Switzerland’s Swicofil uses milk fibers produced in China to make fibers that it claims are “smooth and soft.” CEO Beda Ricklin, tells Phys.org his company’s milk fiber socks are “like silk.”
Milk fibers are made from the protein casein, which is separated from sour milk. It was once a popular subsistute for wool, but were supplanted by cheaper synthetics like nylon. Unlike past iterations of milk fiber, which used formaldehyde, today’s milk-based fibers are strengthened with the chemical binder acrylonitrile.
Germany’s Qmilk was founded by Anke Domaske after her stepfather developed skin allergies to many commercial fabrics. “When I first heard about milk fiber, I was very enthusiastic, because milk is natural and healthy,” she says. “But when I found out that the manufacturing process uses lots of chemicals, I was very disappointed.” Qmilk’s fibers are made without chemicals and use waste from German dairies, she adds.
Cost remains a limiting factor, however. Ricklin says milk fiber costs $25-35 per kilogram, compared to $1–2 for polyester.