As soakers are made with yarn which is made of lots of fibers, there will always be air trapped in between them to some degree. Probsbly not as much as wool, but some. I love our acrylic ones as it so easyto care for, and looks so good just out of the machine. And it wworks at night much better than her wool ones, I think becuase she sleeps on a sheepskin and the 2 forms of wool together cause wicking???