Simply Remarkable Waterproof Chalk Pen to Write or Draw Custom Labels, Tags and More, White Liquid Chalk Marker, 6mm Chisel Tip Waterproof chalk pens won't rub off when in contact with moisture - like condensation from a drinking glass, or rain! Dust-free liquid chalk, for the look of chalk without the smudges or mess Write on any non-porous surface including chalk labels, mirrors & glass, and metal To remove, simply spray with an ammonia based cleaner like Windex To use: shake pen upright for 10 seconds, remove cap and press the tip onto paper or label until ink comes down - this may take several seconds