What is shrink and how cotton shrink

Shrink

 Shrinkage is the contraction in the dimension of fabric due to usage.

Cotton fabric suffers from 2 main disadvantages of creasing and shrinking during subsequent washing. Creasing is overcome by the Resin finishing whereas the shrinking is prevented by a special finishing known as Sanforising and the machine used for that purpose is known as Zero - Zero Pre Shrinking machine

 How cotton shrink

Cotton has the property of swelling in water and this effects Shrinking Also the  mechanical stress, strain and tension, during spinning and weaving etc, when released causes the fabric to shrink

The cotton fabric, when put in water, swelling takes place and rearrangement of internal forces takes place. The fibres will become free from tension and it comes to the original tensionless state.

                                              

 These are the reasons for shrinkage.

 case of a fabric, the warp yarns are under much strain due to interlacement than the weft yarns. Hence, when a fabric is allowed to shrink, the warp yarn shrinkage will be more than weft yarn. To overcome this, the fabric is extended in widthwise to some extent in the stenter machine during the finishing process. Then it is subjected to the preshrink process.

    

Mechanism

The mechanism or principle adopted to produce shrinkage is "To place the fabric on the extended surface of a rubber blanket represented by the concave surface When the tension is released on the blanket, it shrinks, The fabric which is in close contact with the rubber blanket at the concave surface has no way other than shrinking along with the blanket." This principle is used to produce pre shrinking finish with the help of a sanforising or Zero-Zero machine