Numismatics on acid

[Per D]

Apologies for the sophomoric pun.

Attacking some stubborn deposits on this follis with diluted phosphoric acid and a Q-tip was not only effective, but also resulted in (partial) restoring of the silvering, presumably through a process of surface depletion.

I won’t experiment on other coins, but I wonder if anyone has had a similar experience.

/Per

[Heliodromus]

Do you have a "before" photo for comparison ?

[Per D]

I forgot to take one myself, but here's the seller's photo.

[Victor]

the silvering was there always, just covered. Whenever you see these coins with similar green, it usually means silvering; though it doesn't mean that the surfaces will turn out nicely.

[Per D]

Thanks for your input, appreciated as always.

Do you have any ideas what would be a better/safer way to clean surfaces like this?

/Per

[Victor]

You can always use diluted lemon juice, I have a bag of powdered citric acid, so I can mix it up. You have to be very careful when using acids (and bases) to clean coins-- it's easy to mess up a coin.

[Per D]

Indeed!