Sanforizing
Also searched as: Sanforized, sanforisation, compressive shrinkage, compressive shrinking, preshrinking, pre-shrunk
A mechanical compressive-shrinkage finish, associated with the Sanforized trademark, that preshrinks woven cotton fabric lengthwise so the finished cloth shrinks little in later washing.
In detail
Weaving and wet processing stretch cotton fabric lengthwise, and washing lets the yarns relax, so untreated cloth shrinks. Sanforizing forces that shrinkage to happen in the mill. The fabric is dampened and heated, then carried on a thick, elastic rubber belt that is stretched as it wraps around a roller and then contracts; the fabric pressed against the belt surface is compacted lengthwise along with it. A heated drying cylinder then sets the compacted structure. The target is a low residual shrinkage specified by the trademark owner's standard.
The science and numbers
Residual shrinkage is measured by marking benchmarks on a specimen, laundering and drying it under a defined procedure, and calculating percent change in each direction. Compressive shrinkage machines control the fabric's moisture content and temperature so that yarns are plastic enough to crimp more tightly; the belt's thickness and tension determine how much compaction occurs. Operators set the compaction from a prior wash test of the fabric, aiming to remove the potential shrinkage without overshrinking, which would cause later growth. Related compaction methods apply similar principles to knitted fabrics.
A practical example
Two lots of the same denim are sewn into jeans, one sanforized and one left unsanforized, as some raw denim is. After a hot wash, the unsanforized pair shortens noticeably in the leg while the sanforized pair stays close to its labeled length. A student can measure marked squares before and after washing to calculate percent shrinkage in each direction.
What to distinguish
Sanforized is a trademark for a certified process result, not a generic synonym for any preshrinking. It mainly controls lengthwise relaxation shrinkage in woven fabrics; it does not prevent shrinkage from felting, heat damage or poor garment construction. Unsanforized fabric is not defective; some buyers choose it deliberately so the garment shapes itself to the wearer through washing.
Origins and history
The process was developed in the United States by Sanford L. Cluett of the shirt and collar maker Cluett, Peabody and Company, and the trademark Sanforized was coined from his first name. Mills were licensed to use the mark when their cloth met the owner's residual shrinkage standard, and the label became a familiar promise on cotton work and casual clothing in the mid-twentieth century. Denim sold as unsanforized is defined by skipping the step.
Related terms
Sources & further reading
Technical references reviewed 2026-09-22. Examples are illustrative. Industry organizations and manufacturers describe their own fields; their references are not independent product endorsements. Figures are approximate and depend on the stated test conditions.