Boudin’s sky pastels are almost like ephemeral pictorial photographs. On some of them, indeed, he notes precise details, date, hour, orientation and meteorological indications. He plans his skies just as real-life ones. From time to time he uses a very discreet indication of land at the bottom of his work to “situate” his sky. The painter, “king of the skies” as Corot said, uses only a limited palette often integrating the colour of the cardboard, the principle of reserve.