仕上げ
grit number
Japanese: 番手
A number indicating the grit size of a file. The higher the number, the finer the grit (#100 coarse → #1500 fine).
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The grit number is a number that indicates the coarseness of the particles in an abrasive material; the higher the number, the finer the particles (fine grit), and the lower the number, the coarser the particles (coarse grit). In the polishing process for glass fusing, you start with coarse grit (60–120) and gradually move up to finer grit (400–1000 or higher) in stages to ultimately achieve a smooth surface.
The selection of grit numbers for each step is determined by considering the depth of the scratches left by the previous step and the efficiency of the subsequent step. If you skip too many grit numbers and move on to the next step, it will take too long to remove the scratches from the previous step using a finer-grit wheel. The typical sequence is 60-grit → 120-grit → 220-grit → 400-grit → polishing compound.
This entry is written in Japanese by Rei Chikaoka and translated for readers outside Japan. If something reads oddly, the original is the source of truth.