disodium 6-hydroxy-5-[[2-hydroxy-3-[(2-hydroxynaphthyl)azo]-5-sulphonatophenyl]azo]naphthalene-2-sulphonate

3,5-Diamino-4-hydroxybenzenesulfonic acid double nitrogen, add Sodium hydroxide make show weak alkaline, in order to make molecules of chlorine is hydroxyl replaced, then first and 6-Hydroxynaphthalene-2-sulfonic acid coupling, again with Naphthalen-2-ol coupling.

blue black. Soluble in water for purple to Copenhagen blue, slightly soluble in ethanol for dark purple, not soluble in Acetone. In concentrated sulfuric acid to deep purple, dilution after brown light orange. Dye aqueous solution to join concentrated hydrochloric acid to brown light orange, Join concentrated sodium hydroxide solution for purple.

Standard	Ironing Fastness	Light Fastness	Fulling		Persperation Fastness	Soaping	Water
			Alkali	Acid
ISO	5	7	5	4-5	4	5	5