A sanding disc is essentially a flat, circular piece of sandpaper. One side of the disc is coated in an abrasive coating, typically aluminium oxide and silicon carbide.
The holes in a sanding disc and sanding pad are there so that dust can be extracted by the in-built extraction system.
Hook and loop (Velcro)
Hook and loop (Velcro) backed sanding discs employ a system familiar to many of us.
The hooks line the random-orbit sander’s sanding pad and allow you to affix the looped sanding disc to it.
When the hooks and loops are pressed together, the hooks intertwine with the loops and snag, bonding the two surfaces together. Because they are flexible, the loops and hooks can simply be pulled apart when it’s time to change a disc.
Peel and stick
There are also sanding discs which use a “peel and stick” method.
These types of sanding disc have a self-adhesive back covered with a thin, removable outer paper. The outer-paper is peeled back to reveal the sticky side.
The self-adhesive side is then stuck directly to the sander’s pad. Make sure you check your user manual to see which type of sanding disc you need.