Shrinkage of Fabrics… Why Fabrics Shrink?

Woven and knitted goods are 3-dimensional arrays 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. When fabric is completely relaxed, the crossing yarns will move around in relation to each other until a stable configuration is reached.
This stable arrangement, the point where the relaxed fabric no longer shrinks in width and length, is also related to yarn sizes and fabric construction. When stretching tensions are applied to the fabric, the crimped amplitude decreases and the fabric grows in the direction of the stress. Later when the tensions are relieved and the fabric allowed relaxing, the crimp amplitude returns to its stable configuration and the fabric shrinks. Many fabrics are stretched during wet processing as they are pulled from one operation to another. This is the major cause of fabric shrinkage.

Factors on which Fabric Shrinkage Depends

The shrinkage amount of fabric is dependent on:

1. The nature of fibers
2. The character of threads
3. The way of interlacing of threads in the fabric
4. Crimp in yarn
5. Cycle of washing or Number of washing

Shrinkage Standards for a Fabric

• Woven fabrics shall not either shrink or gain in excess of 1% in either the warp-wise or the weft-wise direction when subjected to the washing.
• Knit fabrics shall not either shrink or gain in excess of 5% in either the longitudinal or the cross direction when subjected to the washing.