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Brass / Bronze
#16
Quote:Yes, but those don't seem to be available in sheet form. There are certainly uses for bronze rod now and then, but most of us armor junkies are mainly interested in sheet metal!
It looks as if it is available in sheet, perhaps simply not from that particular supplier:

http://www.nbmmetals.com/c52400_specs.html
Manny Garcia
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#17
Quote:Does anyone know the composition of the alloys used for bullet and shell casings? These alloys can be streched a lot without breaking or tearing. It might be that the romans could make comparable alloys.

http://www.nbmmetals.com/c26000_detail.html
Manny Garcia
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#18
Quote:Hooo-eeee, bronze rod SIX INCHES in diameter!! That'd make a dandy battering ram!
I was thinking of points for trebuchet-launched plumbatae...
Manny Garcia
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#19
Here's a foreign wholesaler who supplies C52400 sheets in thicknesses up 2.0 mm, so there are probably retail outlets out there somewhere that stock it.

http://www.alibaba.com/product-gs/21622 ... C5240.html
Manny Garcia
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#20
Quote:
Matthew Amt:286em9ql Wrote:Yes, but those don't seem to be available in sheet form. There are certainly uses for bronze rod now and then, but most of us armor junkies are mainly interested in sheet metal!
It looks as if it is available in sheet, perhaps simply not from that particular supplier:

http://www.nbmmetals.com/c52400_specs.html

Huh, cool! Still doesn't say whether it can be made wider than 12 inches, but it's something. I honestly haven't done much heavy searching lately--even if you do find something usable, the costs are bad! And I was lucky enough to get a few pieces of 18-gauge bronze of some sort as scrap recently, so I'm set for my next couple years of projects. (A couple cuirasses, half a dozen helmets, 2 or 3 shields, etc.)

Doc, I suspect there was very little trial and error still being done by the Roman era. Copper alloys had been in use for 3000 years, after all. Sure, once in a while a new alloy appeared, but they had plenty of experience with the basic processes already. Incidentally, one tricky part is that the *boiling* point of tin and zinc are *below* the melting point of copper. So you have to melt the copper first, then add the tin or zinc and very quickly do your casting, before the stuff boils away. (Zinc fumes are very toxic, by the way!) And when you remelt brass or bronze for reuse, you lose some of the tin or zinc each time. So it's tricky, but the ancients were very familiar with these problems. To the point where modern craftsmen often have a hard time duplicating some ancient objects or techniques! Those guys were good.

Valete,

Matthew
Matthew Amt (Quintus)
Legio XX, USA
<a class="postlink" href="http://www.larp.com/legioxx/">http://www.larp.com/legioxx/
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#21
Quote:If Roman yellow bronze or brass is anything to go on here are links to a picture of the Trimontium cavary sport helmet. The original and my reproduction which I made in modern 70/30 brass.

http://www.northumberland-computers.com ... oman10.jpg

http://www.northumberland-computers.com ... roman7.jpg

Hmmm, that looks like the original on your table Brian, or did you just do another fine job? Confusedhock: :lol:

As for getting bronze, I was quoted over £1100 for a 1" x 1' , 1' sheet 2 years ago, the thinner sheet was cheaper then though, but was only available on order.
Wish I had the money to buy it back then. :roll:
Visne partem mei capere? Comminus agamus! * Me semper rogo, Quid faceret Iulius Caesar? * Confidence is a good thing! Overconfidence is too much of a good thing.
[b]Legio XIIII GMV. (Q. Magivs)RMRS Remember Atuatuca! Vengence will be ours!
Titus Flavius Germanus
Batavian Coh I
Byron Angel
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#22
Matt,

I agree that they had experience. However, what I was trying to point out was that their experience came from trial and error not because they knew "chemistry" in the manner in which it is known today. Anyone who is not a chemist can mix stuff together and observe something interesting that may be useful. Then, if necessary, the steps are repeated hopefully with the same measurments and results.

Materials do not just "boil away". There are considerations in a liquid mixture such as partial vapor pressures of a relative concentration of each metal. Liquid solutions based on their realtive quanitites and through molecular interactions can change how they behave. Two compounds can in fact behave nearly as one.
They just said "take a handful of this and mix it with a handful of that or they would have used some balance to measure a mass for reproducibility.

I am not taking anything away from the Romans. I agree they were good and knew their stuff. However, I would also like to point out that even if the knowledge of working with copper was known for eons, it does not necessarily mean that the Romans were privy to all the techniques especially in their begining and did not have to experiment. In human history, wether something is known or not, most people will reinvent the wheel.

To make the alloy, one should melt zinc in one pot and copper in another. Then add the zinc to the copper. In adding you must mix or agitate the solution for maximum contact between the two substance. The contact leads to cetain molecular interactions and bonds that yield the alloy. Adding to liquified substances automatically increase surface area and contact. Melting Copper and then throwing solid zinc into it causes a delayed reaction since the zinc has to melt. Even thought it will melt, time has to pass. As something slowly melts the little that is extruded from the solid each time is insignficant and it is this that causes the majority of low boiling substance to vanish.
"You have to laugh at life or else what are you going to laugh at?" (Joseph Rosen)


Paolo
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#23
Quote:Materials do not just "boil away".

Well, I don't know chemistry, but the melting point of copper is 1084 degrees C., while the boiling point of zinc is only 907 degrees (assuming Wikipedia got it right!). People who have done brass casting have told me that the zinc content drops each time a piece of brass is remelted, so it's going somewhere. I also know that an armorer was killed a couple years ago by zinc fumes.

Quote:I am not taking anything away from the Romans. I agree they were good and knew their stuff. However, I would also like to point out that even if the knowledge of working with copper was known for eons, it does not necessarily mean that the Romans were privy to all the techniques especially in their begining and did not have to experiment.

Ah, you're seeing civilizations or cultures as distinct events in time, with beginnings and ends. But in reality the first Romans were not people dropped onto the seven hills with no arts or crafts, they were simply the same folks who had lived there for many generations, with a continuous database of knowledge in metallurgy and other crafts. They didn't have to relearn anything.

Quote:To make the alloy, one should melt zinc in one pot and copper in another. Then add the zinc to the copper.

That's not how I've learned it. Mind you, the brass casting I've seen was done simply by melting scrap, no mixing of metals was needed. But I've been watching Neil Burridge, Jeroen Zuiderwijk, and other people rediscover ancient bronze casting over the last few years via the Bronze Age Center, and they seem to know what they're talking about. There is never any mention of 2 pots of molten metal. They melt the copper in a crucible, then add pieces of tin.

http://www.bronze-age-craft.com/
http://1501bc.com/index_en.html
http://s8.invisionfree.com/Bronze_Age_Center/index.php ?

I have also read (though I don't recall where) that the Romans used zinc oxide for their zinc. Don't know anything about how it occurs in nature or is refined, though.

Well, it's late and my brain is shutting down! Valete,

Matthew
Matthew Amt (Quintus)
Legio XX, USA
<a class="postlink" href="http://www.larp.com/legioxx/">http://www.larp.com/legioxx/
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#24
Yes,

The zinc content will drop if you heat up brass to use it in casting. However, I was not discussing heating up brass, I was discussing the formation of the alloy. I never said that zinc will not evaporate. All I said was when mixing two liquids other things go on that give rise to the compositions people obeserve. "Boiling away" is one thing, but there are others.

I also do not care for the characterization that you deemed necessary to explain to me the origin of the Roman civilzation by attempting to enlighten me that the Romans were not dropped onto the seven hills. I was born in Italy and I can assure you that I do not need an anthropology lesson. All people have lived in a particular place in time for generations. However, in historical contexts we do give cultures and civilazation finite times. The birth of Rome 753 BC the fall of rome 5th centruy AD. Furthermore, I did not say that the Romans had to re-learn anything. I merely pointed out that it is part of human nature to re-invent the wheel many times through no fault of anyone in particular.

Again, I never said that the Romans or ancients made alloys in the way that I described. I was suggesting an efficient way that such a mixture could be obtained. Unless there is someone out there with a time machine to prove otherwise, most reasonable applications (such as I described) are possible.
"You have to laugh at life or else what are you going to laugh at?" (Joseph Rosen)


Paolo
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#25
Quote:I also do not care for the characterization that you deemed necessary to explain to me the origin of the Roman civilzation by attempting to enlighten me that the Romans were not dropped onto the seven hills. I was born in Italy and I can assure you that I do not need an anthropology lesson. All people have lived in a particular place in time for generations. However, in historical contexts we do give cultures and civilazation finite times. The birth of Rome 753 BC the fall of rome 5th centruy AD.

Sorry, no offense intended! Sure, we like to apply nice labels and dates, and we like to put things in neat boxes. I just got the impression that you were seeing the Roman culture as kind of set apart from its historical context--other people have thought that way before. Mea culpa.

Quote:Again, I never said that the Romans or ancients made alloys in the way that I described. I was suggesting an efficient way that such a mixture could be obtained. Unless there is someone out there with a time machine to prove otherwise, most reasonable applications (such as I described) are possible.

Fair enough. I think there are some references to metallurgy in Roman literature that would probably be a big help, here, but unfortunately I don't know what they are offhand. Pliny is probably a good place to start for things like that, at a guess.

Vale,

Matthew
Matthew Amt (Quintus)
Legio XX, USA
<a class="postlink" href="http://www.larp.com/legioxx/">http://www.larp.com/legioxx/
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#26
Matt,

I appreciate your candor. As a matter of fact I respect you and the things you say. I apologize for being rash.
"You have to laugh at life or else what are you going to laugh at?" (Joseph Rosen)


Paolo
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#27
Reading Plinius' account on metalworking is indeed a very good idea.
Jef Pinceel
a.k.a.
Marcvs Mvmmivs Falco

LEG XI CPF vzw
>Q SER FEST
www.LEGIOXI.be
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