Sandpaper is used to remove materials, such as dirt, paint, etc from the surface of metals or ceramics.  Sandpapers consist of sheets of paper, one side of which is coated with an adhesive.  The paper can be held and rubbed against the surface, which is to be cleaned. 

Originally, Sand, glass or seashells were used as abrasives. Today, however, the abrasives used are aluminium oxide and silicon carbide. 

Sand papers are also known as emery papers.  The sandpapers are standardized according the size of particles they contain. The sand paper number specifies the finenes of the abrasive used.  A higher number indicates greater fineness. A number 6 will have coarser particle than a number 20 sand paper.

Backing refers to the paper or fabric to which the abrasive crystals are bonded.  The backing can be cloth, polyester, rayons. 

The abrasive is bound to the backing by means of a adhesive substance called the bonding.  The bonding should be strong enough to hold the abrasive while the rubbing action takes place. 

Clogging is the accumulation of dirt and removed material between the abrasive crystals.  This can affect the effectiveness of sandpaper action.  Wet Sandpapers can be used with a liquid, such as water to remove the clogged impurities.