In the first decade of the artist’s career, the 1950s, the concept of his black monochromes takes shape. Verheyen defines these works as Schwarz darstellen or ‘depicting black’, a reference to Paul Klee. His Espace Noir works are black vibrant and foggy atmospheres with no beginning and no end, and are mostly painted with oil on burlap. In the second part of the 1950s, Verheyen made his first white monochromes (Espace Découpé, Monochromie [458]) on wood as well as on panel. The artist experiments with  collage and mixed media such as silver paint, smoke, glue, and nylon.