Posted by RU Sirius on March 25, 2001 at 22:54:08:
In Reply to: Re: Re: Deposits on valves and valve casings posted by Paul Roache on March 25, 2001 at 21:32:53:
Pitch is normally used in the bending of mouthpipes and other broad bends in the tubing. In the case of the crooks (and tuning slide bows) associated with the valve section area, the undersized tubes may be rough-bent enough to fit into a split block mold using pitch. Then they would be emptied and cleaned to allow for the passing of bore-sized balls which form the wall of the tube to the mold from the inside. This makes the bows and crooks very consistent in both internal and external dimension. Any residue left here would certainly be 'scraped' out by the passage of the balls.
Even if there were any residue in the mouthpipe or other odd bends not formed with a mold, I cannot imagine leaving any of it behind as proof of proper workmanship. Quite the opposite, indeed! Are we supposed to inspect the insides of the tubing for this proof of quality? And by what means?!! Imagine the smoky stench as the tubes are heated for soldering/assembly!!
A chem clean is probably a good idea for all of our instruments, regardless of age, but this sounds like back-pedaling doubletalk to these ears.