Has the presence of horn silver ever prevent you from buying a coin you otherwise thought was attractive? Is horn silver aggressive in nature (like verdigris on copper or bronze) where is progressively gets worse unless treated? I’ve used Verdicare for verdigris conservation, wondering if any options availably to conserve horn silver plagued coins. Post your examples here’s a few examples I have found while browsing. First example Looks a bit like @Al Kowsky ’s example posted in this thread… minimal horn silver https://www.cointalk.com/threads/horn-silver-or-not.331298/
I have a few coins with horn silver. I admit I am not a fan of it but it isn't like Bronze Disease where it spreads easily. I won't say no to a coin with it though so long as the price reflects it. There have been posts on here from some who have been able to remove it, but it's a lot of chemicals and is fairly involved from what I remember.
The horn silver is mostly out of the way, and personally I even think it kind of adds to the coin’s charm. The way its positioned in front of Athena makes it look like she is summoning storm clouds (makes sense because of the thunderbolt she is holding). Menander I, Indo-Greek Kingdom AR drachm Obv: BAΣIΛEΩΣ ΣΩTHPOΣ MENANΔPOY, helmeted, draped bust right Rev: "Maharajasa tratarasa / menamdrasa" in Kharoshthi, Athena Alkidemos standing left seen from behind, holding shield on left arm, hurling thunderbolt in right hand, PA monogram to right Mint: (Unknown mint in Bactria) Date: 160-145 BC Ref: BMC 8
I am no expert at all in cleaning coins. Silver, even though nobler than copper, when exposed to sulfurous elements can build a silver sulphide coating on some parts, but also on the whole coin. Silver sulphide has a dark-brown to black color. Removing horn silver is quite complicated; in my opinion, if the silver contents is good it should be treated professionally. The second coin shared (Tiberius) in the OP seems to be damaged by a treatment that wasn’t professional and by removing the horn silver it exposed a corroded surface. I have this tetradrachm almost all covered in horn silver; one can see silver shining through on both sides, but I just leave it as is, it gives character to the coin and it protects the surface below Cilicia, Tarsus, ca. 1 BC - 10 AD, RPC suggest ca. 5 AD 24 x 26 mm, 14.838 g RPC I 4004; Prieur 748; SNG BN 1388; SNG Levante 988; Ob.: ΣΕΒΑΣΤΟΥ ΚΑΙΣΑΡΟΣ laureate head right Rev.: MHTPO(ΠOΛ)EO(Σ) Tyche of Tarsus seated right on rock, holding palm frond; below, half-length figure of river-god Kydnos swimming right; TAP monogram (for Tarsus) in right field
This must be one of my more dramatic restoration jobs: Or, alternatively, this one: Over the past couple of years, I've cleaned about 300 ancient silver coins, usually brought to me by metal detectorists or collectors. Most of them are affected by horn silver (AgCl) which is relatively easy to remove (I've posted many walk-throughs on the topic, see my post history or search on horn silver). Iron deposits are way more difficult.
I find horn silver pretty stable. Once a coin is removed from the environmental factors that created the horn silver, I have found little change and no real growth, although I imagine humidity might cause some further oxidation over a long period of time. Remember, it took centuries, even thousands of years for that thick black layer to form on a silver coin. Yes, I have some ancients that are encrusted with horn silver, looking pretty much they way they did coming out of the ground. Here are a couple of examples:
Can you share a coin(s) you are currently considering with horn silver? Al’s example is fantastic, regardless of a small horn silver patch
