We already know that traditional textile dyeing is using a significant amount of water and is highly polluting. In fact, 17-20% of today’s industrial pollution is the result of conventional textile dyeing and there are 72 toxic chemicals in water bodies thanks to the textile dyeing industry out of which 30 are permanent and cannot be removed with treatment. It has been clear for a while that alternative and more sustainable methods have to be developed as people’s consumption habits are less likely to change in the near future.
Air-dyeing
Air-dyeing is today’s sustainable alternative to the traditional fabric dyeing and decorating process. It is using 95% less water and 86% less energy, contributing therefore much less to global warming compared to traditional textile dyeing. It is a clear response to increasing awareness of the environmental impacts of the traditional textile dyeing process.
The inventor of airflow dyeing is Wilhelm Christ. He patented the process in 1978 when the first prototype of the airflow dyeing machine was created. It has been further improved since then and today’s Air-Dye technology has been developed and patented by Colorep – a California-based sustainable technology company.
Air-Dye technology manages the application of color to textiles without the use of water or with the lowest liquor ratio on the market. The water serves as a solvent for dyeing liquor which is mixed with pressure airflow and then sprayed on the fabric. It means the dyeing chemicals directly contact the fabric and penetrate the fibers. There is no post-treatment or finishing required. Since the dye is inside the fibers, the air-dyed fabrics do not leach colors nor fade as easily as vat dyed fabrics. Also, bleach and cleaning agents can’t get it, meaning the colors look richer and last longer. Air-dyed fabrics can therefore be washed at any temperature, with whites or colors, with or without bleach.
The Air-Dye patented textile printing machines allow to color one or both sides of the fabric simultaneously and with independent color control. It can also create patterns on one or both sides or color on one side and patterns on the other side. It means it creates new design capabilities for fabrics.
The moisture-saturated airflow ensures the uniform distribution of temperature on the fabric and in the machine which is a prerequisite for even and reproducible dyeing. The fabric is also much lighter (compared to conventional dyeing) and can be accelerated more quickly to high speeds which results in very short fabric turn times.
The negative side of air-dyeing is that it can be used with synthetic fibers only. However, in 2012 some world-class engineers and apparel experts established ColorZen technology which allows to color also cotton fibers.
You are probably now wondering why have you never heard about this technology before and why are most textile dyeing companies using the old textile dyeing technologies when they are significantly more polluting and harmful to the environment. One reason is definitely a habit or being accustomed to doing so. Waterless dyeing technologies have not been around for too long compared to conventional dyeing technologies and as we know, habits are hard to break. Another major reason is definitely the higher machine installation costs for the waterless dyeing process.
Hopefully, this will change in the not too distant future.
Supercritical CO2 assisted process
Say what?
It is not as complicated as you think.
Supercritical fluid dyeing was first established by German professor Schollmeyer and his research group in the 1980s. Since then, many research experiments have been developed from laboratory to pilot scale.
CO2 is used as a fluid in the dyeing process due to its non-flammability, nontoxicity, and availability. Its critical temperature (31.1C) and pressure (74 bar) are also lower than that of many other fluids. Supercritical CO2 acts as gas at above 31.1C and 74 bar.
This carbon dioxide fluid is being used instead of water in the dyeing process. It is advantageous for dissolving hydrophobic dyes and the diffusion properties of supercritical CO2 can also lead to shorter dyeing times compared to water.
In 2008 DyeCoo developed a waterless dyeing method where they use the power of supercritical CO2 as a solvent for many synthetic and natural dyes. It has many advantages compared to conventional textile dyeing – the already mentioned shorter dyeing time, but also 50% lower operating costs.
CO2 and dyes can be reused which makes this waterless dyeing process also economically feasible and environmentally attractive. Many known brands like Nike, Adidas, and IKEA have been used this method in their textile dyeing.
Now the reasons why it is not yet widely used are the same as for air-dyeing (see above). However, both methods are likely to have a bright future due to their ability to conserve fresh water and reduce waste.