<P> Toner is a powder mixture used in laser printers and photocopiers to form the printed text and images on the paper, in general through a toner cartridge . Mostly granulated plastic, early mixtures only added carbon powder and iron oxide, however mixtures have since been developed containing polypropylene, fumed silica, and various minerals for triboelectrification . Toner using plant - derived plastic also exists as an alternative to petroleum plastic . Toner particles are melted by the heat of the fuser, and are thus bonded to the paper . </P> <P> In earlier photocopiers, this low - cost carbon toner was poured by the user from a bottle into a reservoir in the machine . Later copiers, and laser printers from the first 1984 Hewlett - Packard LaserJet, feed directly from a sealed toner cartridge . </P>

What is needed for the complete application of toner to paper