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<p>[QUOTE="Roerbakmix, post: 3715677, member: 100731"]<font size="4">I'm currently studying several archeological and numismatical articles on the restoration of ancient silver. There seems to be no consensus article on horn silver, which I aim to write. </font></p><p><font size="4"><br /></font></p><p><font size="4">Sodium thiosulphate can be bought at some drug stores. It's relatively cheap: I bought 200 gram for €4,00. On the average coin with horn silver, I use approx. 2-3 gram. </font></p><p><font size="4"><br /></font></p><p><font size="4">I will post the draft version of my article probably this month. </font></p><p><font size="4"><br /></font></p><p><font size="4">A general advice to [USER=91240]@SeptimusT[/USER]: I would not clean the coin mechanically, but start chemically. Please note that every kind of cleaning will alter the patina of the coin: underneath the horn silver, there will be no patina. Sodium thiosulphate however reacts with the AgCl creating Na3[Ag(S2O3)2] and NaCl. The Na3[Ag(S2O3)2] has a nice, dark appearance which is common to 'cabinet toning' (which makes me wonder about artificial patina in general). </font></p><p><font size="4"><br /></font></p><p><font size="4">In my opinion, although I prefer to see the coin in hand, you can safely start with sodium thiosulphate. </font>[/QUOTE]</p><p><br /></p>
[QUOTE="Roerbakmix, post: 3715677, member: 100731"][SIZE=4]I'm currently studying several archeological and numismatical articles on the restoration of ancient silver. There seems to be no consensus article on horn silver, which I aim to write. Sodium thiosulphate can be bought at some drug stores. It's relatively cheap: I bought 200 gram for €4,00. On the average coin with horn silver, I use approx. 2-3 gram. I will post the draft version of my article probably this month. A general advice to [USER=91240]@SeptimusT[/USER]: I would not clean the coin mechanically, but start chemically. Please note that every kind of cleaning will alter the patina of the coin: underneath the horn silver, there will be no patina. Sodium thiosulphate however reacts with the AgCl creating Na3[Ag(S2O3)2] and NaCl. The Na3[Ag(S2O3)2] has a nice, dark appearance which is common to 'cabinet toning' (which makes me wonder about artificial patina in general). In my opinion, although I prefer to see the coin in hand, you can safely start with sodium thiosulphate. [/SIZE][/QUOTE]
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