A material suitable for a guest-host liquid crystal device comprises a solution of a liquid crystal material and a pleochroic dye characterised in that the dye comprises at least one anthraquinone compound free from water-solubilising and ionic substituents and having the formula:
wherein each of R and R' independently represents an n-alkyl group having from 4 to 7 carbon atoms inclusive and wherein each of R 2 and R 3 is independently selected from hydrogen and alkyl groups having from 1 to 4 carbon atoms inclusive.