Two colours dominate Duccio’s altar painting: the gilding and the blue of the Virgin’s robe. The gilded surfaces were first prepared with several layers of red bole, a natural pigment containing iron. The blue robe is painted in high-quality natural ultramarine, with the shadows hatched in carbon black.

The skin and flesh tones were painted in green earth and then overpainted with pink and white which faded with age so that the green colour is more prominent now than was originally intended (1).

References

(1) Dillian Gordon, Duccio di Buoninsegna, ‘The Virgin and Child with Saint Dominic and Saint Aurea, and Patriarchs and Prophets. In David Bomford, Jill Dunkerton, Dillian Gordon, Ashok Roy, Jo Kirby, National Gallery Catalogues, The Italian Paintings before 1400′, London 2011, pp. 188–201.

(1) Dillian Gordon, Duccio di Buoninsegna, ‘The Virgin and Child with Saint Dominic and Saint Aurea, and Patriarchs and Prophets. In David Bomford, Jill Dunkerton, Dillian Gordon, Ashok Roy, Jo Kirby, National Gallery Catalogues, The Italian Paintings before 1400′, London 2011, pp. 188–201.

(2) K. Christiansen, Duccio and the Origins of western painting, The Metropolitan Museum of Art Bulletin, Summer 2008, New York

(3) J. H. Stubblebine: Duccio di Buoninsegna and his School, 2 vols. (Princeton, 1979).