I washed mine. In the bathtub with warm water. You probably want to use a clean rinsing detergent that won't leave any residue. Someone somewhere (probably here) said to use "Sport Wash", which my wife happened to have. It's a thin, clear, unscented detergent in a small orange bottle. There are other 'sports' type washes from the usual brand detergent companies, w/ loads of scents, and that's not what you want. If I didn't have this, I'd probably have used something like 'tide free'.
I spun it in the spin cycle in the washing machine, after hand washing. It was mostly dry after that. Then let it air dry.
No shrinking.