Here's a tip I just learned this year after 28 years of teaching. I wish I could have known earlier. For those who like clean boards, take a Puff brand tissue with lotion in it and wipe it over the entire blank blackboard. Then write with chalk as usual and erase with a regular eraser. The trick now is to take a Puff with lotion and wipe clean. The boards have no dust and look brand new. Never do you have to deal with that icky wet sponge routine again!