Blase’s long-term clients were Staatstheater Kassel (Kassel State Theater) and Atlas Films. Karl Oskar Blase produced countless posters for these two organisations. It’s not surprising considering Blase designed posters for the Staatstheater for twelve years between 1966 and 1978.
The designer is unstated on these postcards, which were designed during the mid to late 1970s, but these playful illustrations alongside what looks to be Frankfurter Bold definitely fit the criteria of friendliness and efficiency
He designed stamps from around 1955 and in the book Karl Oskar Blase, Briefmarken-Design, Verlag für Philatelistische Literatur, 1981, he was described as one of the most influential stamp designers in Germany.
