Guernica was painted using a matte house paint specially formulated at Picasso's request to have the least possible gloss. American artist John Ferren assisted him in preparing the monumental canvas,John Ferren biography, guggenheim.org. Retrieved 17 November 2020. and photographer Dora Maar, who had been working with Picasso since mid-1936 photographing his studio and teaching him the technique of cameraless photography,Fluegel (1980), p. 308. documented its creation. Apart from their documentary and publicity value, Maar's photographs "helped Picasso to eschew color and give the work the black-and-white immediacy of a photograph", according to art historian John Richardson.
