A New Black Pigment with Antifouling Properties

THE problem of providing an efficient black antifouling paint for use on submarines and at the wind and water line of surface ships has been the subject of investigation for some years. Cuprous oxide is considered to be the best antifouling pigment for performance and economy, but it has a strong red colour. Films of paints containing it frequently turn green on immersion in sea water because of the formation of basic copper salts. Attempts to produce black paints with a cuprous oxide base by the addition of sufficient carbon black to retain an acceptable colour after prolonged immersion reduce the antifouling efficiency. Another approach has been to augment black copper compounds, such as cuprous sulphide, which have too low a solubility in sea water, by adding other poisons such as cuprous oxide, mercury salts, or organo mercury or tin compounds, together with carbon black to improve the colour. No fully acceptable solution has yet been found1–4.