Posted by John Swensen on January 20, 2000 at 16:22:30:
Scenario: after polishing, thoroughly cleaning, and lubricating a first valve slide, it moves smoothly and quickly, with no roughness or grating. A few days or weeks later, the slide gets scratchy, and careful wiping and relubrication does not help. Closer examination shows one or more discolored, irregularly-shaped spots that can be felt with a fingernail. Lightly repolishing the slide (a few seconds with Brasso, Simichrome, or a similar product on a rag) makes everything smooth again for another few days or weeks, but the spots seems to return in the same place. The spots appear to grow from discoloration only, to raised areas over time, as observed when removing the slides to drain water. 40-power magnification of these spots shows a brass coloration of the spot, relative to the white-colored nickel silver slide.
This seems to happen both to nickel silver slides in nickel silver slide tubes, and brass slides in brass slide tubes (different horns). I have noticed this while using Phil Wood bicycle grease, anhydrous lanolin, and Hetman synthetic slide oil, although I have not tried to determine any correlation between lubricant and the rate of reappearance. I always brush my teeth and rinse before playing, by the way, and my horns and mouthpieces are kept very clean.
Have others noticed these "scratchies" appearing on their slides? Does any one know what is causing them, and if anything can be done to delay their reappearance?