Does a Brass Instrument Change Over Time?
First, let me say that I believe the answer is "Yes." But I'm starting this thread to share some posts from "The Mouthpiece" discussion forum.
http://www.themouthpiece.com/forum/t...ith-use.54829/
I found a few interesting stories, and a couple were from the automobile field (you know how I love to compare anything to cars). Here are the comments I found interesting:
Quote:
FROM MELLO:Instruments DO CHANGE ......from the moment they come proVery quickly frozen duction line At the risk of being accused of inaccuracies in describing particles - in non scientific terminology..for simplicity.
The following may be of interest. To make our instruments ....lets take a trombone as an example. .
The slidd es really bend round and tubes would normally split or collapse unless they are made into 'rods' by filling the tube before bending. Two common processes are traditionally hot lead . which when cooled , allow the tubes to be bent around shaped wooden blocks by special presses - by hand...then the tubes are heated again to allow the lead to be poured out , Modern methods which I have seen are MUCH quicker and simpler . imagine a large revolver ( gun )cylinder constantly slowly revolving. The straight tube lengths are inserted ( quasi bullets ) , as they rotate , one by one they are filled water , VERY quickly frozen solid, power bent to shape , Thawed & Mtd .... job done.
Bells on the other hand are sheets , cut to pattern , folded over , the two edges soldered , then by process of rubbing , hammering, rolling etc end up as a bell . ( the wide end being bent over itself with a bell wire inside > A crude description just to explain the brass is subjected to all manners of stress / heat and cold. This stretches , and compresses the 'molecular 'structure within the metal.
It is important to remember the metal is at its best when the 'molecules' have settled and returned ( as near as poss ) to their original state. This process is what we know as annealing . usually quickened by heating & cooling . All before we play it. Using enhanced methods is usually successful as far as the player is concerned , but the act of playing and the slight vibrations we make help it to finally 'blow in ' a term that used to be used. However the best and most natural method I believe is time ...simply time. Having said all that , you may realise that the shiny new instrument is still not always at its best. One other old practice was to ill a new instrument with milk , & leave it a few hrs before emptying . Then without washing it out , use it,,,,,the theory being that the residue levels what little rifling or unevenness of the metal inside would be smoothed out !. Food for thought .... & excuse the non technical terminology .. A little PS , Laquering & plating have an effect as do dents and bruising , but thats another story.
Quote:
FROM JACK E:You've reminded me, Mello, of what I read about the way Jaguars and I believe Mercedes used to treat the cast iron cylinder blocks of their car engines. After casting, they would dump them in a field, and leave them there for six months before machining them, and boring out the cylinders. What they found was that the castings changed in shape, as the internal crystal structure settled down, and the stresses caused by the rapid cooling of the cast iron sorted themselves out. Once thgat process was completed, they could be reasonably sure that when, for example, they bored out the cylinders, and the completed engine went into service, going through repeated cycles of heating up and cooling down, the cylinder bores would stay truly cylindrical, and their axes would all stay parallel to each other and square to the line of the crankshaft. If, in contrast, they machined the cylinder blocks as soon as they came out of the foundry, some of the blocks went slightly out of true in service - not enough to seize the engine, but enough to significantly reduce engine life.
In the case of air-cooled two stroke engines, it was well known by pro engine tuners and race mechanics that the running in process couldn't be done by just putting the engine on a test bed and running it continually for so many hours. It had to be done by repeated starting, warming it up, then running for a while before stopping it, letting it cool right down to ambient temperature, and then leaving it for a few hours. This temperature cycling had a dramatic effect of the extremely complex shape of the cylinder, with its ports running up through the cylinder walls, and allowed the structure to stabilise. If this repeated temperature cycling was not carried out, as soon as put it into racing conditions, the cylinder would change shape enough to seize the engine solid.
Mind, the crystal structure and crystal physics of objects made out of metal is an incredibly complex subject - that the London School of Science & Technology has a Professor of Crystal Physics says it all. This applies especially in the case of something with a shape as complex as a brass instrument, and is, as you point out, compounded by the myriad of processes which impose all sorts of strains on the finished structure. And think of the temperature changes the instrument suffers, when you take it out of your nice warm house into sub-zero air temperatures to play Christmas carols - and you blow air with a temperature close to 98 degrees F into the thin end of it, so that the temperature from the mouthpiece to the bell changes by about 100 degrees F!
Even though the brass used to make our instruments is a very malleable alloy of copper and zinc, I dread to think about the wracking strains imposed on them due to the hotter parts trying to expand more than the parts which are at far lower temperatures - especially on those outdoor Christmas gigs!