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Salvete,
Has anyone worked with 'red brass'? This is brass with more copper and less zinc in it than yellow hobby brass. Roman brass was more like red brass than like yellow brass isn't it?
Is red brass stronger or weaker than yellow brass?
Valete,
Jef Pinceel
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And another question:
Matt Amt says on his site that things like helmets and lorica fittings were mostly made out of orichalcum with a zinc content of 15-20%.
Is this indeed the case for most lorica fittings? Are they of a more reddish colour than modern yellow hobby brass? I've seen a few original hinges but most were very yellow...
Can someone help me with this?
Thanks in advance,
Kind regards,
Jef Pinceel
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Hi Jef,
I've never worked with red brass so can't really answer your first questions directly, however the data I've found gives tensile strengths of red brass (UNS C34000, 85:15 Cu:Zn) vs. half-hard yellow brass (UNS C26000 70:30 Cu:Zn) as 40000psi and 62000psi, respectively. So it would seem that red brass is rather softer than yellow brass.
As for your second question, it has been my impression that original military objects such as balteus plates, buckles, pendants and segmentata hinges do indeed seem to be made of orichalcum that isn't significantly different in appearance from modern yellow brass. I have removed at least a tiny spot of the patina in an inconspicuous area on all my artifacts now to reveal the actual metal, and it all looks just like the yellow brass I use for my replicas to me.
Red brass seems to be used mostly for plumbing pipe- one of the largest manufacturers of copper and brass in North America only offers red brass as pipe- and from what I recall when I've seen it in the past is that it is more of a gold color- clearly different than yellow brass. So, my thinking is that modern yellow brass is indeed the best material to use.
Matt
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Quote:Should one bother to use this material for some items and yellow brass for others or isn't it worthwhile?
Well like I said, all the original pieces I have in my collection don't look significantly different from regular 70:30 yellow brass, so I don't see any reason to go to the trouble and expense to get brass that has a slightly lower zinc content unless your intent is to go for metalurgical accuracy over all else.
It seems to me that a variance of 5% among the sample of metal tested isn't exactly small, so makes me wonder just how strict the 'recipe' for making brass really was anyway. It must also be borne in mind that if the sample population that resulted in the 15-20% zinc-content data was small, it may not be reasonable to take it as anything other than a very general idea of the composition of orichalcum.
I have a couple of orichalcum coins (a Dupondius and a Sestertius) that, judging by their colors, appear to have quite different zinc contents; one is quite yellow- moreso than modern yellow brass- and one that is rather red-gold, so I'd bet their zinc contents are outside the 15-20% range.
Mike- do you know how many pieces were tested to yield the 15-20% zinc range you mention?
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