In reply to J1234:
Stick it in the bath. They're waterproof (obviously) and dry very fast. I had a Therarest that leaked slowly - I couldn't find the leak anywhere, even when submerging and compressing the mat. I eventually surmised that it was probably an issue with the valve. Russ from the sadly redundant Escape Outdoors shop in Aber contacted Thermarest on my behalf and they replaced it without question, even though it was several years old. Very impressed with the service.