Low cost, high throughput quantification of microplastics released from textile wash tests: Introducing the fibre fragmentation scale

Microplastic fibres are found everywhere that researchers have looked for them, from remote mountains to human lungs. However, data is not yet available to facilitate design of low-shedding textiles. Effective use of standard test methods could establish the impact of processing variables on textile’s propensity to fragment or shed fibres into the environment, allowing industry to design and select lower-polluting materials. Three new test methods recommend using the widely accessible accelerated laundering equipment used for colour fastness to wash tests. However, recommended gravimetric analysis of results takes over 8 hours per specimen batch, in addition to specimen preparation, testing and effluent filtration, making analysing test results prohibitively time consuming, and expensive, for many brands. Visual ‘grey scales’ are very commonly used to grade colour fastness test results and this paper proposes use of an equivalent ‘fibre fragmentation scale’ to dramatically increase the throughput of fibre fragmentation testing and reduce its cost without compromising accuracy or reliability. Mean fibre fragmentation scale grades given by sets of 3 observers correlated with gravimetric results at 99% confidence. Subjective grades assigned to test specimens, and photographs of test specimens, had significantly lower variability than gravimetric methods at small, ‘more acceptable’, levels of fibre fragmentation.