2,7-Naphthalenedisulfonic acid, 4-[(1-amino-5-hydroxynaphthalenyl)azo]-5-hydroxy-, disodium salt

4-Amino-5-hydroxynaphthalene-2,7-disulfonic acid?diazo, and 5-Aminonaphthalen-1-ol?in acetic acid medium coupling.

green light blue. Soluble in water for purple. The strong sulfuric acid in blue, diluted began to change color, and then into a purple. In water solution to join hydrochloric acid colour and lustre is basic unchanged; Add thick sodium hydroxide solution for orange.

Standard	Light Fastness	Soaping		Persperation Fastness	Oxygen bleaching		Fastness to seawater
		Fading	Stain		Fading	Stain	Fading	Stain
ISO	4	3		2	2		3