Why fabric shrinks?
Woven and knitted goods are 3-dimensional arrangement of crimped yarns. Fabric forming processes take straight lengths of yarns and force them into 2-dimensional crimped lengths. The degree of crimp is a function of the yarn size and fabric construction. This stable arrangement is the point where the relaxed fabric no longer shrinks in width and length, is also related to yarn sizes and fabric construction. It wet process they go on different stretching process which needs to be relaxed after the process. So the fabric shrinks. Excessive shrinkage is undesirable for fabrics to be made into garments. Here, the residual shrinkage should be less than 2% otherwise the garment will not fit after it is laundered.
See attachment figure for better understanding-
