Water soluble pencils that write on most surfaces. Recommended for writing directly on plastics or on the back of plastic-coated photographic papers. Do not stack photographs on top of each other; writing may transfer. Use a separator of glassine or acid-free paper. Will write on metals, glass and ceramics without a barrier coat, too, although this is not generally recommended. Writes well on Acryloid B-72 and Acryloid B-67 base coats. Do not use a top coat as it solubilizes in most liquids.