How does sandpaper hold abrasive grains on a flexible backing?

Sandpaper, also known as coated abrasive, consists of abrasive particles secured to a flexible backing—such as paper or cloth—using an adhesive bond.12

The manufacturing process involves several key steps:

• Initial Coating: A layer of adhesive is applied to the backing material. Abrasive grains are then added, either by gravity or through an electrostatic process that orients sharp edges outward and controls grain spacing.1
• Drying and Sizing: The material is partially dried before undergoing a sizing operation, where a second layer of adhesive is applied to reinforce the bond.1
• Final Curing: The product is dried thoroughly and wound into rolls.1

The adhesives used vary based on the intended application. Water-soluble adhesives are common for dry or household sanding, while resin-based bonds are preferred for severe operations, as the heat generated during grinding can actually increase their holding strength. The overall effectiveness of the sandpaper is determined by the type of abrasive, grit size, grain density, adhesive strength, and the flexibility of the backing.12