As its name suggests, Signal Art’s key characteristic was powerfully bright, eye-catching colours. This central feature had a theoretical basis and was linked to psychological perception theories, which explain sensations.
In addition to its strong palate, Signal Art was characterised by forms with precise and sharp contours, which were often reduced geometric figures. Although the style can thus be linked to American Hard Edge painting, the main representatives of the style -Winfred Gaul (1928-2003) and Georg Karl Pfahler (1926-2002) – were German. The most important American Signal artist was Robert Indiana (born 1928). Signal Art’s debt to Hard Edge is most visible in Georg Karl Pfahler’s paintings and their colour fields. But Pfahler’s work was also characterised by a very expressive personal imprint, the inclusion of rounded edges, which were interlinked, so that they appeared to interact. Pfahler’s work was mostly defined by the use of powerful colours, and their signal-like luminosity created a striking effect.