I don't usually mess with coins, but this scyphate Himyarite coin had blotchy black patination with exposed silver, which made it spotty and ugly to my eyes. So I covered a bowl with aluminium foil, then poured boiling water and baking soda on the coin in the bowl, and allowed it to cool down. Gotta say it looks much better and 'uniform'. But I still didn't scrap the spots on the corner of the obverse and in the reverse, as it's cup-shaped I could easily damage it in the process.
Cleaning is okay for ones you want to keep. I just cleaned a very tiny spot of PVC off an otherwise perfect 1963 Washington quarter last night, simply to save the coin. Now its a beautiful "junk" silver coin. Was going to send to PCGS until found the spot. Used Acetone. I also carefully clean error coins but only if it is a distractingly ugly area on a good error.
I replaced my NewStyle Trident with a better example which I had to clean up. Sold the old and in with the new. All I have to do now is attribution....I think the obverse is not in Thompson's plates-maybe in Gaziantep or Demetrios l Hoard plates-we shall see eventually. The old; Athens New Style Tetradrachm 147/6 BC SOLD Obs : Athena Parthenos right in tri-form helmet 16.74 gm 34mm Thompson issue 18 Thompson catalogue : Obs 127 : Rev NEW Rev : ΑΘΕ ethnic Owl standing on overturned panathenaic amphora below control mark ΠΡΟ 2 magistrates : ΑΔΕΙ ΗΛΙΟ RF symbol : Trident Head All within a surrounding olive wreath SOLD And in with the new after a good clean up! Now that's much better.
It's an ancient, no problem, its only the newbies you have to worry about cleaning! Thanks for the post good luck.
FYI, cleaning is completely OK for any ancient coin, as long as one goes about it carefully and in the right way. In fact, it's generally believed that all ancient coins have been cleaned, except for the ones that are left the way they looked when they came out of the ground -- which is where all ancient coins come from. (There's zero evidence that any ancient coin exists that has been above ground since it was issued.) The standards for U.S. coins regarding cleaning are entirely different.
I never thought about using the aluminum trick on silver. a “standard” procedure for horn silver seems to be sodium thiosulfate. Only problem is that tends to lead to a rather dull gray surface. One can then immerse into a sodium hydroxide solution for a few minutes to potentially bring back the luster, though I haven’t tried that to be sure
"Beauty is in the eye of the beholder" always applies, so just for what it's worth I like your original tetradrachm better than the replacement.
Using acetone is not considered "harsh" cleaning unless you apply it with a scouring pad. Let's see the coin.
