A method for forming a film of particles on a carrier liquid present in a receptacle, for depositing this film onto a substrate, the method including: making a film blank between a barrier and a head including a tilted ramp, the blank being obtained by dispensing particles via the tilted ramp and carried out until the particles floating on the carrier liquid occupy a space between the barrier and an upstream front of particles located on the tilted ramp; and elongating the film by continuing dispensing the particles, and moving the head to move away from the barrier, the film elongation being performed to hold a front of particles on the ramp.