Our bamboo lids are custom-made for booni doon. By omitting the conventional plastic liner, our bamboo lids may expand and contract due to the ambient temperature and humidity. We recommend storing your CALM jar in a dry, cool place. If that is not possible, rub a tiny amount of olive oil on the grooves of the lid to help with any wood contraction. Please ensure any oil does not come into contact with the CALM cleansing capsules.