Plating
1) silver plating - adding a coat of silver plate is partly for appearance and partly for the belief that it is more benign to skin than brass. It can be a fairly simple process.

2) imperfections- Imperfections can be buffed out of well used brass. I suspect that it adds no more variation than the maker's variations (as it seems well known that there is a significant variation from - for example - mouthpiece to mouthpiece.

3) functional plating - when valves become so worn that they detract from the performance of the instrument, then it is time to a) build them up in copper to the correct tolerances and then b) to plate them with the wear resistant nickel or chrome surface.

Oct 18th, 2005
Do any of you guys do your own plating? I've thought about it and tried it a few times just to see what's involved.

It's the fumes that put me off. You must have good ventilation and a place to work.
It's valve plating that interests me as much as anything. One of these years I've got to learn more about working on valves- building up walls and cylinders.

The main stumbling block to working on valves is the lack of a CNC. They're darned expensive.
During the short time I played around with plating, I learned how to dip and plate to create pretty effects on bells. The thing I did not learn is to control the color boundaries to make sharp lines between colors. But it's not rocket science. I did a few bells in copper/nickel, then nickel, then nickel/bronze, then nickel again so that the bell from the bell bow was light copper, then nickel, then light bronze, then nickel again. Looked right purty, like a metal lollipop.

Reply #1 - Nov 19th, 2005,

I have several mouthpieces that should be replaced. They look like heck and the rims are now bare brass, or almost. I am susceptible to brass contact allergy on my lips and need to find a way to replate these old pieces or, find a silver platter who is willing to plate these for a price less than double the cost of a new Bach or Benge m/p.

Reply #5 - Aug 25th, 2018, at 5:12pm
A standard engine lathe for piston lapping is handy, but there are work arounds for even that. But spinning valves when lapping can be problematic. Slight imperfections in the roundness of the casing can cause a poor fit when the actual action of the piston is not in spinning. The alternative is to lap in the piston by having it travel in the same path it is going to use when played.

Although not visible to the human eye, spinning causes microgrooves perpendicular to the stroke direction.

Typically, lapping compound grit 900 is used for the main work, and 1200 for the finish.

Rebuilding pistons involves steps prior to lapping. They must first be resized by electroplating copper onto the piston. They were honed between copper plating until they were perfectly straight and round with no dents or pitting. Copper plate on a valve can easily be measured with a micrometer, while sliver plating cannot. Plating thickness is a function of time and electrical current. Copper is a much better conductor of electricity due to its valence structure...i.e., the number of electrons zooming around its nucleus and the number of electron shells. After the final copper and honing, all were plated once with nickel which was .004’-.0065'' thick. Then they are ready to be honed into the casing.

Dan Oberloh shows his technique:
http://www.oberloh.com/gallery/tubavalvereferbish.htm