Posca paint markers use vivid, opaque ink that can write on virtually any surface, including paper, photos, glass, wood, terracotta, porcelain, plastic, fabric and metal. The paint ink can be scraped off from nonporous surfaces like glass but adheres permanently to porous surfaces like paper. It shows up well on both light and dark surfaces, and once dry you can write over it with another Posca marker without smearing or showing through.