It is a water-based pigment ink that is non-toxic, lightfast, and waterproof. Unlike alcohol-based marker ink, the ink does not bleed. With Natural Colors, Gold and Silver Color! These opaque felt tip markers can write on a variety of surfaces including plastic, metal, wood, glass, plaster, canvas and more. Paint can be scraped off from nonporous surfaces like glass, etc. but will adhere permanently to porous surfaces such as wood, paper, etc. Water-based pigment ink is non-toxic, lightfast and waterproof. The ink won't bleed through paper (unlike alcohol-based markers) and is excellent for vibrant signs and craft work.