Max Ernst is the surrealist artist strongly associated with the technique of grattage.
The word grattage means “scraping” or “scratching.” In the process, an artist applies wet paint over a textured object and then scrapes the surface with a blade or another tool. The exposed layers create accidental patterns that can suggest rocks, plants, animals, or other forms.
Ernst developed grattage from his experiments with frottage, a rubbing technique he rediscovered in 1925. In 1927, he transferred the idea from paper to oil painting, using scraping to encourage images to emerge from chance rather than from deliberate planning. This fit Surrealism’s interest in automatism and the unconscious.
Joan Miró also used grattage, so he is a plausible distractor, but Ernst is the canonical answer because he is credited with creating and systematizing the process. Grattage is related to frottage, yet the former removes paint while the latter transfers texture through rubbing.