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<p>[QUOTE=&quot;lehmansterms, post: 2785407, member: 80804&quot;]The explanation on the <a href="http://www.classicalcoins.com/flans1.html" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.classicalcoins.com/flans1.html" rel="nofollow">http://www.classicalcoins.com/flans1.html</a> website is the result of years of discussion and input from metallurgists and metal workers. It works just fine to explain everything I have ever observed on &quot;centration dimpled&quot; coins. There is no reason that it had to produce perfectly round flans - we can tell from the tool-marks around the edges and how they show evidence of &quot;chatter&quot; that the blade was &quot;riding&quot; around the edge and not cutting an edge in the manner of a solidly fixed tool on a modern turret-lathe. You can see where the pontils have been reduced, but not, necessarily, trimmed completely away, although the tool marks can be seen to go up and over the pontils.</p><p><br /></p><p>Both sides needed to be faced as it was necessary to remove the slaggy crust and/or any sand or other debris which might be incorporated into the surface of the cooling metal after pouring.&nbsp; That nice, smooth flan-surface produced when any impurities and/or brittle, hardened metal had been planed away on those large flans would be ideal for striking with the least damage to the dies. It probably required a huge hammer - or possibly a drop-hammer - to strike the features onto those those 40+mm drachmae.</p><p><br /></p><p>The whole &quot;theory&quot; of hot striking seems likely to originate from an expatiation of someone&#039;s observation of a blacksmith working red-hot (softened) iron or steel. Coin alloys do not have that same broad range of temperature between &quot;solid&quot; and &quot;liquid&quot;. In iron, it&#039;s several hundred degrees, in silver or copper it&#039;s only a few degrees. It would have been impossible with the furnace technology available to heat flans to that narrow temperature-range and maintain it without melting them or allowing them to cool. Even if it were possible to heat-soften them in bulk and maintain that temperature range in the furnace, in the time it would take to grab one with pincers and transfer it to the waiting obverse &quot;trussel&quot;-die it would have cooled enough that any advantage gained by heating would be lost and the metal would be as solid as if it had started out cool.&nbsp; Even if there was some sort of quick &quot;feeder&quot; apparatus to deliver these theoretical heat-softened flans to the die, as soon as they touched the die it would act as a heat-sink and again, they instantly fall below the temperature at which heating might possibly do any good - plus, heating creates fire-scale.</p><p><br /></p><p>That (cast) flans were heated before striking, however, makes sense. They would want to anneal the cast metal to relieve the stressed surfaces created by differential cooling of the flans and soften the metal pre-strike - but there is no reason the flans could not be left to cool completely before striking.&nbsp; In fact, they probably went from the annealing furnace to the &quot;pickling&quot; vat where the surfaces were acid-bleached and cleaned of any fire-scale that the casting or annealing processes may have left behind. Fire scale would have resulted in &quot;strike-through&quot; traces on the surfaces of the coins and would have made the dies wear out more quickly.[/QUOTE]</p><p><br /></p>

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