Agent for magnetographic printers and use of such an agent

A method of printing using an agent, said agent including a plurality (k) of elementary magnetic layers disposed on a soft magnetic substrate and having relatively hard hysteresis cycles with a defined writing threshold and saturation magnetization, wherein at least one of a coercivity and a thickness of said layer varies as a function of a depth of the layer on said soft magnetic substrate, the method comprising the steps of:

• providing a plurality of writing heads;
• printing n.sup.2. k grey shades on a sheet of paper, wherein n is a number of dots used to define a pixel size and wherein said soft magnetic substrate is coated with k layers, enabling grey levels to be defined as a function of different thicknesses of the layers or of different coercivity of the layers;
• applying a different writing threshold to each writing head of said plurality of writing heads, thereby obtaining k grey levels per elementary dot defined by different masses of toner retained per unit of surface area;
• and
• printing, with the plurality of heads having n.times.n points.