Landscapes, cityscapes, ports, rivers, docks and figures are the main subjects of Jan Sirks’s paintings.
In the early 1900s we see the first oil paintings. Sirks chose the immediate environment of Rotterdam with its farms, ditches and paddocks. During World War 1 Sirks joins the Theosophical Society and he paints the first busy urban landscapes with isolated figures. The landscape paintings of this time show a pre-occupation with horizontal and vertical lines. In the early 1920s Sirks returns to working inside the actual farmyard, his palette has strong tonal contrast and he depicts detail rather than his earlier vistas. His palette becomes increasingly more symbolic with his use of orange and green.
In the 20s Sirks moves increasingly closer to his subject matter and we see a bold palette in his summer skies and his autumnal colours are vibrant. Sirks treatment of the landscape changes as he matures as his vistas become increasingly larger.