesting, thanks Tim!