Discarded mussel shells can be processed into an effective abrasive for denim sandblasting, offering a more sustainable alternative to mineral materials commonly used in garment finishing. The shell-based grit was shown to deliver strong abrasion performance, remain reusable across multiple cycles, and produce high-quality worn effects, while reducing dependence on non-renewable resources and avoiding more toxic chemical or thermal treatments.
- Tests showed the mussel shell grit was less brittle than garnet, allowing it to withstand repeated blasting cycles without rapid breakdown.
- The abrasive required smaller quantities to achieve comparable denim wear effects, as it retained its structure and effectiveness through reuse.
- The findings were detailed in a study by the Materials and Technologies research group at the University of the Basque Country, published in collaboration with MIT.
THE STUDY: The research examined whether waste mussel shells from the food industry could be converted into a viable abrasive material for denim sandblasting. Conducted by the Materials and Technologies research group, the work evaluated abrasion performance, durability and finish quality using shell-derived grit, comparing results directly with garnet and other commonly used abrasives under controlled sandblasting conditions.
- The study focused on shells discarded by the food sector, treating them as a renewable waste stream rather than an extracted mineral resource.
- Researchers assessed abrasion efficiency, grit durability and surface finish using equipment routinely employed in industrial sandblasting processes.
- Comparative tests were designed to measure performance against garnet, the quartz-free mineral typically used for denim abrasion.
THE PROCESS: The process involves collecting discarded mussel shells from the food industry, then washing and sterilising them using thermal treatment before mechanical grinding and sieving. The resulting grit is projected under pressure onto denim using compressed air equipment commonly employed in sandblasting, requiring no specialised machinery or modification to existing industrial setups.
- Discarded shells are first washed and sterilised through thermal treatment to remove residues and ensure the material is suitable for use in industrial sandblasting environments.
- The treated shells are mechanically ground and sieved to obtain grit of controlled size, which can be collected after use and reused repeatedly.
- The prepared grit is applied to denim using compressed air sandblasting equipment already standard in textile finishing operations, without requiring new machines or process redesign.
WHAT THE DATA SHOWS: Tests showed that grit produced from mussel shells was less brittle than garnet, allowing it to retain abrasive effectiveness across more reuse cycles during denim sandblasting. Because the shell-based particles broke down more slowly, smaller quantities were required to achieve comparable abrasion, improving material efficiency while maintaining consistent surface wear and finish quality.
- Researchers observed that the shell-derived grit resisted fragmentation during blasting, extending its usable life compared with garnet under the same operating conditions.
- Reuse tests demonstrated that less abrasive material was needed overall, as the grit could be collected and reapplied multiple times before replacement.
- The durability of the shell particles contributed to stable abrasion results, helping deliver consistent worn effects across repeated denim finishing runs.
THE BROADER VIEW: The findings position mussel shell grit as an example of how industrial waste streams can be repurposed into functional inputs for textile manufacturing. By replacing non-renewable mineral abrasives with a food industry by-product, the approach supports circular economy principles and suggests potential use of shell-based abrasives in other industrial cleaning and surface treatment applications.
- The researchers highlighted that garnet is a non-renewable mineral, whereas mussel shells are a renewable by-product generated in large volumes by global food consumption.
- Using shell waste as an abrasive reduces landfill disposal and lowers environmental impacts associated with mineral extraction and processing.
- The study noted that shell-derived grit could also be suitable for other industries, such as mechanical parts or ship cleaning, using existing sandblasting equipment.
WHAT THEY SAID
We concluded that the grit comprising ground mussel shells was an effective abrasive and sustainable material. It offers the chance to replace other industrial processes currently used to abrade denim, and which have a greater environmental impact or are more toxic.
— Cristina Peña
Researcher, Materials and Technologies research group
University of the Basque Country (EHU)
The fact is that the grit made up of mussel shells responded very well in wearing away the denim during testing, delivering effective abrasion under standard sandblasting conditions.
— Juan Luis Osa
Researcher, Mechanical Engineering
University of the Basque Country (EHU)
