Permapaque is an opaque marker which is permanent on most surfaces, except for smooth, non-porous surfaces, like glass. This makes this special holiday set perfect for window lettering and drawing! Permapaque is easy to use, so no shaking and/or pumping required. The water-based ink is odourless, smudge free, quick-drying and removable with a wet cloth. Permapaque is not suitable for chalkboards or surfaces that come into direct contact with food or drinks.