Waterproof Woodcraft Liquid Chalk Pens are designed for external or internal use. These are waterproof and will not be washed off by rain or little fingers! However; they are easily removed with Mr. Muscle kitchen cleaner from non porous surfaces. Please note that chalkboard / blackboard paint is slightly porous. We only recommend EaziWipe TM chalkboard for these metallic pens. Our Metallic Chalkboard Pens are perfect for all interior and exterior signage. They are also suitable for use on glass and any other non-porous surface, Outline your text in black when used on glass. These markers will provide bright solid metallic, shiny colours and will give an outstanding look of excellence to any signage. Sold in a pack of 8 metallic pens, 2 Emerald, 2 Sapphire, 2 Morganite, and 2 Amethyst. Water-based pigment ink