> Hi Kit, > > In the US at least, almost, if not all, mouthpieces are made of C360 > free-cutting brass rod. It has 2.5-3.7% lead content. I've never seen or > heard of any situation where that caused a problem
I guess part of the problem with lead is that it is harmful at very low levels. It can cause subtle but measurable behavior changes and reductions in IQ long before it causes any of the classical symptoms of lead poisoning. The fact that individual people don't notice problems and then attribute them to their mouthpieces doesn't mean that they're innocuous. Apparently in leaded brass, the lead is not held in the copper/zinc matrix but more as a sort of emulsion of 1-3 micrometer globules and 10 micrometer spicules of pure lead spread throughout the brass. I did some back-of-the-envelope calculations and came out with a figure that there was about 0.5mg of pure lead on the surface of my mouthpiece rims, just waiting to be leached off. As the mouthpiece wears down, yet more will be exposed - I have no idea how fast a mouthpiece wears down. Compared to the amount I was probably exposed to as a kid, this is nothing. Although I don't take my guesstimate too seriously, given that the Californian maximum acceptable allowance is 0.5 micrograms per day per product, it actually does seem a quantity worth avoiding. > but I don't believe > in tempting fate so all our mouthpieces are plated. We usually use gold > for the rim and silver on the cup but all silver is also good. We can > also make delrin rims to further reduce potential lead exposure. > > Of the alloys you mention, CZ121 is the most nearly equivalent to C360. > It has 58% brass and 3% lead and it's machinability index is 90 > (C360=100). The other alloys you mention contain about 1.2% lead and > have a machinability rating of 30. Non-starters, I think. I had a 4mm cz108 half-hard plate delivered through the post today, cut a hexagon out of it and machined it down to a circular disk on the lathe. I used the same tool I normally use for steel and it cut fine. I actually found it an easier process than cutting disks out of brass rod using a parting tool, which is how I've heard of rims being made before. This is not a disagreement by the way - I'm basically just making large brass washers, which is a very different enterprise from making whole mouthpieces on the lathe. > The common alloy for sheet metal here in the US is C260 cartridge brass. > While it's lead-free, the rim on most sheet metal mouthpieces is a > turned piece that is soldered on. More lead! Not any more! I've been using a 95% tin, 5% silver solder. Interestingly, my antique natural horn mouthpiece actually didn't use solder at all and when its previous owner dropped it the rim fell off. A few of my theories are that: 1) They knew about the dangers of lead solder and wanted to avoid it 2) Even in the 1700s - 1800s, you could go to a mouthpiece shop and buy your cup and rim separately then have them pressed together 3) The solder is slightly unsightly as it's a different colour from the brass 4) The solder will probably wear at a different rate from the brass, and will either leave a ridge, or more likely a depression, on the surface of the rim If anybody actually knows the answer - or how common it was for rims to be soldered in the 18th-19th centuries - I'd be interested to hear. I'm planning to go and see some in museums, but it isn't always apparent how they've been constructed. > In any case, it's no > problem to plate a sheet metal mouthpiece. Alloys other than the most > common ones can be expensive and hard to get (think 5000lb minimum > order) and I don't see any advantage. Everybody uses C360 because it has > proven to be the best alloy to work with. I agree with you about plating mouthpieces. Even though I can now use 'lead free' brass I think I will be on the safe side and get them plated. Either that or I'll look into Sterling silver. > Good luck with your mouthpiece project. Thank you - it's been a lot of fun. I already have a few mouthpieces that have turned out quite nicely. I'll post some pictures of the whole process when I've had a bit more practice. Kit > > Bob Osmun > www.osmun.com > > PS-Mr. Austin's opinion notwithstanding, I doubt if any of us is too > keen to have "a big spinning ribbon of razor wire" coming off our lathe! > > > Kit Wolf wrote: >> I've recently been dabbling in making mouthpieces for natural horns, and >> I >> noticed that the only grades of brass that seem readily available for >> turning (e.g. CZ121, CZ114 / CW614 and CW721) both contain lead. CZ121 >> contains about 4%; CZ114 contains about 1%. >> >> Although this isn't a great problem for me - I can use sheet metal - >> does >> anybody know what metals/alloys are generally used to make mouthpieces, >> and whether or not it's worth worrying about leaded brass from a safety >> perspective? I have several old mouthpieces where the plating is wearing >> thin, or that were simply left unplated from the outset. >> >> Kit >> >> >> _______________________________________________ >> post: horn@music.memphis.edu >> unsubscribe or set options at >> http://music2.memphis.edu/mailman/options/horn/rosmun%40osmun.com >> >> >> > -- Sometimes my Email program gives the wrong return address. If you have any trouble replying to me, use 'c.j.l.w...@newcastle.ac.uk' and not 'n802...' Sorry for any confusion _______________________________________________ post: horn@music.memphis.edu unsubscribe or set options at http://music2.memphis.edu/mailman/options/horn/archive%40jab.org
