Blue Cast: Stella Blu’s Marco Stefanelli on How Cooltrans Curbs Printings’ Denim Limitations
Blue Cast is a podcast series from the TENCEL™ Denim team. Each episode features a conversation with a special guest from within the industry or the fringes of the denim community. The following is a recap of episode 412.
In the quest to reduce the impact of denim and create new looks, the industry has experimented with alternative coloring methods. But earlier efforts to use sublimation or rotary printing had their limitations.
As Marco Stefanelli, director of marketing and business development at Stella Blu, explained during our latest episode of Blue Cast, sublimation was only possible with synthetic fabrics. In comparison, the mill has been using NTX’s Cooltrans technology, which has enabled printing to extend to natural fibers including TENCEL™.
Stella Blu has entered a joint venture with NTX, which has helped bring Cooltrans to denim for the first time. Prior to that, the technology was being used for synthetic active apparel for brands like Adidas. “We are the first let’s say precursor of this technology in denim as a mill and we are excited to bring it to the market,” Marco told Lenzing’s Tunca. Kılıçkan.
So far, Stella Blu has tried out the coloration process on a range of natural fibers including cotton, linen, hemp and fabric that is 100 percent TENCEL™ with success. TENCEL™’s strong absorption leads to stronger, deeper colors. “TENCEL™ reacts actually very well to this technology because the color saturation and the color absorption is even better in some cases compared to cotton,” Marco noted.
Cooltrans colors both sides of the fabric at the same time in a single pass, something that digital printing can’t do. It allows for two different colors to be applied without affecting each other or migrating, opening the door for design details.
“The limit is the fantasy because really, there is no limitation in terms of what you can do with the technology,” Marco said.
The process is heatless, which both saves on energy and prevents the stress to fabric caused by heat. Additionally, water is removed from the coloring process and Cooltrans-colored denim looks can skip the usual industrial laundry. They just need a rinse wash after the color transfer.
Cooltrans is versatile, and it can be used on a range of fabric weights—from light 4 oz. textiles to stiffer 14 oz. fabrics. This means that material libraries can be edited, saving resources and costs, while also allowing for broad aesthetic options. The actual printing process is speedy. A solid color can be printed at a rate of 80 meters per minute, while more complicated designs can be finished at 40 meters a minute. These combined factors mean shortened lead times; so far, Stella Blu has found it trims at least 30 days off.
Stella Blu has used Cooltrans to mimic garment dyeing, create patterns and replicate denim looks. For the denim styles, the mill has been able to achieve a vintage denim look and hand feel that is virtually indistinguishable from traditionally made denim jeans.
Depending on what consumers are looking for in their denim, there are some limits with Cooltrans. The process uses reactive dye, which is not as laser friendly. Additionally, the denim will not fade or get worn in marks like normal indigo jeans. A rinse denim made via Cooltrans will stay dark, which gives a continuous clean look that some would prefer while others seek out natural worn looks. However, one problem has gone away, since Cooltrans does not lead to crocking—or color transfer—like conventionally dyed denim can.
“For the diehard denim lover, indigo lover, it might be something that I if I buy something in a raw denim look made with Cooltrans it wouldn’t fade the same way that a traditional indigo [would],” said Marco. “This young generation, they don’t really care, they don’t really want to start all the way from a raw denim and bring it to the vintage wash.”
Listen to the episode here.