Shrinkage is the process in which a dimensions of fabric reduces and fabric becomes smaller than its original size (either widthwise, lengthwise or both), usually through the process of laundry/washing. Cotton fabric suffers from two main disadvantages of shrinking and creasing during subsequent washing. If shrinkage is higher in the fabric, it has poor dimensional stability. Fabric with higher amount of shrinkage is having negative impact on correct fitting of garment. Which is why it is very useful to have an idea of how fabric shrinks as well as types of shrinkage in fabric. Types of shrinkage in fabric are discussed in following points.
1. Relaxation
When yarns are woven into a fabric, they are subjected to considerable tensions, particularly in the warp direction, although the filling (weft) yarns are also stretched. In the subsequent tentering and calendaring operations, this "stretch" may be further increased and temporarily "set" in the fabric. The fabric is then in a state of dimensional instability, and when it is wetted thoroughly, it tends to recover dimensional stability, which results in a contraction of yarns, giving rise to what is termed "relaxation shrinkage." The contraction in the filling direction is normally considerably less than in the warp direction, although in some fabrics it can be high enough to cause complaint unless steps are taken to counteract it.
2. Swelling
Shrinkage that results from the swelling and de-swelling of fibers because of the absorption and desorption of water is called swelling shrinkage. In a loosely woven fabric, the effect of this swelling of the yarns is greater than in a tightly woven fabric, since there is greater freedom of movement.
3. Felting
Shrinkage that results primarily from the frictional properties of the component fibers which cause them to migrate within the fabric/yarn structure is called felting shrinkage. This is normally considered to be significant only for fibers having scales on their surface, such as wool.
4. Contraction
This is the decrease in length that takes place in synthetic yarns/fabrics when they are exposed to temperatures higher than 210C. The tendency of synthetic fabrics toward contraction shrinkage can almost be eliminated by heat-setting the yarns. Synthetic yarns that are not heat-set before or after they are converted into a fabric will shrink due to steaming and/or pressing during apparel manufacturing.
Shrinkage of a garment can occur when it goes through one or more of the following processes Laundering, mostly relaxation and swelling shrinkage (felting shrinkage in the case of wool fibers). Dry-cleaning, mostly relaxation and swelling shrinkage (felting shrinkage in the case of wool fibers). Steaming, contraction shrinkage in the case of synthetic fabrics. Pressing, contraction shrinkage in the case of synthetic fabrics
