Posterman Waterproof liquid Chalkpens are completely waterproof and are designed for indoor & outdoor use. They are ideal for messges on boards outside as they will not wash off in the rain! However, they can still be removed from any non-porous surface with a damp cloth using "Mr Muscle Glass & Window Cleaner" or our "Zig Chalkboard Cleaner".
Ideal for use on: Chalkboards, Whiteboards, Glass, Plastic, Mirror, Metal, Slate and many more!
Safe and suitable for children. Water-based Ink, Non-Toxic & Xylene Free!
Please note: MDF boards which are painted with Chalkboard Paint can sometimes absorb the ink. To avoid staining your boards, we recommend you use at least 3 or 4 coats of paint to seal the board. That way the ink is less likely to be absorbed.