A new study examined the safety of ozone finishing and its compatibility with recycled fibers.
Some of the denim industry’s greatest innovations have been finishing technologies. Efforts to streamline processes, while reducing the use of chemicals and natural resources are being widely adopted by brands and it is often where they see their greatest environmental savings.
Ozone finishing, which uses ozone gas to achieve bleaching effects, is one of those solutions. The technique is known for using zero chemicals and less water and energy compared to conventional finishing.
Conducted with Devalia consultancy founder Dalia Benefatto, and in collaboration between Nexia Italy, a manufacturer of industrial and textile laundry machinery, and Institute of Intelligent Industrial Technologies and Systems for Advanced Manufacturing, the study concluded that ozone technology is promising alternative for sustainable denim finishing, with positive environmental effects and no ozone release post-treatment.
It also assessed the mechanical and abrasion resistance of treated fabrics and found that mechanical properties of the treated fabrics must be considered, especially for those containing recycled fibers.
The study analyzed three different fabric compositions: 100 percent cotton; 99 percent cotton with 1 percent elastane’ and 71 percent GRS cotton with 29 percent cotton. It tested two ozone treatments—ozone in water without final neutralization and ozone in water with final neutralization.
The fabrics were then tested for the presence of ozone, mechanical resistance, and abrasion resistance using established methods and standards.
The study found that treated samples did not release ozone after treatment. The fabric with recycled content behaved differently, however.
In terms of mechanical resistance, the 100 percent cotton and 99 percent cotton with 1 percent elastane fabrics showed similar abrasion resistance.
The fabric with GRS cotton was less resistant, suggesting that fabrics with a percentage of recycled fibers may require a multi-phase ozone treatment at lower concentrations.
Nexia Italy offers an ozone production system. The company said it would share data from the study with customers to align with recent European regulation requiring that sustainability claims be supported by objective data and the use of the Digital Product Passport. It plans to also recommend to multi-phase ozone treatment for fabrics with recycled fibers.