What's gunmetal?

I believe it is typically accepted as 90% Cu 10% Zn (a red brass), although I think other compositions claim the name as well (like bronze vs. brass...go figure).

Tim

More than you probably need to know, but.....

Gunmetal can be any number of compositions. As you may already know one old time way of distinguishing copper based metal types would be to name four numbers in sequence with dashes separating them, like 85-5-5-5 or 88-10-0-2 or 88-3-5-4. The four numbers refer to the nominal compositions of the four elements copper, tin, lead and zinc or Cu, Sn, Pb Zn.

Gunmetal has become somewhat a generic term but of course it came from the idea of a metal used to make guns (cannon).

Generally speaking the higher the copper and tin content, the higher the tensile strength. Lead is added for pressure tightness (it "seals' microporosity) and Zinc for improved castability (i.e. flowability and somewhat to reduce gassiness. In the last 25 years there's been an emphasis to reduce lead due to poisoning. Sometimes ingot makers will replace some of the copper or tin with Nickel.

I always felt when someone mentioned "brass" they meant an alloy of copper and zinc, and the item produced was not necessarily made of brass for mechanical strength but more for corrosion or aesthetic appearance. Bronzes are generally where more strength is needed, and "bronzes" can be either the gunmetal series above or nickel bronzes, silicon bronzes, or aluminum bronzes and there are probably a whole lot of other ones but that's all I can think of at the moment.

Hope this helps.

Mark

It's a bronze alloy. It's 9/1 or 10/1 copper/tin as I recall. Originally used to cast cannon barrels, hence the "gunmetal" name.

Don in Ohio

A common tin-bronze. Composition has varied slightly over the centuries but in the US, today, it's the alloy known as C90500: 88% copper, 10% tin, 0% lead, and 2% zinc. This is also designated 88-10-0-2, in common copper-alloy designation.

FWIW, the names "brass" and "bronze" have become all but meaningless in engineering circles, as most bronze contains zinc and some "bronze" has composition that we would call "yellow brass," if we went by composition alone. Common "bronze" brazing rod actually is a standard yellow-brass alloy, for example. And the "brasses" referred to in old railroad- and other engineering texts, meaning the removable plain bearing liners, usually were some type of hard bronze.

Don't think so, 90/10 is red brass, bronze is typically 96/4 Copper/Tin and Gun metal something else!

Steve

in the same sense that "steel", "aluminium", "titanium" or "white metal" are also generic terms?

Steve

There are several alloys. A typical composition would be about 10% tin, 2.25% zinc, 1.5% max lead and the balance copper. Google "gunmetal composition" I bet you get lots of hits. ERS

Pretty much. Steel encompasses everything from mild steel to alloy to highspeed and beyond (but nothing with >2% C or so, i.e., "iron"), while brass or bronze (pretty much interchangable, to the suprise of the average person: "Hey it's yellow - um, brass?" "No, bronze." "-But..." and so on) encompass anything with more than a few percent of alloying elements (less being pretty much copper). Although I've never heard of "aluminum brass" for instance, so some of the old definition holds. If not at least over the three common elements (zinc, lead and tin).

Tim

-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @

No, this is a little different. It's a case of old terms that attempted to distinguish classes of copper alloys, which stopped being useful in that sense over 100 years ago.

I have posted a fair amount of info here on brass and bronze alloys over the years. FWIW, 90% of it comes from the _Metals Handbook_, 9th Edition, published by the American Society for Metals. It contains around 260 pages of detailed data and text on copper and its alloys. It's a great resource, available in most college libraries where engineering is taught, in case anyone needs that kind of data.

Ed Huntress

I think I'll object to part of that. Aluminium and Titanium are elements. (period) Now as to steel and whitemetal I would go along with. ...lew...

If you were getting it from a technical source that supplied manufacturers with engineering specs for materials, you'd get the same thing as C90500. The Brits call it "G1," which is the same 88-10-0-2 alloy as C90500. The designations vary around the world, but most are indexed to the International Copper Association standard, which is actually US-based, and which, in this case, is what they call C90500.

If you were getting it from someone who supplies hobbyists, it should be some tin-bronze within a reasonable range of C90500.

You could email the ICA in the UK and just ask:

International Copper Association Ltd.

5 Grovelands Business Centre, Boundary Way Hemel Hemstead, Herts United Kingdom HP2 7TE Phone: +44 1442 275 705 Fax: +44 1442 275 716 (email is web-based; click on this link): Angela Vessey, Director

Ed Huntress

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Just make sure that you get the *right* ICA in the UK. I happen to be a member of the "International Concertina Association" which (of course) goes by the same acronym, and which could probably tell you

*nothing* of use about gunmetal. (Though there is another copper-based alloy which might be of interest to them (and to me), called "Reed brass" or sometimes "Reed bronze". Older concertina reeds were made using this, and I think that modern harmonicas also use something very similar.

Enjoy, DoN.

And the Irish version will give you the Irish Countrywomen's Association -

They probably know even less about gunmetal than the Concertina people :-)

Ivor.

This reference suggests that Brittish G1 is not the same as C90500.

manufacturers

Now, there's a real potential danger.

I can't help you there. It could be almost anything, as many brass and bronze alloys have the necessary spring characteristics, and there are dozens of standard alloys.

Low-brass and C43500 are commonly used in the manufacture of musical instruments. But brightness or corrosion resistance may be a more important issue for reeds, I don't know. If so, it could be something like Lusterloy.

Ed Huntress

I'm not following you. I read the reference you're pointing to, and it says they're exactly the same thing.

What am I missing?

Ed Huntress

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I wasn't really asking you for the proper alloy. consider that it was first used back in 1829 (when Sir Charles Wheatstone got his patent on the instrument -- including a mouth-blown one called the "Symphonium". That one, I believe, had gold plating on the reeds for corrosion control. The regular concertinas did not really have such problems, as I have seen instruments from at least 1850 which had no corrosion problems.

If it weren't for the hazards, I would consider BeCu to be a good choice. But most people who tune concertinas will be doing so by filing the reeds, and often testing the reed with an inhale through it. Really bad news with BeCu.

Phosphor bronze might work well -- I want to investigate that someday.

Thanks, DoN.

Both of those are very strong and make good springs. If you file it though, using the Be stuff, as you suggest, would be like sucking on a radium watch.

Ed Huntress