<P> The photographer Dora Maar--who had worked with Picasso since mid-1936, photographing his studio and teaching him the technique of cameraless photography--documented the stages Guernica went through on its way to completion . 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 John Richardson . The work was painted using a matte house paint specially formulated at Picasso's request to have the least possible gloss, and the American artist John Ferren assisted him in stretching the monumental canvas . Previously, Picasso had rarely allowed strangers into his studio to watch him work, but he admitted influential visitors to his studio to observe the progress of the painting, believing that the publicity to be gained would help the antifascist cause . </P> <P> As he worked on the mural, Picasso said: "The Spanish struggle is the fight of reaction against the people, against freedom . My whole life as an artist has been nothing more than a continuous struggle against reaction and the death of art . How could anybody think for a moment that I could be in agreement with reaction and death?...In the panel on which I am working, which I shall call Guernica, and in all my recent works of art, I clearly express my abhorrence of the military caste which has sunk Spain in an ocean of pain and death ." </P> <P> After 35 days of work, he finished the painting on 4 June 1937 . </P> <Table> <Tr> <Td> </Td> <Td> This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (April 2017) (Learn how and when to remove this template message) </Td> </Tr> </Table>

How long did it take picasso to paint guernica