The series and the publication Siva Boja are a continuation and extension of the book Ultramarin Ultramarine Outremer that appeared in 2019; they endeavor to document a “colorful black.”

This neutral black is a mixture of colored pigments that results in a colorless hue containing no black pigment. At the same time, the publication Siva Boja also documents the special characteristics and various nuances of the historical green-earth pigment that traditionally forms the basis for the tone incarnadine.