4-Hydroxy-3-(1-naphthalenylazo)-2,7-naphthalenedisulfonic acid disodium salt

Naphthalen-1-amine diazo, coupled with 4-Hydroxynaphthalene-2,7-disulfonic acid.

blu-ray red. For product red is soluble in water, soluble in ethanol in red. The strong sulfuric acid for blue, purple for red after diluted. In aqueous solution to join strong hydrochloric acid wine red precipitate; Add sodium hydroxide into orange brown.

Standard	Light Fastness	Soaping		Persperation Fastness	Oxygen bleaching		Fastness to seawater
		Fading	Stain		Fading	Stain	Fading	Stain
ISO	3	2	3-4	3	1	2	2	1