Editing Laser printing (section)

===Developing===
As the drums rotate, [[toner (printing)|toner]] is continuously applied in a 15-[[micron]]-thick layer to the ''developer roll''. The surface of the photoreceptor with the latent image is exposed to the toner-covered developer roll.

Toner consists of fine particles of dry plastic powder mixed with [[carbon black]] or coloring agents. The toner particles are given a negative charge inside the [[toner cartridge]], and as they emerge onto the developer drum they are electrostatically attracted to the photoreceptor's latent image (the areas on the surface of the drum which had been struck by the laser). Because negative charges repel each other, the negatively charged toner particles will not adhere to the drum where the negative charge (imparted previously by the charge roller) remains.