The socks have comfortable "fluff" on the inside. I bought them primarily as in-home slippers, so I felt that 50% wool would be a good compromise and more durable. (I also prefer that sets of socks all be the same color to simplify matching, and life as some wear out sooner.)We do laundry with weak eco-friendly soap and hot water and dryer set on hot. I washed one pair to see the effect. They did shrink. But the material stretches and they still fit my size 9 foot comfortably.