“Milk casein” fiber was used in many garments and household items in America and Europe during the 1930s and ’40s. It’s made using a process that is similar to rayon/viscose (derived from wood pulp), but because it’s a regenerated protein fiber, it reacts like wool. Historically, it was used as a wool-alternative, advantaging soldiers on the front lines in times of wool scarcity. However, it fell out of use after WWII ended and newer, cheaper synthetics such as nylon grew in popularity. The cotton/milky fabric improves skin comfort, moisture absorption and is naturally antibacterial.