Abstract: A liquid developer composition that is suitable for rendering visible electrostatically charged areas which composition contains in an electrically insulating non-polar carrier liquid having a volume resistivity of at least 10.sup.9 ohm.cm and a dielectric constant less than 3, dispersed coloring matter acting as toner particles and at least one anionic polymer that includes recurring units incorporating an anionic group together with a non-polymeric counter cation, characterized in that the cation is a selected from the group consisting of:(1) a cationic group which is a protonated tertiary amine group,(2) a quaternary ammonium group, a phosphonium group or a sulphonium group, and(3) a cationic group containing at least one carbon chain residue comprising at least 6 carbon atoms,whereby the anionic polymer is adsorbed with a net negative charge on the toner particles.

Abstract: A liquid electrophoretic developer composition suitable for rendering visible electrostatically charged areas, which composition contains in an electrically insulating non-polar carrier liquid having a volume resistivity of at least 10.sup.9 ohm.cm and a dielectric constant less than 3, dispersed coloring matter acting as toner particles and at least one polymer comprising cationic groups neutralized with counter anions, the said cationic groups being positively charged groups of metal ion containing coordination compounds.

Abstract: A liquid developer composition for rendering visible electrostatically charged areas. The composition contains in an electrically insulating non-polar carrier liquid having a volume resistivity of at least 10.sup.9 ohm.cm and a dielectric constant less than 3, dispersed coloring matter acting as toner particles and at least one onium salt polymer including recurring units incorporating an onium group together with an anion.

Abstract: A liquid electrophoretic developer composition suitable for rendering visible electrostatically charged areas, which composition contains in an electrically insulating non-polar organic carrier liquid having a volume resistivity of at least 10.sup.9 ohm.cm and a dielectric constant less than 3, pigment particles carrying at least one substance conferring electric charges on said particles, dispersed with the aid of a block copolymer containing one adsorbent group A and at least one solvatable group B, characterized in that said group A represents a polystyrene chain having a number average molecular weight of at least 2,000, and said group B represents a polymethacrylate fatty alcohol ester chain having a number average molecular weight of at least 7,000. The adsorption of said block copolymer to pigment particles is illustrated in FIG. 1.