Assessing the contribution of sewing threads to microfiber release during domestic laundering

Environmental science studies from the past decade have emphasized that microplastics in aquatic environments are mostly caused by domestic laundering of synthetic textiles. Although many studies have explored the microfiber release behavior of fabrics washed in laundry, attempts to witness microfiber release from sewing threads, which are an inevitable part of any finished garment, are meager. With this research gap, this study attempted to analyze the potential of sewing threads to release microfibers during washing and the extent to which they can contribute to the overall microfiber release during domestic laundering. The study's findings revealed an average release of 2.65 ± 0.70 (n = 33) microfibers/m from the sewing thread sewn on the fabric during laundering. The sewing process was noted to cause damage to the sewing thread, which led to a comparatively higher microfiber release (∼114%) compared with the sewing threads that were washed before sewing. Among the selected sewing threads, higher microfiber emissions were reported with spun threads, followed by twistless filaments, and twisted filament threads. The results showed that coarser sewing threads with higher Tex values released more microfibers than finer Tex threads. Compared to the 20 Tex spun thread, the 80 Tex spun thread showed a 22-150% increase in microfiber release. In the case of filament sewing thread, a similar impact was noted, whereas the role of twist was found to be efficient in reducing microfiber emission. Compared to the untwisted filaments, the ply twisted filaments exhibited approximately 76% lower microfiber emissions. The findings of this study showed that sewing thread contributed approximately 1.09% of the total microfiber emissions from apparel during laundry.