Sennhauser was an abstract painter whose style ranged from realism to non-objective in the early 1940s. In 1943 he worked at the Solomon R. Guggenheim Foundation where he started working purely in abstraction.

Sennhauser’s composition, Improvisation, 1944, exhibits geometric shapes and lines. The viewer’s attention is drawn to the irregular heptagon (7 sided shape) in the left central portion of the canvas. Four rectangle-like shapes are placed in the heptagon as well as two zigzag lines. Crosshatching is visible behind the heptagon. The lower portion of the canvas consists of four-sided shapes: squares, rectangles, trapezoids. These shapes are intermingled with rectangular blocks of red, blue, green, and white. The ‘haphazard’ nature of the composition is reminiscent of the early abstract artists’ ideas of ‘chance’ incorporated into their paintings. The title, Improvisation, gives further evidence of this idea and the un-planned, spontaneous creations.