Fabric Shrinkage and Procedure of Shrinkage Test

The term ‘shrinkage’ can simply be defined as a change in the dimensions of a fabric or garment. This dimensional change may be in a positive (growth or elongation) or negative (shrinkage) direction for fabric length, width and thickness. Although the thickness of a fabric also changes with processing and use, it is not usually considered problematic. For a cotton fabric, shrinkage relates to the loss of the length and/or width dimensions. In garment form, the shrinkage characteristics relate not only to a change in fabric dimensions, but they also can relate to other parameters, such as seam puckering, torquing and overall garment fit.Get more news about fabric relaxing or shrinking machine,you can vist our website!

Shrinkage is the process in which a fabric becomes smaller than its original size, usually through the process of laundry. Cotton fabric suffers from two main disadvantages of shrinking and creasing during subsequent washing. However, there are fabrics which are more naturally resistant to shrinking. Synthetic fibers such as polyester or nylon are typically less prone to shrinking than others, although they are not 100% shrink-proof.
Any fabric shrinks in different states, from loom state onwards to the stage till it is finished. It can be recalled that width of warp on beam (weavers beam) is different from width in reed, width of fabric on front rest differs from width in reed, width on cloth roller differs from relaxed width and finished width is smaller than grey width. Answer for all these changes is ‘shrinkage’, of cloth width wise and length wise. In some cases fabric shrinkage is high and noticeable, e.g. 10s warp sized with 10%, 34s or 40s reed, 8 or 10 pick wheel using 2s roving as weft to produce ‘chaddars’ or thick bed sheets. When grey fabric subjected to preparatory process like desizing, scouring, bleaching or mercerizing, fabric undergo shrinkage. Thus, if a cloth is finished, we need to calculate from reverse side to arrive at width of warp on beam.

After cotton fabric is constructed on a knitting machine or weaving loom, it has inherent characteristics based solely on the yarn construction variables used. These characteristics or conditions are referred to as the greige delivered state and can be tested for various specifications, including shrinkage. The type of shrinkage measured at this point is defined as construction shrinkage, which is the amount of dimensional change in a fabric based solely on the construction variables used to create the fabric. Construction shrinkage is measured after fabrication but before subsequent processes.

These steps create processing shrinkage, which can be defined as the dimensional change that a process adds to or removes from the construction shrinkage of a fabric and thereby changes the residual shrinkage accordingly. The length and width dimensions are both affected, and the fabrics may either be stretched or consolidated. Most often, the length is stretched and the width is reduced during wet processing. Some of this shrinkage is composed of elastic shrinkage and can be easily recovered; however, some of the changes in dimensions may not be recovered because the elastic limits of the fabric as constructed have been exceeded.

Elastic shrinkage:
Elastic shrinkage is defined as a change in the dimensions of a fabric as a result of the fabric’s ability to freely relax from the tensions experienced during construction and other processing.

4. Drying shrinkage:
Drying shrinkage is defined as a dimensional change in a fabric when the ‘deswelling’ of fiber, yarn and construction occurs in the drying step. The structure shrinks upon itself as a result of the physics of drying. Continuous processes during dyeing and preparation for drying usually stretch the length and pull down or reduce the width, sometimes beyond their elastic limits, thereby changing the relaxed dimensions.