Recent cleans

Not really recent, but a very successful clean!
Diva Faustina in a carpentum. Large (wooden) images of the deified emperors and empresses were present at festivities and games. So this is not a funeral procession, but a memento of the greatness of the person.
RIC 1113

 

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hotwheelsearl, do you mind sharing your "forumla"? Amount, dilution, time, etc?

I am a mechanical cleaning guy who avoids chemical, but as you note there are times/coins where there is no option.

So far my only chemicals (other than for BD treatment) have been citric acid or acetic acid for cleaning black gunk off silver. But I do have a growing "frustration bin" of crusty AEs.....

SC

 

Happy to share!

I do not understand any of the chemistry, but in my experience, it's a rather color-coded system that works for me.

Bronze and silver
Green, Black, Brown, Sand = sodium hydroxide
Blue = acetic acid
Rust = sodium thiosulfate
-- for silver, black horn silver is also removed by thiosulfate

In general, rock-like mineral encrustations slough right off with hydroxide. Vinegar and thiosulfate don't do much at all for those.
Basically, for mineral encrustations that you COULD, but DONT WANT TO mechanically clean, hydroxide speeds up the process a thousand fold.

As for dilutions and times - I'm not very scientific. I throw some powder/crystals in a jar and leave it overnight. If it's not enough, I'll do another night.