Roman Bronze

[Doc]

Does anyone know or have any studies been conducted to determine the approximate compostion of Roman yellow bronze. :?: Many of the bronze helmets and chainmails exhibit this yellow color.

Most true modern bronzes are reddish in color. ?:

Paolo

[Susanna]

There is a "Copper-Institute" in Germany.

http://www.kupfer-institut.de/front_frame/index.php

There is a lot of information about kinds of bronze etc.

Sorry, as far as I know its only in German.

[mcbishop]

Does anyone know or have any studies been conducted to determine the approximate compostion of Roman yellow bronze. :?: Many of the bronze helmets and chainmails exhibit this yellow color.

Most true modern bronzes are reddish in color. Only brass matches Roman yellow bronze in color. I do not think however, that entire helmets and body armor were made of brass (especially chainmail). :?:

Brass was widely used for military equipment and there were indeed complete helmets made of it. Here is what I wrote about brass in Lorica Segmentata 1 (p.77):

The copper alloy used for most of the fittings (hinged fittings, lobate hinges, tie loops etc) was a type of brass known as orichalcum, the same metal used in brass coinage from the time of Augustus onwards.6 Orichalcum, which is almost golden in appearance (Plates 1 & 4), was a binary alloy of copper (80–85%) and zinc (20–15%) and was quite widely used in military equipment from the 1st to the 3rd centuries AD. As such it closely resembles the modern alloys of ‘low brass’ (CA240) to ‘red brass’ (CA230) (with a Rockwell hardness of between 70 and 65). Since orichalcum was also used in currency, the components of lorica segmentata made from it were, effectively, constructed from bullion. The rivets used to secure the fittings to the iron plates might be of the same composition, but a softer metal was often used, with between 90/10 composition (‘commercial bronze’ (CA220), with Rockwell hardness of 58) and 95/5 (‘gilding metal’, CA210, with a Rockwell hardness of 52),7 which made it easier to secure (peen) the rivets in place. The higher copper content of the rivets also gave them a more coppery colour. No examples of bronze fittings (i.e. a copper/tin alloy) have so far been identified on Corbridge-type cuirasses.8 The different colour characteristics of the various metals means it is often possible to identify uncorroded metals tentatively without the aid of any scientific analysis (the Newstead fittings, for instance, are brass-coloured, although they have never been tested), but such analyses are obviously desirable in the long term.

The CA numbers, technical names, Rockwell hardnesses are accessible online at http://www.anchorbronze.com should you need them. For more work on the various copper alloys used by the Romans (including bronze in the technical sense as an alloy of copper and tin, not just any old copper alloy) see David Dungworth's paper in Internet Archaeology, although you'll have to pay for access).

Mike Bishop

[marsvigilia]

Personally I love Red Brass C230. It has the wonderful property of being workable while glowing hot. Something you can not do with yellow brass. It is so much easier to work when hot.

My primary source for Red Brass is Thunderbird Supply.
http://www.thunderbirdsupply.com/
Phone 1.800.545.7968
FAX: 1.800.557.7968

Red Brass sold in 6 inch widths and various lengths. Also available Red Brass wire.

Does not have the larger gauges, nor sheets over 6 inch width.

Does anyone else have another source?

[Doc]

Dr. Bishop,

Thank you for the clarification. I am aware of the lorica segmentata parts and the other brass itmes you mention.

However, would an entire chainmail garment and scales for plumata or squamata be made of orichulum as well :?:


Thank you

Paolo