The HARIHAR CHEMICALS togather with Fast Colour Bases, form a series of products which are used for production of insoluble azo-colours on cellulosic material such as cotton, linen, rayon, jute, hemp etc. They yield a wide range of yellow, golden, orange, scarlet, red, maroon, etc having good to excellent fastness properties Any Harithol can be combined with any Fast Base to get variety of azoic pigments on the fibre selection of the particular combination to be used in any instance in determinded, in practice, by the shade and fastness property of the resulting dyeing and secondly by the suitability of the combination for use under the proposed condition of application.