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<p>[QUOTE="Orielensis, post: 4434058, member: 96898"]It is possible to completely strip a patina, including such extreme encrustations, by letting the coin sit in a solution of sodium hydroxide (lye) for a while. Sodium hydroxide is commonly sold as a drain cleaner. It doesn't attack metal as more aggressive acids do, but it will dissolve about all encrustations. Rinse your coin thoroughly and let it sit in lots of distilled water for a while after giving it this brachial treatment.</p><p><br /></p><p><b>Honest warning 1:</b> Sodium hydroxide is very dangerous to handle. It causes extremely nasty caustic burns when it comes in contact with skin, blindness when it gets into your eyes, and, in the worst case, painful and slow death if you swallow it. It is thus best handled only in a laboratory environment. Always wear at least protective gloves and glasses when even coming only close to such substances.</p><p><br /></p><p><b>Honest warning 2:</b> Sodium hydroxide will strip bronze coins of all patina. You never know what's below the patina, but it surely won't be an immaculately smooth and attractive metal surface. In the best case, you'll get a result like the coin below, which had encrustations similar to yours and spent two days in a weak sodium hydroxide solution. In the worst and more common case, you'll get an unrecognizable slug.</p><p><br /></p><p><b>Honest warning 3</b>: The need to use such cleaning methods and their mostly unsatisfying results were a main reason why I stopped buying uncleaned coins.</p><p><br /></p><p>[ATTACH=full]1109739[/ATTACH]</p><p><font size="3">Constantine II Iunior, Roman Empire, AE4, 335–336 AD, Siscia mint. Obv: CONSTANTINVS IVN NOB C; bust of Constantine II, laureate, cuirassed, r. Rev: GLORIA EXERCITVS; two soldiers, helmeted, draped, cuirassed, standing facing each other, each holding reversed spear in outer hand and resting inner hand on shield; between them, a standard; in exergue, ESIS. 16mm, 1.60g. Ref: RIC VII Siscia 253.</font>[/QUOTE]</p><p><br /></p>
[QUOTE="Orielensis, post: 4434058, member: 96898"]It is possible to completely strip a patina, including such extreme encrustations, by letting the coin sit in a solution of sodium hydroxide (lye) for a while. Sodium hydroxide is commonly sold as a drain cleaner. It doesn't attack metal as more aggressive acids do, but it will dissolve about all encrustations. Rinse your coin thoroughly and let it sit in lots of distilled water for a while after giving it this brachial treatment. [B]Honest warning 1:[/B] Sodium hydroxide is very dangerous to handle. It causes extremely nasty caustic burns when it comes in contact with skin, blindness when it gets into your eyes, and, in the worst case, painful and slow death if you swallow it. It is thus best handled only in a laboratory environment. Always wear at least protective gloves and glasses when even coming only close to such substances. [B]Honest warning 2:[/B] Sodium hydroxide will strip bronze coins of all patina. You never know what's below the patina, but it surely won't be an immaculately smooth and attractive metal surface. In the best case, you'll get a result like the coin below, which had encrustations similar to yours and spent two days in a weak sodium hydroxide solution. In the worst and more common case, you'll get an unrecognizable slug. [B]Honest warning 3[/B]: The need to use such cleaning methods and their mostly unsatisfying results were a main reason why I stopped buying uncleaned coins. [ATTACH=full]1109739[/ATTACH] [SIZE=3]Constantine II Iunior, Roman Empire, AE4, 335–336 AD, Siscia mint. Obv: CONSTANTINVS IVN NOB C; bust of Constantine II, laureate, cuirassed, r. Rev: GLORIA EXERCITVS; two soldiers, helmeted, draped, cuirassed, standing facing each other, each holding reversed spear in outer hand and resting inner hand on shield; between them, a standard; in exergue, ESIS. 16mm, 1.60g. Ref: RIC VII Siscia 253.[/SIZE][/QUOTE]
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