Sheet metal as used for our instruments does not age if properly kept. It can keep its qualities for hundreds of years even thousand years & more. We have such samples.
If the metal is not exposed too dry or too hot or too moist environment or too cold, nothing will happen. But old horns, found under the roof, well, those can have become very fragile. ################################################## Am 29.05.2011 um 19:35 schrieb Debbie Schmidt: > We have experts in this and I am not one. > > But I think there were 2 separate questions . > > The one about what happens when metal ages ... Walter Lawson was working on > my Geyer many moons ago and he told me that the metal became brittle with > age. Now the age of the Geyer he was working on was about 40 years or so. > > Debbie Schmidt Sent from my iPhone > > On May 29, 2011, at 1:30 PM, Steve Haflich <[email protected]> wrote: > >> _If_, as Jonathan correctly questions, the effect is real, then one one >> would need to investigate the relevant properties of the metals. I can >> think of three possible variables. >> >> (But first, remember that nickel silver is considered by metallurgists >> to be a particular _kind_ of brass. So if investigating metalurgic >> properties, general figures for "brass" won't be specific enough to >> help.) >> >> Water vapor condenses inside a brass instrument because the tube is >> cooler than the 35 degree C 95% humidity breath. The condensation of >> the water on the metal surface transfers heat to the metal, warming it. >> (This is called the "heat of condensation".) As the metal warms, less >> condensation occurs. When you stop playing, the metal cools again. The >> rapidly the metal warms during playing affects how long and how much >> condensation occurs. This is affected by both the specific heat of the >> alloy (probably not too different over the range of alloys used in >> brass) and the mass (i.e. thickness) of the metal, which can be very >> different between different instruments. >> >> My guess, if the effect is real, is that the thermal mass of the main >> tubing is somewhat different between the two instruments. >> >> There might also be affects from different surface conditions of the >> metal surface of the bore, for instance, difference in initial finish, >> corrosion, or coating of scum. Of course, temperature of the >> surrounding air, and whether the air is completely still or moving, will >> greatly affect the warming and cooling of the brass. >> _______________________________________________ >> post: [email protected] >> unsubscribe or set options at >> https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/jasoncat%40aol.com > _______________________________________________ > post: [email protected] > unsubscribe or set options at > https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/hpizka%40me.com _______________________________________________ post: [email protected] unsubscribe or set options at https://pegasus.memphis.edu/cgi-bin/mailman/options/horn/archive%40jab.org
