Sanforization is a process of treatment used for cotton fabrics mainly and most textiles made from natural or chemical fibres, invented by Sanford Lockwood Cluett (1874-1968) in 1933. It is a method of stretching, shrinking and fixing the woven cloth in both length and width, before cutting and producing to reduce the shrinkage which would otherwise occur after washing.

The cloth is continually fed into the sanforizing machine and therein moistened with either water or steam. A rotating cylinder presses a rubber band against another heated rotating cylinder, thereby the rubber band briefly gets compressed and afterwards shrinks to its final size. The cloth to be treated is transported between rubber band and heated cylinder and is forced to follow this brief expansion and recontraction and thus gets shrunk.

The bigger the pressure applied to the rubber band the bigger the shrinking afterwards.

The aim of the process is a cloth which does not shrink during clothes production by cutting, sewing or by wearing and washing the finished clothes.

For technical application cloth may be specified to have a shrink-proof value of under 1%.