In the urban landscape paintings, stripped of the human figure, a journey from the figurative to the abstract and back is encountered. The early artworks are an echo of the encounter with the Israeli landscape in his neighborhood of Yad Eliyahu. Despite the seemingly refreshing palette of colors, influenced by the harsh local sunlight, the painting emits a nagging sense of a city estranged from one who does not yet feel at home.
In Paris at the end of the 1950s, his paintings are characterized by their cubist rendering. Others are anchored in figurative painting, yet they stand out as being disengaged from naturalism and transitioning to the depiction of imaginary landscapes.
Bak’s move from Paris to Rome saw a pivotal turning point in his art. For the first, he felt mature enough to return to his childhood provinces. His artistic language undergoes a process of maturation brought about by his direct encounter with European abstract expressionism. This encounter opened for the artist a window onto anti-geometric, anti-naturalist artistic expression, dominated by spontaneity and the burrowing into subconscious recesses. The emotional depth of the paintings is expressed in his brushstrokes, his storm of emotions revealed in the tremulous texture.
Bak’s adherence to abstract expression is never unequivocal, thus many canvases are inhabited with images only partially abstract, the imaginary space resting on an illusory perspective. In 1964, at the Venice Biennale, Bak was exposed to the American "Pop Art", which legitimized his desire – to use and embed figurative language in his artworks, while simultaneously remaining a contemporary artist.