Controlled Compressive Shrinkage (Sanforizing)
The internationally well-known and most important shrinking process today dates back more than 70 years. Though the correct expression for this process is Controlled Compressive Shrinkage, the average person knows it as SANFORIZED. The process is a purely mechanical treatment without any addition of chemicals.
The word SANFORIZED is derived from the first name of the inventor of the compressive shrinkage process, Mr. Sanford L. Cluett.
The Sanforized Company, a division of Cluett Peabody & Co., Inc., New York, USA, is sole owner of the registered trademarks Sanforized, Sanfor and Sanforizado.
The Sanforized label means dimensional stability for garments made up of Sanforized labeled fabrics.
The purpose of the process is to shrink fabrics in such a way that textiles made up of these fabrics do not shrink during washing.
The amount of potential wash shrinkage must be determined prior to shrinking. A full width sample is wash-tested according to the test method. After the lengthwise and widthwise shrinkage has been determined, the compressive shrinkage machine can be adjusted accordingly.
The process can be described by the following schematic:
Fabric (F) passes through the skyer (S) or other moistening device and is moistened by water and/or steam. This will lubricate the fibers and promote shrinkability within the fabric. Normally, a fabric must be moistened in such a way that every single thread achieves a moisture content of approximately 15%. This allows compression of the fabric with very little resistance.
When the fabric passes through the clip expander (C), we obtain the required width. The clip expander also transports the fabric to the most important part of the machine: the rubber belt unit (indicated by arrows in above figure). In the close-up of fig. 1, we see the endless rubber belt (R). By squeezing rubber belt (R) between pressure roll (P) and rubber belt cylinder (RB), we obtain an elastical stretching of the rubber belt surface. The more we squeeze the rubber belt, the more the surface is stretched. This point of squeezing is known as the pressure zone, or the nip point.
Fabric (F) is now fed into the pressure zone. When leaving the pressure zone, the rubber belt recovers itself and the surface returns to its original length carrying the fabric with it. The effect of this action is a shorting of the warp yarn which packs the filling yarns closer together. At this actual moment, shrinkage occurs.
After compaction within the rubber belt unit, the fabric enters the dryer (D). Here the fibers are locked in their shrunken state by removing the moisture from the fabric.
After the compressive shrinkage process is completed, another sample of the fabric is taken. This sample is also wash-tested. The final result of this test must meet the Sanforized Standard, in length and width before it may carry the Sanforized label.
All Sanforized Licensees are contractually obligated to follow the required test method and meet the standards set forth by The Sanforized Company
Ref: Courtesy: rauf.com