If you value your humidor DON'T rub it down with water! You can maybe get by with doing that once or twice, but if you do it very often you will eventually ruin (read rot) the wood or start to grow some real nasties in the hidden cracks and crevices. Water helps trees grow, water makes cured wood swell, crack, rot, etc. If the humidor seals well a proper sized humistat should be all the humidity you need. If it doesn't seal well add more or bigger humistats. Forget that advice from non-woodworkers about rubbing water on the wood.