During the working process they usually first focused on content and composition. Every color transmits certain emotions, which in turn have an effect on the message. To them, simplicity and abstraction help transmitting this message in a very direct yet open way, while color is something very subjective. Everyone has different associations seeing for example a green square. One is reminded of the coat of his grandma, the other of the peas he was forced to eat as a kid. It can be easy or very hard to work with colors. They were more interested in observing and finding out how the different content can be stripped down to its most important information through a specific composition of letters, forms, shapes and contrasts. How far can we go in abstraction? Using black and white or a greyscale can help you making very precise decisions in those contrasts.
