First used to address the troublesome issue of back-staining, the mark of a low-end product, ozone is a powerful oxidising agent that is widely considered more sustainable than conventional chemicals. New developments in machinery and chemicals suggest that it has yet to reach its full potential.

Ozone has become the go-to solution for laundries seeking more sustainable solutions. In the past 15 to 20 years since it was first introduced, it has led to significant savings in water and chemicals. From its initial use as a cleansing agent to lift excess indigo, eliminate back-staining of the weft and pocketing, it has gradually evolved to provide nearly fully ‘bleached’ effects. Bleach is not, however, a term the industry favours as one of the key advantages of ozone is precisely to avoid the use of hypochlorite.

“I don’t like to talk about ozone as a bleaching process because it is much more than that,” says Fernando Cardona, Jeanologia’s Brain Box Team manager. “Ozone is a technology that optimises our processes, reduces water consumption and the use of chemicals and eliminates hazardous ones. It helps speed up processing times and increases productivity. With ozone it is possible to clean, it is possible to get abrasion effects and, yes, it can fade down colour, without using water. When these options are combined, ozone delivers huge eco-efficient benefits,” he tells Inside Denim.

The Valencia-based company’s ozone processing machines, G2 and G2Atmos for garment finishing, and G2 Dynamic for fabric finishing, apply the gas in dry conditions. They are designed to be safe for workers as a security system locks the door when the presence of ozone, a toxic gas, is detected inside the machine.

Dry, humid or wet 

Ozone is applied in three different conditions – on dry, humid or wet items of clothing, directly in a washing machine or tumbler. “In a dry tumbler we can work with garments in dry, wet or controlled humidity conditions to achieve different effects,” says Mr Cardona. Ozone can also be dissolved in water, though it is said that controlling the level of ozone and its homogenous diffusion is more complicated in this case.

The ozone-based technologies developed by Tonello are all made for applications inside washing machines. There are two reasons for this, says Alice Tonello, marketing manager for the Vicenza-based company. “The first is safety. Our washing machines are equipped and prepared to perform treatments with ozone without any possibility of gas leakage,” she says. The second is a technical reason. “After the application of ozone on garments, they need to be neutralised through a chemical wet process.” Once the ozone is completely neutralised, an operator can handle the garments without risk, and presumably, no ozone residues are left on the garments. “The presence of residues could further oxidise the garments which tends to give them yellowish stains or smudges, and they wouldn’t even be safe for sale,” she points out.

Tonello is investing in R&D to further develop and expand on its ozone solutions. Its patented OBleach process is said to improve aesthetics by delivering authentic and bright ‘bleached’ effects “using only ozone”. O-zone technology, another new development, is a static cabinet that, again using only ozone, makes it possible to obtain “unique and customisable aesthetics, such as sun-faded looks, localised discolouration or ombre effects,” she says.

“Ozone is part of a general trend to reduce water and chemicals use in denim finishing,” Vittorio Della Valle, technical manager at Nexia Italia, tells Inside Denim. “It reduces steps during treatment, helps gain time and is a fast, powerful and eco-sustainable technology.” The company, founded in 2015 and based in Rosà, in Italy’s Veneto region, acquired laundry specialist Defranceschi, and manufactures ozone generators along with washing and dyeing machines.

Nexia has developed a system in which a single ozone generator can power three to four machines at the same time. The fully automated equipment provides a safe working environment, and a certified catalyst prevents ozone from escaping into the outside air, guaranteeing zero emissions, the company states. Mr Della Valle points out that three conditions are necessary to achieve a stable system and consistently repeatable productions: “Constant oxygen concentration of the inlet gas, constant humidity of incoming air, and stable temperature of the cooling water in the system.” He sees ozone processing as continuing to grow as brands request that their suppliers reduce water and chemicals usage. “Our ozone technology leads to important reductions in water consumption (about 50-60%), energy (about 30-40%) and chemicals (85%) normally used during the washing phases. It also helps reduce water pollution,” he says.

For laundries looking to achieve a higher level of abrasion, the company has developed a patented abrasive layer that can be inserted inside the drum. “No Stone scrapes the fabric while ozone bleaches it without chemicals, leading to less rinsing,” he says.

Ozon Denim confirms growing interest for ozone machinery in laundries. “It helps reduce water usage, chemical consumption, and is generally more sustainable for the world,” says Aslan Kenan Yagcilar, marketing and technical manager for the Istanbul-based manufacturer of ozone machines. Despite progress in machinery, he says that processing times remain more or less the same as that of other bleaching methods. But as ozone generators become more powerful and compact, they may also become faster, he says.

Innovation in ozone

A relative newcomer to ozone processing machinery, Wiser Wash has developed a patented technology that calls on artificial intelligence. Its algorithm-driven equipment is said to reduce variations, decrease cycle duration by 40% and achieve better bleaching results through homogenous ozone infusion, for an overall increase in production capacity that it says can reach 66%. The company’s newest machine, Wox, combines an ozone drum and generator with advanced data management. In 2021, it won a Chicago Atheneum Good Design award. Wiser Tech, the digital services branch of the US and Turkey-based company, contributes to increased efficiency and productivity while also providing predictive maintenance. Wiser Wash machines are currently operating at the facility of Musa Çakici, the company’s business development director, in Turkey, at Arvind in India, Elleti in Europe and Phong Phu in Vietnam.

Nexia Italia is working on developing higher performance machines that would consume less energy and need less air. The company is planning on introducing next-generation machines at ITMA 2023 in Milan. It has also joined a scientific research programme to investigate possible health concerns related to ozone. Devalia, a consultancy founded by denim industry expert Dalia Benefatto, is the project lead and is working with the Institute of Intelligent Industrial Technologies and Systems for Advanced Manufacturing - National Research Council of Italy (STIIMA-CNR) of Biella.

“Ozone is widely used in agriculture, in the food industry and in hospitals. But no sector uses ozone in the concentrations that the denim industry uses,” says Dalia Benefatto. “After processing, ozone (O3) reverts back to oxygen (O2), but a certain a certain amount of by-products could remain in the fabric,” she says. They may react later on, she surmises, and could have an impact on fabric longevity and on skin. “All assumptions are open, but as there is no official testing protocol within the industry, and no third-party verification, we don’t know,” she says. As ozone usage increases, she is concerned that the industry should not make the same mistake it did with sandblasting. Had it been used in the right conditions, it is thought that it would not now be banned. The goal of the research programme is to create a globally recognised scientific protocol for testing the presence of ozone. It may also include stricter safety regulations for ventilation.

Ozone is a toxic gas and its handling obviously dangerous. This raises the question of how sustainable it is compared with other oxidising agents. Is ozone better than bleach? Are critical safety protocols respected throughout the industry? 

Boosters and alternatives

Like many textile processes, ozone is not without setbacks. In some instances, it generates a greyish cast, which requires a new set of operations to revert to blue. At times it creates a fuzzy surface texture that, again, will call for an additional biopolish. Controlling the degree and reproducibility of discolouration seems to be a delicate matter.

The limitations of ozone applications have inspired chemicals suppliers to develop new solutions. These address some of the shortcomings of the gas or offer alternatives for companies that have put off investing in new machinery in the past couple of years when business-as-usual was put on a hiatus.

Oz-One Powder is Officina +39’s solution for laundries that have not yet invested in ozone equipment. Part of the company’s suite of Aqualess Mission products, it is used in waterless conditions and does not require special machinery or safety measures. “This product is not ozone, but an oxidising agent that produces results that are better than potassium permanganate (PP) and hypochlorite. It is a smart replacement for those conventional and harmful chemicals,” says Andrea Venier, Officina +39 CEO, who insists “there is no excuse not to phase out PP and chlorine”.

Kaiser Tekstil’s new Lava Con DOZ is presented as an ozone activator that bypasses the gas’s limitations with regards to bleaching. An “ecological replacement” to potassium permanganate and sodium hypochlorite, it is described as “worker-friendly”, formulated without toxic chemicals and can be neutralised with a simple detergent wash cycle after application. “It is the future of ozone bleaching,” says Kaiser marketing manager Ezgi Nur Ondas. “It removes ozone’s shortcomings, improves its effects and can achieve the very light shades that ozone cannot typically attain alone.” 

Jeanologia is currently working with its customers to develop a substitute for pumice stones by pairing its G2 technology with Atmos08, a chemical booster. “This combination makes it possible to obtain the abrasion results and colour fade-down of traditional stone washing, but with a brighter and cleaner look,” says Mr Cardona.

Lumia, a patent pending treatment by Soko Chimica, is not just a substitute for bleaching, but a completely different process which works in combination with ozone, says Luca Braschi, denim laundry expert and consultant for the Florence-based company. Originally developed as an alternative to potassium permanganate (PP) and hypochlorite, the company has found that “it has much more potential than we initially thought,” he tells Inside Denim.

The key advantage of Lumia is that it works with ozone in dry conditions and as opposed to bleach and PP, does not react on the fabric until it is activated by ozone. It is thus safe to use. Another plus is that it will not corrode metallic components. “Most alternatives will oxidise immediately. Lumia simplifies production planning,” he says. “Lumia exalts abrasion better than bleach, and creates deeper salt and pepper effects.” It can eliminate the need for pumice and reduce enzyme processes. And, the fabric will have not undergone as many aggressive treatments as usual.

Soko Chimica has extended its patent application for Lumia to several countries as it believes it is a game-changer in denim finishing. “At Soko, we seek to develop sustainable processes that perform better than conventional ones. Not less so. Not almost the same. Better,” he says. 

A bright future 

Ostensibly, the possibilities of ozone are poised to expand well beyond cleaning. Under pressure from brands to reduce their environmental footprint, laundries are investing in the technology. “Since the launch of the G2 systems, we have seen huge expansion, and we think that the product has not yet reached maturity,” says Fernando Cardona at Jeanologia.

It remains that the gas, like any oxidising agent, is toxic, and it does appear to be tricky to obtain consistency from batch to batch. Suppliers, as seen, are busy addressing these issues, and chemicals companies also intent on unlocking new oxidising options. These efforts combined may yet make this technology a true alternative to bleach and PP.

Jeanologia’s G2 Dynamic device is designed to treat fabrics; it is a complement to the company’s two other ozone application machines made for garment processing, G2 and G2Atmos.  
Photo: Jeanologia

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