I think I may have detailed this elsewhere, but I just had to do it again on a Union chest and took some pictures. The Union backers are a little thicker and larger in diameter than the Gerstner's, so they hang over the edges of my fixture. I affix them each with an Allen screw and them spin them on high speed against a microfiber cloth with Simichrome polish on it.

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I chuck the knobs straight into the drill and polish them likewise.

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More detail here: https://gerstnertoolchest.shutterfly.com/union/2440