Abstract: A liquid developer system for use in electrostatic imaging processes of the positive toner type comprises toner particles micro-dispersed in a carrier liquid and at least one charge director compound soluble in the carrier liquid, wherein the total amount of charge director compound is associated with the toner particles and essentially no charge director compound is present in the carrier liquid. Especially useful charge director compounds are those which have been reacted with at least about one molar equivalent of at least one acid containing at least one organic moiety, the acid being effective in that the reacted positive charge director compound increases the short-term charging of the micro-dispersed toner particles as compared with charging when the same molar amount of unreacted charge director compound is used. Positive charge director compounds reacted with acid are e.g. those of the general formula RSiX.sub.