tetrasodium 5,5'-[carbonylbis[imino(1-hydroxy-3-sulphonatonaphthalene-2,6-diyl)azo]]bisnaphthalene-1-sulphonate

5-Aminonaphthalene-1-sulfonic acid (2 Moore) diazo, coupled with N,N’-bis(4-hydroxy-2-sulfonaphthalene-7-yl)urea.

blue-ray red. Soluble in water for product red, soluble in ethanol is shallow dark pink. The strong sulfuric acid for purple, diluted for pink. The dye solution to join strong hydrochloric acid have article red precipitate; Add thick sodium hydroxide solution for orange brown.

Standard	Acid Resistance	Alkali Resistance	Light Fastness	Soaping		Water
				Fading	Stain	Fading	Stain
ISO	4-5	4-5	2	1-2		1-2