We've been everywhere in our Zonkers and have had the opportunity to find the best way to freshen them up without causing any damage, fading, or clumping.
1.) We highly recommend NOT using a washing machine to wash your Zonker.
2.) Instead, hand wash in cold water with a light detergent.
3.) Rinse well, being sure to rinse out all detergent.
4.) Lay flat to let air dry (not in direct sunlight) OR throw in a dryer on low heat with some dryer balls or tennis balls, just something that won't let the filling clump together.
5.) Enjoy your clean Zonker!