Posted by Mr.Know-It-All on June 27, 2003 at 19:44:07:
In Reply to: Re: Re: Re: Weight difference/plating posted by Joe Baker on June 27, 2003 at 12:29:02:
In responce to a few of the posts,This is what I know about plating horns,
Plugs are not used. The line inside the tuba or Euphonium's bell throat is where the electrolytic solution reaches before the air trapped inside stops its advance. Plugging the horn up would trap air inside and allow it to bob in the tank causing all sorts of problems. Plating between the casings, slides and bows is not a real issue because the cathode (part being plated) is gently swayed back and forth by mechanical means in the (silver cyanide) solution. This circulates the silver depleted liquid away from the part being plated and replaces it with fresh silver to be plated on the surface. The solution inside the instrument is depleted and becomes stagnant, void of silver. The current flows over the surface of the cathode as it is the path of least resistance, this is because prior to silver plating the part is ''copper struck'' to insure even current flow over the complete surface. The voltage is set at the proper rate, 1-5V is typical depending on the size of the part being plated and the size of the plating bath. Low voltage also helpes the tight areas get sufficient plating. The amperage is kept to a minimum to avoid burning the finish.
I am having a hard time accepting 12 oz. of silver on a tuba, that is a lot of metal, relatively speeking and having been a plater in a former life, to move that much material in the time given, there would have be a great deal of action taking place in the plating bath to be sure. When I did plating and the plating math of any part was figured, the part was treated like a big box not a bunch of little boxes. I am sure this was not the case when doing structural plating like hard chrome or electroless-nickel (which I never did as that was a department I had no desire to work in) but decorative plating was not treated as rocket science. My guess is that the amount of silver(heavy plate) on a full size tuba was 4-6oz. tops but thats just a guess.
Mofwiw
Daniel " wish I was as smart as Rick Denney " Oberloh
Oberloh Woodwind and Brass Works
Saving the world, one horn at a time...
www.oberloh.com