Most consumers have only a vague notion of the repercussions of the use of pumice in denim stonewashing. For the industry, these volcanic stones remain a gold standard, and are unmatched in their ability to achieve what is considered authentic wear and tear. The long-established practice is nonetheless increasingly being called into question, as alternative solutions come closer to reproducing the coveted look and feel of real stones.
It is the look that everyone is said to want. The so-called salt and pepper effect that denotes authenticity and that pumice stonewashing delivers. But for anyone sensitive to environmental issues, the impact of the continued use of volcanic rocks may come as a surprise. On the grounds of the impact of the mining, transportation, handling and disposing of pumice stones, many might have expected them to have gone the way of the dinosaurs by now.
A natural, though not renewable, resource, pumice handling and use generates considerable pollution in denim finishing processes, from the front to the back end. The transportation of these heavy loads contributes to greenhouse gas emissions. Their handling is time- and space-consuming. Their abrasive properties not only degrade jeans but also washing machines. As they break down into finer particles and dust, they require numerous rinse cycles to clean garments, and they generate difficult-to-manage sludge and effluent.
From semi-synthetic or synthetic stones to various abrasive materials, numerous alternatives to pumice have been developed. They all claim to release cleaner wastewater, have a longer life span than volcanic rocks, can be recycled, and reduce maintenance and handling. But none claim to achieve the exact, like-for-like effect of pumice. This is where new research and development is called for, and where enzymes, commonly used to enhance efficiency, are seen as instrumental.
Among the many alternatives to real stones, some contain actual pumice dust. This is the solution that Turkish technology provider Baytech chose for its patented Hand Made Stones (HMS) that are made from 60% pumice dust, sourced from mining companies, and sealed in biodegradable polymers. Invented by Yavuz Baykan, who founded Baytech in 2016, they are said to offer similar abrasion to traditional stones but break down substantially less, meaning the sludge in waste streams is largely eliminated and the stones last longer. They are said to reduce water usage by between 20% and 30% per load, and further savings are achieved by reducing rinsing after processing.
In a collaborative effort with fellow Turkish partners Baytech and Kaiser Tekstil, Ereks-Blue Matters has developed two “eco stone” wash recipes that combine HMS stones with enzymes. The new process is now used in 25% of its production, and it intends to increase this proportion to 50% of production during 2022, with all new products to be developed without the use of pumice. “We have to say that replacing an iconic and well-known product such as pumice is not easy,” the production and wash platform tells Inside Denim.
EcoDenimStone, an alternative to pumice developed and patented by Turkey-based Nesrin Koçak and her son Berkay Koçak, is said to combine “geological engineering, chemical engineering and occupational health and safety expertise”. The company is careful to protect its IP and does not give any further indication of its composition. But pumice, says Mr Koçak, “is a natural rock that contains many minerals. It is not just the rubbing of the pumice stone on the denims that gives the worn-down look. The minerals in the pumice stone are released by friction and help wear and age denim.” In other words, he says, “no alternative product can replace pumice.” The company says that EcoDenimStone lasts 100 times longer than pumice and can be used in conjunction with enzymes, ideally the water-free sort, for a more sustainable result.
Turkey-based Kaiser Tekstil introduced a set of brightly coloured synthetic F-Stones in early 2020. “In our lab, we have been using the same stones for a year now. They have been in operation for more than 7,000 washes, and may last even longer,” Kaiser Tekstil marketing manager Ezgi Nur Öndas tells Inside Denim. To achieve the best results, she says it is recommended to combine them with enzymes, such as the company’s water-free Lava Cell NSY. When they are no longer effective, Kaiser will take the F-Stones back to recycle them.
Westex, based in Istanbul, claims that its Westex Stones have better abrasive characteristics than natural pumice and can withstand up to 2,000 washes. They are said to reduce water, energy and labour costs by eliminating the need to remove sand residues. As synthetic stones do not absorb chemicals, wastewater treatment is less of a problem, the company says.
At PV Denim in Milan, Blue Jeans Lavanderie Industriali presented a series of synthetic abrasive materials. “We have been trialling all sorts of different configurations, including cubes, spheres and hexagons, and we have found that a 16-sided shape gives the best results,” says company general manager Alberto Rossi. Once exhausted, the stones can be regenerated by the company’s partner in the development process. Using these alternatives in the first six months of 2021, the company says sludge ratio decreased by 30% compared with 2020.
Jecostone, a concept developed by denim industry veteran Floriano Arcaro in collaboration with Mario Cocci and Itexa, a maker of abrasive non-woven materials based in Luzzara, Italy, has taken another route to create an alternative to pumice. The company spent several years creating the two plastic-coated abrasive resin solutions it launched two years ago. Jecostone is a liner designed to be installed in the drum of industrial washing machines, and is said to withstand 100 cycles. Jecorocks are abrasive pads measuring 8 cm in diameter, lasting 60 cycles.
“It is only a matter of time before pumice stones are banned,” Floriano Arcaro tells Inside Denim. He insists that Jecostone products are not only an alternative, but are truly a new product in that they don’t generate the grey effect that pumice dust leaves in treated clothing. “We believe we have a better solution as there is no modification of colour and our process is much safer for the fabric,” he says. Mr Arcaro points out that in the past, denim fabrics were very resistant, and that this is no longer the case. “Pumice can be a problem on delicate or elastic fabrics,” he says.
To boost their effect, Jecostones can also be combined with enzymes, as Mr Arcaro, like many in the industry, concedes that no synthetic abrasive material will achieve the exact same look as pumice. But he says: “Our abrasives reproduce the signs of normal use of a pair of jeans; it is as close as you can get to the real thing.” Less damaging to washing machines and to garments, its solutions are said to be a good option for knitwear.
Launched in 2015, Tonello’s NoStone system is also based on an abrasive drum liner, developed in three versions. The Vicenza-headquartered company says it is operator-friendly in that it is lightweight, easy to handle and removes the need to load and unload stones from washing machines. “With NoStone, our customers can finally say goodbye forever to trolleys and bags full of stones, always in the way and needing to be stored in large spaces in the laundry. The NoStone is thin and stackable when not in use,” says marketing and R&D manager Alice Tonello. She believes it gives the same look as traditional stonewashing while requiring less water because it eliminates the need to rinse garments to remove sand and dust.
Tonello recently introduced a new easy-lock feature that further speeds up time spent installing and removing the NoStone liners. “This allows our customers to switch from one process to another, depending on their needs, making their lives easier,” she tells Inside Denim.
British company Xeros Technology is the inventor of XOrbs, patented polymer beads with various cleaning and decontaminating properties. It has recently turned its attention to denim and has developed a drum- and bead-based stonewashing process known as XTend. The company has developed a special drum, XDrum, equipped with a built-in storage compartment, which automates the distribution and retrieval of the polymer beads. The drum can be integrated into new machines or retrofitted into old ones. A valve in back of the drum releases XOrbs and a herringbone-shaped device inside the lifter guides them back into the storage compartment after washing, says Mike Ferrand, Xeros Technology managing director for commercial products. This, he says, makes it possible to control the deployment and harvesting of the XOrbs, so no handling is required in production.
The company has developed special XOrbs that are larger and denser to increase their abrasive properties. “XOrbs hang onto chemicals or enzymes and distribute them evenly across the load. This makes it possible to achieve an even, consistent and reproducible finish. XOrbs also adsorb excess dye, and will capture remaining indigo to avoid back staining,” says Jamie Harrison, Xeros Technology licensing director. The beads, which can be used in combination with enzymes to enhance their effect, need only be changed twice a year, the company has found. They are never handled and can also be recycled.
Xeros Technology has partnered with Ramsons, a washing machine manufacturer based in India, which makes the drum and equips denim finishing machines with them. ABA Group, in Bangladesh, has recently set up nine Xeros-enabled Ramsons denim finishing machines in a new facility, including eight 5,000 litre capacity machines that can process up to 200 pairs of jeans at a time.
Mechanical and chemical abrasion
Obtaining the authentic stonewashed effect, without pumice, is possible, or nearly possible, but requires a combination of processes, as denim industry consultant Luca Braschi tells Inside Denim. Many different parameters are involved, he says, depending on the look you want to achieve. “Synthetic stones alone will not get you the right look, but need to be enhanced with enzymes,” he says. Soko Chimica’s newest product, Lumia, is designed specifically for that. A dry ozone-based pre-treatment process, it enhances, or as company CEO Matteo Urbini puts it, “highlights” abrasion and reduces the need for potassium permanganate (PP) and bleach. “It is now time to stop using real stones, and it is time for enzymes to play the main, not the secondary, role,” he says.
The combination of mechanical abrasion, provided by synthetic stones, and chemical abrasion, delivered by enzymes, is the best solution, confirms Luigi Lovato, founder and CEO of Elleti Group. At Pakistan-based Soorty, the new Zero Stone concept also makes enzymes and chemicals play the principal role in denim finishing as part of its Smart Blue Technology.
Crescent Bahümàn (CBL), in Pakistan, has tested a number of synthetic stones. None give the “ditto effect” of real stones, says Zaki Saleemi, CBL’s group vice-president, who adds: “I am for eliminating pumice and switching to other solutions, including enzymes or nebulisation processes, if we can get a result that is 80% to 90% close to the real stones.” He agrees that there is no single-tiered solution to replace pumice and obtaining the desired result often requires tweaking different parameters. “It fundamentally starts with the fabric, which needs to be adjusted to improve output whatever method is used,” he tells Inside Denim. “Some fabrics are laser-friendly, or better for wet or dry ozone. It’s always a combination of both the process and the fabric.”
Then there is the issue of time, and its impact on cost. Real stones are said to achieve the desired look the fastest. Though synthetic stones last longer, can be recycled and lessen the cost of wastewater treatment, they require more time to achieve the desired result, and will need a booster. The consensus is that alternatives to pumice can reach 80% or 90% of the “real thing”. As always in fashion, looks count. What some might have thought to be just a stone’s throw away, the elimination of pumice, is turning out to be an uphill task.
Launched in 2020, Kaiser Tekstil’s synthetic F-Stones are said to have very high durability, in addition to being recyclable. This, the company says, means that no stones go to waste.