With his typography, Gerstner follows the Swiss tradition of clear and minimalist design, and develops a new type of text-image relationship in the design of posters and brochures. In the 1970s, he leaves the agency to concentrate on his artistic work. Gerstner becomes successful as an artist and consultant. He dedicates his art to the search for a pictorial system and the research of colour effects. He is one of the important representatives of Concrete Art in Switzerland.