A process for the heat treatment of a coating deposited on at least one portion of a first face of a substrate including a first face and a second face opposite the first face, wherein the coating is treated by a laser radiation focused on the coating in the form of a laser line extending along a first direction, the heat treatment being such that, in a second direction transverse to the first direction, a relative displacement movement is created between the substrate and the laser line, wherein the second face is heated locally at a temperature of at least 30° C. in an additional heating zone extending facing the laser line over a length of at least 10 cm along the second direction, with the aid of at least one additional heater positioned on the side opposite the laser line with respect to the substrate.