Sandpaper from Sand, Hide Glue and Paper

A coated abrasive is grit glued to a backing. The first recorded one, in 13th-century China, bonded crushed shells, seeds and sand to parchment with natural gum. Here clean quartz sand is crushed, sieved into grades and scattered on paper brushed with warm hide glue. Sieve mesh only roughly matches a shop grit number: real P grades are set by ISO 6344. Quartz grit on hide glue wears faster than garnet or aluminium oxide paper, and water softens the glue, so use it dry.