This color contains the following pigments:
C18H12N2O6, sodium salt
Lithol Rubine is a deep transparent red dye, generally slightly bluish, that is laked as a salt with sodium or calcium to form a pigment. PR57 is the sodium salt, and has a more bluish tone. PR57:1 is the calcium salt, and is the most widely used. Lithol Rubine makes clean pinks when tinted. Sources vary greatly in hue and transparency. Lithol Rubine has high tinting strength.
Lightfastness is considered only fair to good. Superior products are available when lightfastness is paramount. Where greater lightfastness is needed in process color printing, the more expensive pigment PR184, a Naphthol AS pigment, is often substituted for Lithol Rubine.
Lithol Rubine is not considered toxic. It is used in food, drugs, and cosmetics, such as lipstick. It can be used in art materials intended for children.
Lithol Rubine pigments (especially the calcium salt PR57:1) are widely used in inks, paints, plastics, and textiles. Lithol Rubine is widely used as magenta in process color printing.
Dioxazine Violet is transparent and has very high tinting strength. It is a staining pigment, very dark valued when it is used at full strength. Concentrated, it paints out nearly black, but it mixes with Titanium White to form bright, opaque tints of purple. PV23 produces slightly redder shades than PV37. Because the hue can vary with the conditions of preparation and grinding, it may be offered in red shade, blue shade, and so forth.
Dioxazine Violet has good lightfastness. There may be some concern about it fading or shifting in color in tints and washes. Some artists have reported that PV37, a molecular variant, is more lightfast than PV23.
Two molecular variants of Dioxazine Violet, PV23 and PV37, are available. They have similar properties, but mix slightly differently.