Blue Wave from Jöst. Compared to conventional melamine cleaning sponges, the Blue Wave sponge differs in its unique waffle. The resulting essentially reinforced structure leads to an enormous increase in service life. With this cleaning sponge, all stubborn dirt on smooth and hard surfaces such as heel marks on floors, pen marks on desks, calcified surfaces, car windows and much more can be easily cleaned with just water – without chemicals – thanks to its eraser effect. Do not use on highly polished surfaces.