Washing instructions from inside ball band:

“HAND WASHING: Use lukewarm water and mild liquid soap. Spin in last cycle (no heat or water) of washer if possible, or roll in heavy towel and squeeze. Do not leave in towel. Turn garment inside out before spin drying.
AFTER HAND WASHING: Lay flat on smooth surface away from heat or sun until thoroughly dry. To avoid bleeding of multicolors, place paper towels between layers and replace if they become wet.”