Sanforization is the denim-finishing process patented in 1930 to make cotton garments resistant to shrinkage.
The process was developed by Sanford Lockwood Cluett, an American inventor associated with the Cluett, Peabody & Company shirt business. It mechanically compresses and stabilizes woven cotton fabric before the garment reaches the customer.
Before sanforization became widespread, cotton clothing could shrink noticeably during washing. This was especially inconvenient for jeans, which were often bought before washing and expected to retain a predictable fit. Sanforized denim made sizing more reliable for mass-produced clothing.
Sanforization does not mean that denim can never shrink. Washing conditions, heat, and the fabric’s construction still matter. It is also different from stonewashing, which changes a garment’s appearance, and mercerization, a treatment mainly associated with improving cotton’s luster and strength.