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<p>[QUOTE=&quot;kardinalisimo, post: 103421, member: 118&quot;]It is quite possible that what I have is recently made in India piece. But what&#039;s with words like &quot;trash&quot; and &quot;junk&quot;?</p><p><br /></p><p>Mine bowl attracts slightly to neodymium magnet. So, most likely the copper is mixed with some or all of these - nickel, iron, manganese, cobalt ... together with zinc probably. I doubt it is copper plated iron.</p><p><br /></p><p>It is somewhat true that a lot of copper alloys from India are slightly magnetic. But not all of them. And not sure if only pieces from India have that characteristic.</p><p><br /></p><p>Also, Ancient bronzes were not always alloys of just cooper and tin. Here you can see that other elements were mixed as well:</p><p><a href="http://www.jstor.org/stable/pdf/660717.pdf?acceptTC=true" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.jstor.org/stable/pdf/660717.pdf?acceptTC=true" rel="nofollow">http://www.jstor.org/stable/pdf/660717.pdf?acceptTC=true</a></p><p>Plus, a lot of the copper was smelted ore rather than native copper so impurities of other elements were present.</p><p><br /></p><p>A bit of off topic, electromagnetic filed can be created between non-ferrous metals and neodymium magnet.</p><p>[MEDIA=youtube]VEIYXomRdLY[/MEDIA]</p><p><br /></p><p>Now, back to the trocadero bowl.</p><p>I am not sure how they figured it was Tang Dynasty. Also, spun bronze is very unlikely, so they should have used the term &quot;copper alloy&quot; instead.</p><p>The comparison with the Korean spun bronze is not backed up by anything. Here is the extract from the &quot;Korean Art from The Brooklyn Museum, by Robert J. Moes&quot;</p><p><img src="http://i1301.photobucket.com/albums/ag113/imaginara1/book_zpsgota24fe.jpg" class="bbCodeImage wysiwygImage" alt="" unselectable="on" /></p><p><br /></p><p><br /></p><p>There is only one example of what they called &quot;spun bronze&quot; - a wine bottle from Koryo Dynasty, 13th century. Again, this is most likely not bronze but brass or other copper alloy. If not wrong, this is the same bottle</p><p><a href="https://www.pinterest.com/pin/484559241132832514/" target="_blank" class="externalLink ProxyLink" data-proxy-href="https://www.pinterest.com/pin/484559241132832514/" rel="nofollow">https://www.pinterest.com/pin/484559241132832514/</a></p><p>I wish the author cited the source describing the spinning technique.</p><p>Something that I don&#039;t understand. The bottle was made out of four parts, brazed together ( 3 spun sections and the upper one cast). How did they spin those sections? They are open from both sides, how do you turn them on lathe?</p><p><br /></p><p>The earliest illustration of a lathe is from a well known Egyptian wall relief carved in stone in the tomb of Petosiris dated some 300 BC.</p><p><a href="http://www.turningtools.co.uk/history2/history-turning2.html" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.turningtools.co.uk/history2/history-turning2.html" rel="nofollow">http://www.turningtools.co.uk/history2/history-turning2.html</a></p><p><a href="http://www.stuartking.co.uk/index.php/history-of-the-lathe-part-one-reciprocal-motion/" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.stuartking.co.uk/index.php/history-of-the-lathe-part-one-reciprocal-motion/" rel="nofollow">http://www.stuartking.co.uk/index.php/history-of-the-lathe-part-one-reciprocal-motion/</a></p><p><br /></p><p>Most likely metal spinning existed in Ancient times but I am just not finding any examples and detailed information on the subject.</p><p><br /></p><p>A good read on ancient metal casting in China. Nothing mentioned about spinning.</p><p><a href="http://www.foundryworld.com/uploadfile/201131449329893.pdf" target="_blank" class="externalLink ProxyLink" data-proxy-href="http://www.foundryworld.com/uploadfile/201131449329893.pdf" rel="nofollow">http://www.foundryworld.com/uploadfile/201131449329893.pdf</a></p><p><br /></p><p><br /></p><p>Still investigating <img src="styles/default/xenforo/smilies/smile.png" class="mceSmilie" alt=":)" unselectable="on" />[/QUOTE]</p><p><br /></p>

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