Each band has variations within it. The painting is divided into sections by the bands and these further serve to group the space into bigger blocks.
Klee's paintings were often Surreal. He aimed to express dreamlike ideas in a real way. The Separation in the Evening makes his ideas a firm reality. It gives onlookers an enigmatic puzzle to ponder. His philosophical ideas are not completely clear in this or at least, not as clear as they are in a painting like Refuge. However, he does bring across the idea of separation strongly.
The top of the painting is formed using a thin red band and a very dark band. Below that, there is soothing collection of blue bands which go from dark blue to a lighter blue. The artists then uses a very light shade to transition to bright yellow bands. In a way, this piece might remind viewers of an exercise in colour theory.
Watercolours were used to paint this piece, which was completed in 1922. Klee's experience as a draughtsman can be clearly seen in this piece. In fact, as an Abstract painter, he seems to enjoy playing with the lines. The arrows point towards each other leading viewers to the conclusion that there may be a meeting at some point or some sort of convergence of ideas.
If this meeting never happens, it will not be surprising. The colours are as far apart as night and day. If the colours chosen are used to represent two distinct personalities, it is unlikely that they would converge harmoniously without a great deal of work on both sides. The gap between the two extremes is immense. Even though Klee has used intermediate shades between them to help bridge that gap, it is obvious that they are some distance apart.
Watercolour is used to successfully transition from one band of colour to another. This medium makes it easier to do the delicate washes necessary to make the technique effective. Klee's somewhat uninhibited expression is used to bring focus to the separation explored in this piece.