Method of heating a blank (2) of plastic material for the manufacture of a hollow body by forming from the blank (2), which comprises the operations consisting of: inserting the blank (2) into an oven (7) provided with sources (9) of monochromatic or pseudo-monochromatic electromagnetic radiation emitting in the infrared range; exposing the blank (2) to the radiation from the sources (9), adjusted to a predetermined emission power for a predetermined exposure time; measuring a temperature on an outer wall (16) of the blank (2); Characterized in that it comprises an operation consisting of: adjusting the exposure time and/or the emission power so that said temperature at an exit from the oven (2) [sic: (7)], does not fall between Tg and 1.8·Tg, where Tg is the glass transition temperature of the material.