Indanthrene blue RS

Indanthrene blue RS, C.I. vat blue 4, carbon paper blue, blue O, carbanthrene blue 2R, fenan blue RSN, graphtol blue RL, medium blue, monolite fast blue 3R, indanthrene, indanthrone, pigment blue 60, or C.I. 69800, is a synthetic anthraquinone dye. It has the appearance of blue needles with metallic lustre and melting point of 470-500 °C.

When used as a food dye, it has E number E130.

Indanthrene Blue RS was patented in 1901 by Rene Bohn as the first anthraquinone vat dye, one of the dyes with very good fastness to light and washing. It is used to dye unmordanted cotton and as a pigment in quality paints and enamels.

阴丹士林