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01-30-2005, 09:29 AM

Avete! For all those metallurgists out there, a question. If I were to make a helmet, breastplate, etc., out of bronze, what would the most authentic chemical breakdown be? (Time period 1st-2nd C. AD if that makes any diffference.) Many metal supply stores carry silicon bronze, but I know this is a relatively modern version of the ancient metal. McMaster Carr www.mcmaster.com/ offers many, many different bronzes (type "bronze" into the search window). Out of what is choices McMaster Carr offers here, what would the most accurate choice(s)? 
 
Thanks in advance for any help! 
 
Darius

mcbishop · 01-30-2005, 01:43 PM

Part of the problem here is the scarcity of quantitative analyses of helmets that have been undertaken over the years (perhaps understandably; curators and collectors are reluctant to have chunks taken out of their artefacts): I couldn't lay my hands on any during a quick search through the catalogues to which I have access (Robinson, Waurick, Klumbach, the various Guttmann tomes), but the Theilenhofen 'eagle' helmet was assayed at Cu 75-80%, Zn 15-20%, Sn 4%, Pb traces (Klumbach and Wamser 1977), whilst the Worthing helmet was Cu 81%, Zn 12.5%, Sn 5.9% (Roes and Vollgraff 1955, 301 n.3) but you could hardly call these two brass helmets as representative. Many of the best-known helmets have never been tested, the descriptions 'bronze' or 'brass' largely resting on examination with the Mk I eyeball. 
 
In the rare cases where analysis of an ancient copper-alloy artefact exists, you can then look up the modern equivalent on the Anchor Bronze database: 
 
www.anchorbronze.com/ 
 
and not only find out technical details like hardness, how it works, and modern uses, but also the correct name for it (e.g. lorica seg rivets are often made of 'C23000 red brass'). 
 
Mike Bishop

01-31-2005, 10:16 AM

Thanks for the scoop, Dr. Mike! 
 
Darius

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