i dont know anything about humidors, but i want to start one. i see boxes with a black thing on the lid. i assume thats where the moisture comes from, but how is it kept moist, do you have to buy new ones when they dry out. i am considering a disposible brand of moisture things advertised on cigarsinternational. it says you can turn any container into a humidor. does it have to airtight? or would that cause mold. i see airtight jars with humidors in them but the wooden boxes arent airtight, right?