The higher the number, the finer the grit. Coarse grits progress from 24 to 30 to 36, while fine ones rise from 600 to 800 to 1,000 and beyond. Because coarse and fine sandpaper grits are used ...

Then, it’s off to sanding with 200 and 600 grit wet sandpaper. Slowly, the soldermask is removed and the top copper layer appears. After that, it’s just a matter of sanding and scanning ...