Discarded mussel shells from the food industry could soon find a second life in fashion manufacturing. Researchers from the University of the Basque Country (UPV/EHU), in collaboration with MIT, have demonstrated that ground mussel shells can function as a high-performance and more sustainable abrasive material for sandblasting denim.
Sandblasting is a widely used technique to create the worn, faded look that defines many denim garments. However, traditional sandblasting with silica sand has been largely abandoned due to severe health risks, including silicosis. Alternative processes such as chemical oxidation or laser treatments have since been adopted, but these often involve higher toxicity, greater energy use, or less satisfactory aesthetic results.
The research team investigated whether waste materials could replace conventional abrasives such as garnet, a non-renewable silicate mineral commonly used in modern sandblasting. Their solution came from an unexpected source: mussel shells discarded by the food industry.
After washing, sterilising, grinding and sieving the shells, the resulting grit was tested using standard sandblasting equipment. The results showed that mussel shell grit not only performs effectively, but in several respects outperforms garnet. The shell-based abrasive is less brittle, meaning it breaks down more slowly during use and can be reused more times. As a result, less material is needed to achieve the same level of abrasion on denim.
Beyond performance, the researchers confirmed that the aesthetic and tactile qualities of the denim remain high. The sandblasted fabric achieves the colour gradients and worn effects valued by fashion designers and consumers, while maintaining a smooth surface finish. Unlike some chemical treatments, the process does not compromise the hand feel of the textile.
From a sustainability perspective, the benefits are clear. Mussel shells are a renewable by-product, while garnet must be extracted from the earth. Globally, around 1.5 million tonnes of mussel shells are generated each year, most of which currently end up in landfill. Repurposing this waste stream aligns strongly with circular economy principles and reduces reliance on virgin raw materials.
While the study focuses on denim production, the implications extend further. The researchers note that mussel shell grit could also be suitable for other sandblasting applications, such as cleaning mechanical components or ship surfaces, without requiring specialised equipment. This opens up opportunities beyond fashion, particularly for product designers and manufacturers exploring bio-based abrasives and low-impact surface treatments.
The research highlights how rethinking waste can lead to material innovations with real industrial relevance. For designers working at the intersection of sustainability, materials and manufacturing, mussel shells offer a compelling example of how circular thinking can reshape established production processes.
Source: University of the Basque Country
Photos: Egilea Juan Luis Osa