Stella Blu Brings NTX’s Waterless Cooltrans Coloring Process to Denim
One of the denim industry’s major sustainability challenges and targets is around water consumption. A particular focus is the water used to dye denim its classic indigo hue.
Prosperity Textile’s Stella Blu division is wading into waterless coloring for denim through a partnership with NTX on its Cooltrans technology. Cooltrans colors knit and woven fabrics using transfer printing, which is both less resource intensive and more precise in dye application than conventional methods. The process eliminates the need for baths, drastically cutting down the water used for coloring.
“Both NTX and Stella Blu stand as vital links in the textile industry’s supply chain, with shared commitments to sustainability and innovation to decrease our environmental impact,” said Kalvin Chung, chairman of NTX, on the strategic partnership. “It’s our pleasure to welcome Stella Blu into the NTX ecosystem, and we look forward to collaboratively propelling our shared eco-friendly objectives.”
Carved in Blue spoke with Marco Stefanelli, director of marketing and business development at Stella Blu, about its work with Cooltrans and what to expect next in this partnership.
Carved in Blue: This is not the first time that digital printing is being used for denim. What is different or unique about Cooltrans in the digital printing space?
Marco: Yes, we saw several previous attempts to use digital printing into denim. Most of them had fallen short, primarily due to a lack of scalability, high prices, low resolution and poor hand feel. Cooltrans is addressing all these issues and more. This is not digital, nor sublimation, nor inkjet printing. It is a brand new revolutionary waterless textile coloration technology that creates a unique value proposition. We cannot say how we compare to other waterless technologies, because to the best of our knowledge, they’re mostly specialized for singular material types or fibers. There is no other waterless low carbon printing or dyeing technology that is applicable for any type of material or fiber like Cooltrans.
Carved in Blue: How did your partnership with NTX begin? Why did you decide to link with them?
Marco: Everything started during Covid. In those extremely difficult times, our founder Mr. Koo had the wisdom and vision to remain unshakable and open minded. He met with Mr. Chung, chairman of NTX, who was already successful in the field of sportswear and activewear and was in the lookout to venture into denim. The timing was just right. Both founders decided to join forces as they saw into the future and share the same commitments to sustainability and innovation to decrease the industry’s environmental impact.
Carved in Blue: What is the sustainability reasoning behind Cooltrans? Can you briefly explain the environmental footprint advantages of Cooltrans vs. conventional jeans production?
Marco: Cooltrans can precisely color almost any fabrics, both natural cellulose-based or synthetics man-made without the need for heat, and over 90 percent reduction in water usage without compromising the fabric’s engineered feel or functional performance.
As you know, on conventional denim we have an extensive use of water, heat and chemicals starting from the initial processes of fabric making—dyeing yarns into several indigo baths—all the way down to laundry processes to create that vintage distressed look. With Cooltrans, we are able to completely eliminate these two processes. We start from a white PFD fabric and then the coloration process happens at both sides simultaneously in only one single pass—the front face gets the printed washed look and the back side face gets printed with the twill line or any other pattern the clients desire.
Carved in Blue: Since you have been working with Cooltrans, what, if any, production limits have you seen?
Marco: This is the most difficult of innovation and a brand-new technology. Every week, we learn new ways to get better and more efficient. What separates failure and success is scalability. Given NTX’s experience with the sports and outdoor industry to go to full commercial scale in excess of 1 million, we have no doubt we will be able to scale for denim as well. In terms of colorfastness, we are able to achieve high solidity with same results as reactive dye.
Carved in Blue: On the other hand, what design opportunities has this unlocked that wouldn’t be possible with conventional dyeing?
Marco: This technology opens up extremely exciting possibilities. For instance, we could have a single quality greige and print nearly infinite combination of aesthetics. By doing so, we drastically improve the speed to market with much lower SKUs.
Denim aesthetics today are primarily influenced by the yarn in fabric design. The slub, the frequency of the slubs, the combination of the ring, fiber types/lengths, the weave density, etc. playing a crucial role. Many denim brands today have a material library of over 500 different types just for the sole purpose of achieving a desired aesthetic. With Cooltrans, the aesthetic is completely independent of the fabric base composition. After “calibrating” our process to a particular fabric-base for shades, gradients and finish patterns, we can have 500 different aesthetics on one singular twill type; so the savings for the brands are huge.
Finally, the elephant in the room: indigo. We are all denim lovers here and we all love it, but we also all know how impactful it is on our environment. To eliminate the toxicity is a common goal the industry has been trying to do but never being able to, thus it is fair to argue that brand houses see Cooltrans as very promising to eliminate that toxicity.
Carved in Blue: How does the breathability of the fabric compare to traditional denim?
Marco: There`s no change to breathability. Breathability is a function of construction and material. We use the same dye stuff as any conventional process, just a different physical process. So by default, it would be impossible to impact a performance such as breathability.
Carved in Blue: Could you describe the hand feel of the fabric post-printing?
Marco: The hand feel feels extremely close to a traditional denim. There is no rubbery nor oily feeling after printing. Right after the process the fabric is just a bit stiff and that goes off after a very light rinse wash.
Carved in Blue: Is there any specific advantage of using TENCEL™ fibers on the base fabric for the Cooltrans technology?
Marco: We are seeing great results in the coloring of TENCEL™ fabrics, both 100 percent TENCEL™ and blends. The fibers respond very well to color absorption and saturation. We have been able to reproduce high definition intricate patterns as well as solid colors with extreme precision, whilst retaining the same soft hand feel and drape that everyone knows and loves about TENCEL™.
Carved in Blue: Would other mills be able to use Cooltrans? What would the adoption process look like?
Marco: At this moment, we are not at liberty to divulge specific details concerning its adoption. The battle to fight carbon emissions is a global challenge, so it will be auspicial that other mills will go in this direction. Currently we are the first and sole denim mill possessing this technology.
Carved in Blue: What is next in this collaboration?
Marco: The partnership between NTX and Stella Blu signifies a major advancement in promoting sustainability within the denim industry. Next would be the expansion to our denim mill in Vietnam as we believe in synergizing our respective expertise and resources to collaboratively hasten the adoption of eco-friendly and sustainable practices, mitigating the industry’s environmental impact and crafting a more sustainable future for all.