Toner

Toner is a powder mixture used in laser printers and photocopiers to form the text and images on paper, in general through a toner cartridge. Mostly granulated plastic, early mixtures added only carbon powder and iron oxide; now there are mixtures that contain polypropylene, fumed silica, and various minerals for triboelectrification.^[1] Toner using plant-derived plastic also exists as an alternative to petroleum plastic.^[2] Toner particles are melted by the heat of the fuser, and are thus bonded to the paper.

In earlier photocopiers, this low-cost carbon toner was poured by the user from a bottle into a reservoir in the machine^{[citation needed]}. Later copiers, and laser printers from the first 1984 Hewlett-Packard LaserJet,^[3] feed directly from a sealed toner cartridge.

Laser toner cartridges for use in color copiers and printers come in sets of cyan, magenta, yellow and black (CMYK), allowing a very large color gamut to be generated by mixing.