University of Minnesota Duluth professor builds machine to recycle worn clothes

A cashmere sweater can go from closet castoff to loose fiber in about 90 seconds at the University of Minnesota Duluth. Abbie Clarke-Sather’s Fiber Shredder does not slice cloth into scraps; it pulls textiles apart, preserving longer fibers that can be spun back into yarn, which is the difference between novelty and real recycling.

That distinction matters because the fashion waste problem is enormous. University of Minnesota sources say 92 million tons of textiles are discarded globally each year, about 17 million tons come from the United States, and only about 15% of textile waste is recycled. In the United States alone, 14.5 million tons are incinerated or landfilled. Against that backdrop, Clarke-Sather’s machine is less a lab curiosity than a test of whether textile-to-textile recycling can work at scale.

Clarke-Sather, an associate professor of mechanical and industrial engineering, has spent about six years developing the machine in UMD’s Swenson College of Science and Engineering and her Applied Sustainable Product Innovation and Resilient Engineering Lab. The device has a provisional patent, and its pitch is straightforward: keep fibers long, keep materials moving, and keep clothing out of the trash stream. The current prototype processes about 50 grams at a time, roughly a hand towel’s worth of material, while the team works with senior design students to make it handle about five times more.

The project started with a very practical request. While Clarke-Sather was at the University of Delaware, where she held a split appointment between civil and environmental engineering and fashion and apparel studies, Goodwill leaders asked for a better way to deal with unsold apparel and extract value from garments that could not be resold. After she moved to Duluth in 2017, she contacted True North Goodwill, which sent a bale of discarded clothing for sorting and testing. That is the unglamorous truth behind circular fashion: the real feedstock is not pristine deadstock, but stained knits, mixed blends and the leftovers of retail.

The machine’s next test is not whether it can shred a single sweater. It is whether it can handle contamination, keep power use low, and deliver fiber quality good enough to compete with virgin and mechanically recycled material in a commercial system. Clarke-Sather wants versions of it in Goodwill stores, thrift stores, recycling programs and brands that want to process their own waste. If that future arrives, the Fiber Shredder could become a quiet piece of infrastructure for fashion’s next act, turning discarded clothing into the raw material of something new.