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<p>[QUOTE=&quot;robinjojo, post: 8186800, member: 110226&quot;]Here&#039;s another coin that has been treated for persistent bronze disease on the reverse.&nbsp; It&#039;s been a battle, and the results are not pretty.</p><p><br /></p><p>This is a bronze dirhem, Mardin, AE 28, of Najm al-Din Alpi, AH 547-572 (1152-1176), Spengler-Sayles type 27.</p><p><br /></p><p>The reverse appears to have had some metal loss in one spot when the coin was struck or when the counterstamp on the neck was applied.&nbsp; The flan&#039;s metal must have been poorly refined or annealed. There is a clear break line connected to an area of metal that must of chipped off.&nbsp; This area became filled with oxide deposits and moisture, creating the bronze disease.&nbsp; The BD spread to other parts of the reverse towards the left edge.</p><p><br /></p><p>I had to do a few stints for this coin in distilled water and sodium sesquicarbonate.&nbsp; At times, when the coin was removed, the BD appeared to be gone, only to reappear.&nbsp; Finally, I think it is under control, but time will tell if this is so.</p><p><br /></p><p>The patina on the obverse is gone, leaving rough surfaces, but at least the coin is still identifiable, and the counterstamps on the obverse are still visible.</p><p><br /></p><p>10.88 grams</p><p><br /></p><p>[ATTACH=full]1432347[/ATTACH][/QUOTE]</p><p><br /></p>

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