abrasive grains stuck to a backing of some sort. Sandpaper is the most common example, and has been in use since its invention in China in the 13th century in the form of crushed shells and sand ...
The Family Handyman on MSN29 天
Sandpaper Grit Chart
Variations include: Abrasive material used; Type of backing; Format (sheet, belt or disk) for specific sanding machines. Grit ...