Storm's website says that the Shammy is leather "on both sides." I have Master's Wipe-It-Dry Pad which feels like leather, so the Pad and Shammy are probably similar. If you google BowlwithMaster.com, you will find Master's website and a couple of youtube demonstrations on how to clean the Pad. One instructional says to wet the Pad with warm water and rub in a household degreaser with a soft nylon brush. The other youtube demonstration says that you should use a leather cleaner.
I tried the warm water/degreaser method which did a fair job of cleaning. The Pad does not have the same feel after I used warm water. I have a leather cleaner at home, so I may try that next. The Pad still works fine and takes a lot of dirt and oil off the ball.