Indanthrone BlueA very dark, semi transparent color, sometimes referred to as Anthraquinone Blue. With a Lighfastness rating of I, it makes a good alternative to the fade prone natural Indigo, which it was originally meant to replace. Indanthrone is a strong mixing color. Series: 7CI Number: NACI Name: PB60Pigment Name: IndanthroneLightfastness: ASTM I ExcellentOpacity: Semi TransparentGrind: Fine