Importance of heat setting

Heat set procedure of polyester fabric:

The process of heat setting is used to stabilize yarn twist, removing residual shrinkage, increase wrinkle resistance and obtain durable pleat. Polyester may shrink 7% at boil and even more at higher temperature.

The importance of heat setting:

1.     To modify crystalline structure.

2.     To improve dimensional stability.

3.     To resist
wet creasing during washing. 

4.     To increase safe ironing temperature.

5.     To avoid shade variation.

6.     Affect water inhibition.

 

The disadvantages of heat setting:

Heat setting can be done before or after dyeing. If the fabric is set heat before dyeing , the absorbency of fabric goes down and if it is done before scouring and bleaching then the dirt dust may permanently deposit on the fabric. If heat setting is down after dyeing then some dye may sublime at high temperature and thus cause shade variation. The time of heat setting depends on the fabric state i.g. grey, scoured, bleached etc. It also depends on count of yarn on fabric. For heat setting hot air, hot roller or radiant machine can be used.