Neon Fluorescent Liquid Chalk Marker pens are ideal for all kinds of decorating and writing on glass art ,windows displays to menus, LED board, blackboard non-porous surfaces. Pop art Liquid chalk use pump style nib will help you minimum waste. For first time use please shake well with cap on and up-right remove cap, press nib for 30 seconds or even longer until nib fills with ink and also can take out nib to check whether the ink come through or not. After use recap tightly after use and store in horizontal position. For how to clean: Using dry cloth to clean for glass surface, and use damp cloth to clean for wood blackboard non-porous surfaces.