Posted by Joe -an aside- S. on July 28, 2001 at 19:38:41:
In Reply to: Re: Play-testing at Shows & Conferences posted by Charles Page on July 27, 2001 at 18:01:22:
The first year with new pistons (trumpet, baritone, tuba) can be annoying as the casing surfaces are turning from "untarnished" yellow brass to brass oxide (the "break-in" period).
As the casings turn from yellow to brown, the oxidation needs to be scuffed smooth (as oxidation naturally forms "rough") by the daily heavily-oiled pistons. If some of the oxidation from the casings electro-plates itself on to the pistons, those greenish-brown deposits on your pistons are possibly the main culprit. They can be removed by a mild abrasive or by a mild acid. Again, once the casings finish turning brown and get scuffed smooth, you will probably have fewer and fewer problems with sticking pistons. Valve oil dumped down the mouthpipe (starting on day #1) also helps prevent lime from coating the mouthpipe interior.
Good luck.