“Red or Blue?” was the very important question that my husband, LR, so urgently needed to ask me at the outlet mall one weekend (We love to go to the outlet mall). LR was browsing through the items on sale at the Adidas outlet mall and found this sports t-shirt on sale. As usual, the choice of 2 colors has put him in a dilemma.

I took a look at the t-shirts and what caught my eye was not the color nor design, but the words printed at its back “DryDye”. What is DryDye technology? As far as we know, dyeing of textile produces tonnes of wastewater which requires energy intensive processes to treat and recycle. After dyeing, the textile need to be dried and that further requires more heat and energy. DryDye refers to the technology which uses almost zero amount of water to dye the T-shirt. How is this done?

The answer is in Carbon Dioxide. Often associated with bad press due the links of rising temperatures and atmospheric CO₂ levels, it is a highly misunderstood gas. The problem is not in the gas itself, but in its uncontrolled release into the environment from the energy and processing industries. At normal conditions, carbon dioxide behaves like any normal gas. However, once subjected to temperature and pressure higher than its critical point (31.1deg C and 73.8bar) in a specialized chamber, it transforms into a supercritical fluid with supercritical properties.

Textile dyeing takes place when the dye chemicals are deposited onto the textile material. In conventional dyeing process, we need to dissolve the dyes in water, and then allow the water with dissolved dyes to penetrate into the material and deposit the dyes onto the fibres of the textile. In Supercritical dyeing, the dyes are dissolved directly in supercritical carbon dioxide (CO2), which has the ability to swell and penetrate effectively into the fibres in the textile and depositing the dye molecules onto the fabric. The beauty of this process is that the final dyed textile is dry, thus eliminating the energy consuming drying step. Supercritical CO2 carrying the residual dyes exiting the system can be easily separated by lowering the pressure of CO2 from supercritical to below critical.

DyeCoo, one of the FeyeCon’s spin-off has been very successful in developing the waterless dyeing technology and working with many Multinational corporations to deliver sustainable textile dyeing solutions.

In the end, my answer to the most important question in the universe at that time was “Red, because you can wear it during Chinese New Year”.