 Klein persuaded Clert to keep one of his paintings, a small orange monochrome, as a trial run.She displayed the monochrome in the corner of the one-room gallery.The painting proved to be successful, and upon Klein's return, Clert invited him to exhibit a few of his monochromes in the gallery's first major exhibition in April 1957, called "Micro-Salon d'Avril" ("Micro-Salon of April").