Shrinkage is a natural behavior of garments. Actually, the fibres get relaxed when we immerse them in water for washing at home. Fabric passes thru lots of stress and tensions during the fibre to yarn and then yarn to garments. Water acts as a relaxing agent and reduces the tensions and garment tries to achieve a stable shape, in the process it may de-shape(spirality/skewing) or shrink( minus shrinkages or extend).
The natural fibres are hygroscopic in nature, and they absorb more water henceforth they shrink more than synthetic fibres/ fabrics (because synthetic fibres are more crystalline in nature and hydrophobic). Synthetic fibres are thermoplastic in nature, they can help in controlling shrinkages by heat setting the fabrics.
Although the blend of 60% cotton and 40% polyester should be more dimensional stable than 100% cotton. it also depends on a few other factors like
- Loosely weaved or knitted structure can shrink more irrespective of the blend.
- Machines gauge— needle per inch decides the tightness factor. Wrong gauge selection may cause shrinkages.
- If the fabric is not pre-heat set garments may shrink.
- Appropriate selection of yarn count, thread count, stitch length, preheat set fabrics, proper post-wet process-finishing processes. pre-shrunk garments will shrink less.