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       A research team from Materials and Technologies (GMT) has discovered a new eco-friendly material for sandblasting denim. They found that an abrasive material derived from mussel shells has superior abrasive properties compared to other materials used in the textile industry. This method is also more environmentally friendly, as waste is recycled into raw material.
       A major international textile manufacturer seeking to develop a sustainable abrasive treatment technology for denim fabrics has found a solution thanks to a collaboration between a research team from the Faculty of Materials and Technology at the University of the Basque Country (EHU GMT) and the Massachusetts Institute of Technology (MIT). Researchers Cristina Peña and Juan Luis Osa stated, “We have discovered that an abrasive material made from crushed mussel shells is an effective and environmentally friendly abrasive material. It holds promise as a replacement for other industrial processes currently used for abrasive treatment of denim, which have a greater environmental impact and are more toxic.”
       Traditionally, abrasive finishing of denim involved high-pressure sandblasting, which sprayed quartz sand onto the fabric. However, due to inadequate safety and protective measures, workers using this method developed silicosis. Silicosis is a highly fatal disease, so abrasive sandblasting was gradually abandoned by the textile industry. Other methods, such as oxidative chemical treatment and thermal laser treatment, were then adopted. However, these methods proved more toxic and less effective than sandblasting.
       ”Considering that sandblasting itself doesn’t harm workers with proper protection, the brand behind this clothing wanted to reimagine the process, but using more sustainable materials—in other words, more sustainable than garnet (a silicate mineral that doesn’t contain quartz), which is typically used as an abrasive,” explained Penia. Initially, they tried using buttons from old clothes destined for landfills, but it didn’t work. So they decided to look for renewable materials and, on the advice of the textile company that commissioned them, began experimenting with mussel shells—specifically, those discarded by the food industry. “I lived near a bar in San Sebastian called La Mejillonera (meaning ‘mussel habitat’), and we took advantage of that to conduct some experiments with the mussel shells that are typically discarded there.” The process was as follows: the shells were washed, heat-treated to sterilize them, crushed, sieved, and finally, the crushed particles were sprayed onto denim fabric using an air gun. “We found that this method abraded denim very well, more effectively than garnet, which is typically used in sandblasting,” Osa said.
       They concluded that mussel shell chips are less susceptible to degradation than silicate minerals and, therefore, exhibit superior performance. “It breaks less during sandblasting than garnet. This is an advantage. In fact, it takes less mussel shell chips than garnet to wear out the same amount of jeans. In fact, during sandblasting, after the garment is finished, the used chips are collected for reuse. They are collected and reused repeatedly. However, after each use, the chips gradually become smaller, so new ones must be added periodically. Therefore, we found that mussel shell chips are more durable than garnet, so less material is required to achieve the same wear effect,” the researchers explained.
       They also confirmed that sandblasting fabrics with mussel shells produces excellent results. In other words, it produces colors that appeal to fashion designers and consumers, and, unlike other chemical treatments, it leaves the fabric smooth to the touch.
       Another important finding of the Eindhoven University (EHU) study is the eco-friendliness of the abrasive they discovered: “It has a lower environmental impact than traditional and chemical abrasives. For example, garnet is a non-renewable resource, just like shells. Garnet is a mineral that must be mined from nature, while shells are a byproduct. Globally, 1.5 million tons of shells are generated annually due to mussel consumption, and to our knowledge, these shells have not been used until now,” said Peña.
       To make the most of mussel shells, which end up in landfills, the scientific community is working to find new uses for them, and researchers from EHU are leading the effort to find an effective solution. “It was a challenging task, and we spent a lot of time achieving these results, but we are very pleased with the end result. We confirmed the feasibility of using mussel shell abrasives for sandblasting denim, and the results also show that mussel shell abrasives have many other applications; they can serve as a suitable abrasive material and be used in other industries, such as cleaning machine parts or ships. More importantly, no specialized equipment is required. We tested it on machines commonly used in sandblasting processes, and the results were excellent,” explained Osa.
       Researchers from the European Humanities University (EHU) emphasized that this study contributes to the development of a circular economy: “This is an excellent starting point for us to redesign existing production processes. This is not only about achieving more sustainable processes, but also about making more efficient use of the waste generated. This demonstrates that we need to take a broader view of raw material use, consider alternatives beyond those we have traditionally used, analyze the waste generated, and find ways to recycle it.”