Juul (Julius Hermann) Neumann joined Berend Hendriks for a weekly drawing class with Ger Gerrits after his graduating in 1936. Here he also came into contact with Harry van Kruiningen. During the war, Neumann and Hendriks shared a workshop in Amsterdam, where he produced his first paintings. In 1945, Neumanns language of forms hovered between figurative and abstract under the influence of cubism (Braque). Neumann took, despite his regular job, as much as he could part in the exhibitions of Vrij Beelden, Creatie and later on the Liga Vrij Beelden with abstract oils.
In 1946 he joined De Onafhankelijken with Hans Ittmann. From 1949 onwards he called his works compositions and started numbering them. Typical for both his paintings and his wood carvings from these years are the limited use of only the primary colours combined with black, or grey and white, and developing geometry in his shapes. The earliest compositions are made of a few shapes and lines.
After 1954 Neumann took on a new way of composing geometric and half-geometric organic shapes. He continued in this fashion on exhibitions between 1955 and 1960 of the Liga Nieuw Beelden, for which he was a member of the board as the treasurer until 1969.
In the mid-sixties, he temporarily switched to a more liberated abstract style in which landscapes and cityscapes where the starting point of the abstraction. After that, he returned to a strict geometric language of forms.