I just figured out the my beloved Spider trumpet stand has been wearing off the silver from inside my bell. A friend warned me of this and it seems to be so. On the top of each leg of the stand is a rubber insert that comes in contact with the bell. Rubber when in contact with silver plate turns it black, and the stain can't seem to be removed. I remember this happening with a rubber band used for holding in the third slide on a silver horn. I love using my Spider stand, but will have to figure out how to rectify this problem.