Dye composition

The present invention relates to novel dye compositions for dyeing cellulose acetate fibres, especially secondary acetate fibres and blends of secondary acetate fibres with other fibres both natural and synthetic. The invention provides a dye composition for dyeing fibers comprising (a) an azo dye of formula (II) or a salt thereof, and (b) an azo dye of formula (III) or a salt thereof. The invention provides navy and black dye compositions, especially suitable for dyeing secondary cellulose acetate fibers, with superior fastness properties than known navy/black dyes. Preferably, the -crystal form of dye (III) is used, which has greater solubility and achieves quicker dyeing than the commonly-used and forms of (III) when dyeing cellulose acetate at 60-95° C. A new method of making the form is disclosed.