Sanforization is a post weave process, patented by Sanford Lockwood Cluett in 1930. It is a method of shrinking and fixing the woven cloth in both length and width before it is made into garments and other items.

The fabric to be sanforized is moistened by water and/or steam, this lubricates the fibres and reduces the inherent friction within the fabric. Once moist, the fabric enters the sanforization process proper. Here, an endless rubber belt is squeezed between a pressure roll and a rubber belt cylinder, it is here that the stretching of the elastic belt surface occurs. The more the rubber belt is squeezed, the more the surface is stretched. This point of squeezing is known as the pressure zone, or the nip point. The fabric is fed into the pressure zone and upon leaving it, the rubber belt recovers itself and the surface returns to its pre-squeezed (stretched) size carrying the fabric with it. The effect of this action is a shortening of the warp yarns, which packs the filling yarns (weft), closer together: at this moment, shrinkage occurs.

After compaction, the fabric enters a dryer where the fibres are locked in their shrunken state as the moisture is removed from the fabric.

Jeans made from sanforized denim will not shrink unless harshly treated (for example being washed very hot or tumble dried at high heat).