advice how to clean an roman antoninianus

[karaya75]

i have this coin full off encrustations, very hard to remove. how can i remove it?

thank you

[Ron C2]

do you know the emperor and silver level?  Is it silver or billon? 

If it's indeed reasonable purity silver, have you tried some lemon juice on a Q-tip?

[karaya75]

hello

 its a gordianos 3

[nikopolis1]

Get some formic acid.Dilute to around 10-20 % .The acid will dissolve this incrustations.But monitor the coin,1-2 hrs and should be ready.

[SC]

Personally, I would go gentler and use Ron's lemon juice, or vinegar, applied via q-tip.  This may soften the green to the point that a fingernail or bamboo skewer will remove some.

I wouldn't go harsher until that technique, or even leaving drops of lemon juice or vinegar on the green for a few minutes, had proved to not work.

SC

[B-Chicago]

me and my harshness never uses cotton on silver but it's all a matter of opinion anyway

my first approach would be to soak it - in DW -  for a long time and see how that materializes with short lemon juice baths in between

that should really put a dent in that gunk

[Ron C2]

I'm rather hoping to OP didn't just fly in to get advice and vanish.  It's much more polite when some feedback comes after he tries a few things.