From the beginning, Żak expressed his artistic temperament through a sophisticated application of line, referring in his sanguine portraits to works by Leonardo, Botticelli, Holbein and Dürer. In the early stage of his career, he approached the style of the Nabis, through the manipulation of flat areas, enclosed within distinct contours and faded, slightly matte colors. For a brief period, he succumbed – like so many of his Parisian colleagues – to the exoticism and folk atmosphere of Brittany. He also borrowed certain motifs from Chinese porcelain and Persian miniatures. He painted views of Parisian back streets and boulevards on the Seine and, sporadically, took up New Testament themes.