Abstract: Compounds of the Formula (1) and salts thereof: wherein: each A independently is N, C—Cl, C—CN or C—NO2; each Ar independently is a substituted aryl group carrying a —COOH group ortho to the azo (—N═N—) group; L is an aliphatic group carrying a —COOH, —SO3H or —PO3H2 group; each Z independently is —SR2, —OR3, —NR4R5 or a labile atom or group; each X independently is —S—, —O— or —NR1—; each R1 independently is H or optionally substituted alkyl; and R2, R3, R4 and R5 are independently H, optionally substituted alkyl, optionally substituted aryl or optionally substituted aralkyl; or R4 and R5 together with the nitrogen to which they are attached form an optionally substituted five or six membered ring, and their use in compositions and inks for ink jet printing processes and ink jet printer cartridges.