Luthiery Laboratories

A subject so simple you hardly even consider it, yet really very mysterious. Just what is the roughness of sandpaper, and the relation to the number on the package?

Here's a plot of some numbers I found online: sandpaper "grit" versus actual micron size. Interesting to see what size scratches you are taking out ( or putting in. ) The curve starts at 320, which is the coarsest grit that might be considered part of the finishing process. For final finishing like orange-peel removal, I start with 1500 and work up from there, I find that even 1000 leaves scratches that are difficult to remove.

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