Our Chalkboard Crayons are the perfect item for our chalkboard placemats.ÿ They are washable, non-toxic and wipe off our mats with water.ÿ These can be used on non-porous chalkboards but since no one can ever tell for sure, please test these before using on any chalkboard that isn't ours. This 4 pack includes blue, pink, yellos and white.