Richard Of York Gave Battle In Vain: colour pigments

Let’s start with red, or should I say reds….

red, the color of blood, fire and wine….. life, danger and vitality

Alizarin crimson (Alizarin madder lake)

About: Madder lake was made from the European madder root, Rubia tinctorum.  Since the 1850s (approximately) it has been made synthetically– under the name alizarin– with an identical chemical composition, but a superior clear transparent tone and lightfastness and by manipulating these chemicals, a range of shades has been made from scarlet to ruby.

Pigment: Roots of the madder plant are dried, crushed, hulled, boiled in weak acid to dissolve the dye, and fermented to hydrolyze anthraquinones from the glycosides. The extracted dye is made into a pigment by dissolving the dye in hot alum (aluminum potassium sulphate; AlK(SO₄)₂ · 12 H₂O) solution, and precipitating pigment with soda or borax. Synthetic alizarin lakes are prepared by reaction of alizarine with aluminum hydroxide.

 In art: Alizarin lake colors are permanent to light and to the gaseous atmospheres of urban areas. However, when mixed with ochre, sienna and umber, they lose their permanence, and when mixed with blacks or oxides, their permanence is not affected at all. Excellent as a glazing color over a dry surface. Alizarin madder lake  is a coal-tar color, and in permanence exceeds the natural product, which in contrast ages more gracefully than the artificial.

For more information see http://jcsparks.com/painted/pigment-chem.html