H&M is hoping for a breakthrough in textile recycling.

The Swedish retailer, which has committed to collecting used clothes in stores in an effort to keep them out of landfills and give them a second life, is taking on an issue that’s stymied scientists for years.

While it’s currently possible to mechanically recycle single fiber fabrics such as denim jeans and wool sweaters, a lot of garments are made from a blend of different fibers. For instance, a pair of women’s jeans might be made from a blend comprising 94 percent cotton, 5 percent polyester and 1 percent elastane, to improve fit, style and comfort. When these garments reach the end of their lives, they usually end up discarded in landfills or downcycled into low-value applications like insulation or carpeting.

Read more at Sourcing Journal.