Mochitsuki Prep, Pounding, and Cleanup Start water to boil. Rice must be rinsed at least 3 times for the mochi to turn out bright white. If insufficiently washed, the mochi becomes slightly yellow. In a zaru (sieve), the water is drained completely. Fill the usu with the hot water to wet the wood deeply. Empty the usu immediately prior to pounding. Preparing the rice takes approximately 40-45min. Taste a few grains every 5 minutes from the 30-minute mark. When the rice is soft all the way through, it is ready. Overcooking the rice causes the mochi to be hard. The rice is ready to pound. Put the rice in the usu. The rice is smashed using the kine or bo. This smashing does about 80% of the mochi prep. At this point, the pounding begins. Cleanliness is key. Both the usu and the pounding implements need to be thoroughly cleaned and all rice in cracks carefully removed.