Relaxation Shrinkage Treatment for Knitwear

Knitted fabric requires relaxation to restore its expected properties and performance. This project developed a low pressure relaxation (LPR) process other than conventional washing and tumble drying cycle (WTD). The developed technology achieves water evaporation by lowering air pressure. Water expands in volume during evaporation. The force field created by the water vapour expansion of a garment could be effected at its fibres and yarns. Agitation of the garment will therefore take place.


The new relaxation process is suitable for open width knitted fabric. With appropriate mountings, knitted sweaters can be processed.

Industry benefit

The process is potentially beneficial to sweater production.  A WTD process usually comes before the final pressing in the sweater production line to correct dimensions and improve hand properties. Comparing to WTD, it is estimated that the new LPR process uses 19 times less electricity and 40 times less water as well as achieving 120 times faster on processing. Besides, the LPR offers a cleaner fabric appearance, higher pilling test grade and brighter colours especially for darker shades such as black and navy blue.

Technological breakthrough

The WTD process relaxes knitted fabric by mechanical agitation while the LPR one relaxes knitted fabric by micro-agitation originated from expansion of water during phase change. The latter can better preserve the fabric properties.

Licensing Details

A non-exclusive licence includes the right of making further R&D as well as sale of the system based on the filed patent.

The research deliverable is now open for licensing. For more details, please contact us. (Email:; Tel: (852) 2627 0180)

Related ITF project
Research Start Date 2015-03-25
Industry Partner
Loyal Asia (International) Co Ltd