Go to Pat Catans or an art supply place and get a document cleaning pad. Its a little cloth pouch/pad with eraser like material inside. As you rub it on the paper, tiny bits of eraser fall out of the sack. The dirt sticks/transfers to each tiny bit of rubber like material and then you just dump the particles in the wastebasket. Works pretty good. I'd use that before I used water. They probably sell them on EBAY too.