A surprising new study suggests that discarded mussel shells—usually thrown away as food waste—could help make the fashion industry more sustainable.
Researchers from the University of the Basque Country (EHU), working with the Massachusetts Institute of Technology (MIT), have shown that ground mussel shells can be used as an effective and environmentally friendly abrasive for giving denim its popular worn look.
The research, published in the Journal of Cleaner Production, was carried out in collaboration with a major international textile manufacturer looking for greener ways to treat denim.
Creating faded or distressed jeans has long been a challenge for the industry, both for environmental and health reasons.
In the past, denim was often treated using sandblasting, where fabric is blasted with silica sand under high pressure.
While effective, this method proved extremely dangerous for workers. In many cases, poor protection led to silicosis, a serious and often fatal lung disease. As a result, sandblasting with silica sand was widely abandoned.
To replace it, manufacturers turned to chemical treatments or laser techniques. However, these alternatives can be toxic, energy-intensive, or less effective at producing the desired texture and appearance.
The textile company involved in this study wanted to return to sandblasting, but with a safer and more sustainable abrasive material than the garnet mineral commonly used today.
After exploring various options, the researchers turned their attention to mussel shells, a suggestion that came from the industry itself. Mussel shells are produced in huge quantities by the food industry and usually end up in landfills. Worldwide, around 1.5 million tons of shells are discarded each year.
The process developed by the researchers is relatively simple. The shells are washed, heat-sterilized, ground into small particles, and then sifted to produce a uniform grit. This grit is then blasted onto denim fabric using standard sandblasting equipment already used in factories.
The results were better than expected. The mussel shell grit not only worked well, but in some ways outperformed garnet. It was less brittle, meaning it broke down more slowly during use. This is important because abrasive grit is collected and reused repeatedly in sandblasting. Over time, all grit becomes too fine and must be replaced. Because mussel shell grit lasts longer, less material is needed overall.
The researchers also found that denim treated with mussel shells had a high-quality finish. The fabric achieved the faded colors designers want while remaining smooth to the touch. Unlike some chemical treatments, the process did not damage the feel of the material.
Beyond performance, the environmental benefits are significant. Garnet is a non-renewable mineral that must be mined from the earth, while mussel shells are a renewable byproduct of food consumption. Using them turns waste into a valuable raw material and reduces the need for extraction of new resources.
The team believes this is just the beginning. While the study focused on denim, mussel shell grit could also be useful in other industries, such as cleaning mechanical parts or ship surfaces. Importantly, no special machinery is required, making it easier for industries to adopt.
For the researchers, the work highlights the power of the circular economy—rethinking waste as a resource.
By looking beyond traditional raw materials and considering what society throws away, industries can reduce environmental harm while maintaining high performance. In this case, what’s left over from a plate of mussels could help shape the future of sustainable fashion.
Source: KSR.
