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To: David Mead <david_mead@sil.org>, an-lang@anu.edu.au<br>
Subject: Re: [An-lang] copper alloys (brass, bronze)<br><br>
As an archaeologist, I can offer some responses to your questions.
I hope these might be useful.<br><br>
William Ayres<br><br>
Your questions were:<br><br>
1. Given that we're talking about rural Indonesia, is there a
"default" expectation, e.g. would you expect a tray to be
brass, or a gong to be bronze? How could I find out if my
assumptions were indeed correct?<br><br>
It would be difficult to make such a distinction based on just
macroscopic characteristics. Many complex copper-alloy shapes that
have been tooled or machined (like a screw), as opposed to just cast,
tend to be brass, especially historic ones. This is because brass is
somewhat stronger, but you can't tell just by looking at the metal
surface. This would require metallurgical analysis. Today,
while the distinction of bronze being alloys of copper and tin (say 12%
tin) and brass as alloys of copper and zinc (10%) would be common in
industry and many variants of the alloys exist, prehistoric metal workers
tended to produce copper alloys with combinations, at low percentages, of
several metals (primarily tin, but also lead, arsenic, and perhaps
zinc). One technical definition of bronze is that it contains no
zinc.<br><br>
Most archaeological *cast* specimens of the early copper alloys in
Southeast Asia are bronze, not brass, and the term "bronze" is
widely used to group all copper alloy artifacts (including those that
contain some zinc) because one can't tell what it is unless a
metallurgical assay is performed. <br><br>
<br>
2. What were the centers for producing such metal objects, and how
might they have wended their way into, say, interior Sulawesi?<br><br>
Coastal trade centers in Island Southeast Asia would be the main conduit
of metal goods coming into the islands early on, with mainland SE Asian
mines being the original source of the materials and some finished
goods. Local, coastal re-working of copper alloy metals and metal
goods probably began soon after these were introduced. The interior
people acquired the metal objects through trade. As far as I know,
no metalworking sites in the island interior have been found, and small
villages in the mountainous interior would probably not have supported a
metalworking specialist.<br><br>
<br>
3. Along with this, how old are such objects likely to be?
<br><br>
The earliest copper alloys--with tin, lead, arsenic, and perhaps some
zinc--in Southeast Asia (in the mainland) are approximately 2200-2000
BC. They became widespread in the mainland by 1500 BC and
considerably later than that in the islands. <br><br>
<br>
4. Can you point me to any sources where I could learn more about
metallurgy in insular SE Asia?<br><br>
Vince Piggot at the University of Pennslyvania Department of Anthropology
is well-known for his archaeological research on the origins of early
copper alloys in Southeast Asia. You might look at Charles Higham's
volume, The Bronze Age of Southeast Asia, for a synthesis on the bronze
age archaeology of Southeast Asia. Peter Bellwood's
Prehistory of the Indo-Malaysian Archipelago (1997) is specifically on
insular Southeast Asia.<br><br>
William Ayres<br><br>
<br>
At 09:34 PM 10/18/2007, David Mead wrote:<br>
<blockquote type=cite class=cite cite="">Hi,<br><br>
When doing dictionary work on the island of Sulawesi, I've been befuddled
whether to describe certain metal objects as made of "brass"
(copper+zinc alloy) or of "bronze".(copper+tin alloy).
These metal objects include:<br><br>
<x-tab> </x-tab>axe
heads<br>
<x-tab> </x-tab>bells
<br>
<x-tab> </x-tab>gongs<br>
<x-tab> </x-tab>bowls
(sometimes having a foot)<br>
<x-tab> </x-tab>trays<br>
<x-tab> </x-tab>box for
betel-nut ingredients <br>
<x-tab> </x-tab>finger
rings<br>
<x-tab> </x-tab>ear
ornaments<br>
<x-tab> </x-tab>bracelets
(both thin and thick)<br>
<x-tab> </x-tab>arm
bands<br>
<x-tab> </x-tab>anklets
(both thin and thick)<br>
<x-tab> </x-tab>thin rings
worn above the calf<br>
<x-tab> </x-tab>head
ornaments<br><br>
My understanding is that it is difficult to tell the difference by simple
inspection.
<dl>
<dd><i>Color</i>: brass with a high zinc content is yellowish, but
brasses with a lower zinc content can be the same color as some
bronzes. <br><br>
<dd><i>Weight</i>: brass and bronze have very nearly the same specific
gravity, one is not appreciably heavier than the other<br><br>
<dd><i>Patina</i>: both brass and bronze develop a patina which can be
rubbed off, viz. become shiny in places where they are often
rubbed..
</dl>Complicating the picture is that "lesser grades of bronze can
also have some zinc in the alloy, resulting in properties closer to
brass."<br><br>
In a way, it's just a problem of the English language. Malay uses
<i>kuningan </i>for "yellow brass" (brass with a high zinc
content) but <i>tembaga </i>for darker brasses as well as copper and
bronze. My understanding is that Dutch <i>koper </i>/ <i>koperen
</i>also has about this same range of usage as Malay <i>tembaga </i>--
though it would be good if someone could confirm this for me.<br><br>
So my questions are:<br><br>
1. Given that we're talking about rural Indonesia, is there a
"default" expectation, e.g. would you expect a tray to be
brass, or a gong to be bronze? How could I find out if my
assumptions were indeed correct?<br><br>
2. What were the centers for producing such metal objects, and how
might they have wended their way into, say, interior Sulawesi?<br><br>
3. Along with this, how old are such objects likely to be?
<br><br>
4. Can you point me to any sources where I could learn more about
metallurgy in insular SE Asia?<br><br>
Thanks much,<br><br>
David Mead<br><br>
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