Non-aqueous Solvent Medium (NASM) Dyeing for Textiles

In the traditional aqueous dyeing process, large amounts of water are consumed and the wastewater has to be discharged to the environment. Due to increasing environmental awareness, water-less dyeing technologies have received considerable attention in the textile industry. One such technology is Non-Aqueous Solvent Medium (NASM) dyeing.

Supercritical carbon dioxide (Sc-CO2) is a NASM candidate suitable for textile dyeing. Sc-CO2 is CO2 in a state above its critical temperature and pressure. A number of dyestuffs used in industry are soluble in Sc-CO2, making it suitable for textile dyeing.

HKRITA has developed a Sc-CO2 dyeing system that is capable of dyeing synthetic, natural and blended materials.


The project has developed a pre-industrial scale system with two dyeing vessels with each 200L. This one-system-for-all design is able to carry out dyeing processes on yarn, fabric or whole garments. Its dyeing capacity is up to 20 kg of yarn cones within four hours.  Also, about 5 kg of garments can be dyed, depending on their sizes and shapes.

Industry benefit

The time required for NASM dyeing ranges from 60 to 240 minutes compared to 180 to 240 minutes required for water dyeing..

Up to 90% of the NASM used in the dyeing process can be reused. Since it is a waterless process, waste water treatment facilities are not required and the overall operating cost could be reduced by 5% or possibly more.

Technological breakthrough

This one-system-for-all design which is able to carry out dyeing processes on yarn, fabric or whole garments is the first of its kind in the industry.

Licensing Details

For more details, please contact us. (Email:; Tel: (852) 2627 0180)


Award Name
Bronze Medal in the 47th International Exhibition of Inventions of Geneva (2019)
Related ITF project
Research Start Date 2016-04-29
IP Number
19 162 459.2