Montefortinos: Brass or Bronze?

[Poftim]

Hello,

I'm really confused right now if Montefortino's were brass or bronze (or both?) Some websites say they're Brass, and some say they're Bronze. However, it seems like all the originals that I've seen were said t obe Bronze and all the reproductions are brass. Any help would be appreciated.

EDIT: I even found one that was copper here

[Spiridonov Alexander]

I think, that it made from bronze.

[Peroni]

If you read the description of the helmet in the database closely it does state that it is copper 'alloy' which can be either brass (copper with zinc) or bronze (copper with tin).

[LUCIUS ALFENUS AVITIANUS]

Generally and in a new condition, bronze have a redish tone, and brass is very close to the gold color (roman calls it oricalchum).

Problem is when the copper of these alloys oxidizes, make both alloys to get the same green colour. so, many times we can't with the naked eye to see what alloy is. Metalographics analysis are needed.

Some helmets are well preserved (at river depositions, etc...) and have his original colour.

That seems to be brass :

[url:1tztqmq6]http://romancoins.info/g2005%20(4).jpg[/url]

That, bronze:

[url:1tztqmq6]http://romancoins.info/London%20(24).JPG[/url]

But we know romans can make alloys of copper, zinc and tin, that it's not brass nor bronze. Copper without alloy can't be used: it's very soft.

Conclusion: I think roman helmets were maded of both materials. I can't speak what's more common: we need for that the analysis of a good number of exemplars.

[Gaius Decius Aquilius]

From one of the only sources I know of, Metallurgy In Archeology, R.F. Tylecote, 1962, there seems to be a rule-of-thumb generalization. This seems to apply to the study area, being England. Roman "copper alloy" contains zinc, obtained by adding Calimine oar to the smelting process. Pre-Roman "copper alloy" does not have it. The zinc content will run from 1% to as much as 30%, with 9% to 18% being the most common. The rule of thumb is that if it has zinc it is brass. If it does not it is bronze. Late Bronze age artifacts can sometimes have a high lead content, as much as 30%. Early bronze age artifacts contain significant amounts of arsenic and antimony or both.

Tylcote works on the premise that the zinc production method was introduced by the Romans, and that method then spread to the rest of Britain. The original suggestion based on an incomplete study suggested the area around Hadrian's Wall as the originating area. What is missing is any data on the metallurgy on the continent prior to the Invasion. How this relates to the Montefortino is problematic, since it has a fairly long life span and wide distribution. I suspect that the earlier ones are "Bronze" and the later ones are "Brass". It is possible the zinc composition, with a small amount of lead, would be better suited for the "mass production" Montefortinos attributed to the Marian reforms. This alloy being easier to work. This is pure guesswork, however. What is "Bronze" and what is "Brass" has a lot of if-and-or-but exceptions and it is much less of a headache to call things copper alloy.

Modern casting alloys include "Ancient Bronze", (no zinc), "Yellow Brass" (contains zinc and 1% lead), "Yellow Bronze" (4% zinc). The other components are not listed. I am using "Ancient Bronze for casting Greek shield fittings and Yellow Bronze for Roman stuff. That is when I get my casting equipment uncovered. I am sanding down a Greek shield and the amount of dust is overwhelming, and I dont want it to get into any of the casting gear. Finishing the shield is what I should be doing right now instead of posting this, but...

Gaius Decius Aquilius
(Ralph Izard)

[arklore70]

Bishop and Coulston also state the helmets were made of a copper alloy on page 65 of their second edition.

IMHO, that would imply that currently, both brass and bronze are correct.

Now, here is the kicker of a question I have,..which materiel has better protective qualities?

V/r
Mike

[Poftim]

I believe this is how it works, arklore70: (I'm gonna say all this is in a generality)

Bronze is harder than Brass. Therefore: Brass will have a tendency to bend, while Bronze will have a tendency to break. However, it's easier to make Brass bend than it is to make Bronze break.

Did that make any sense at all?

[Matthew Amt]

As I understand it, the use of brass or orichalcum (copper/zinc) roughly coincides with the reign of Augustus, but I haven't seen any studies done on this so it may have come into use earlier than that. Basically I assume that Republican helmets are bronze while later ones are brass, but naturally there's going to be some overlap.

"Copper alloy", as others have pointed out, is a weasel-word used for any artifact that hasn't been analyzed to reveal its content. Most older books just say "bronze", though I've seen some that simply use "brass" for anything. Of course, some artifacts have both zinc and tin, apparently from objects being melted down for recycling. And yes, any copper alloy can also have lead, though that was mostly added to cast items. So "copper alloy" is a very *safe* weasel word! (Eagles may soar, but weasels don't get sucked into jet engines!)

Hardness depends greatly on the alloy. Higher zinc or tin content makes the metal harder. Bronze with 12 to 15 percent tin can be harder than wrought iron, particularly if it is work-hardened, while a 5 percent bronze or brass would be quite malleable. It's probably pointless to try to decide just which metal is "best" or "easier to work" since there are so many variables, including the preferences and skills of the metalworker! I don't think ease of production was a large factor for choosing a particular metal.

That help? Valete,

Matthew