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A color toner bottle

Toner is a powder used in laser printers and photocopiers to form the text and images on the printed paper. In its early form it was simply carbon powder. Then, to improve the quality of the printout the carbon was blended with a polymer. Toner particles are melted by the heat of the fuser, causing them to bind to the paper. The specific polymer used varies by manufacturer but can be a Styrene Acrylate Copolymer or a Polyester Resin. Toner formulations vary from manufacturer to manufacturer and even from machine to machine. Typically formulation, granule size and melt point vary the most.

The original particle size of toner averaged 14-16 micrometres (microns)[1] or greater. To improve image resolution particle size was reduced, eventually reaching about 8-10 microns for 600 dots per inch resolution. Further reductions in particle size producing further improvements in resolution are being developed through the application of new technologies such as Emulsion-Aggregation. [2] Toner manufacturers maintain a quality control standard for particle size distribution in order to produce a powder suitable for use in their printers.

Toner has traditionally been made by compounding the ingredients and creating a slab which was broken or pelletized and then turned into a fine powder with a controlled particle size range by air jet milling. This process resulted in toner granules that, if viewed under a microscope, showed varying sizes and jagged shapes. To get a finer print, some companies are using a chemical process to grow toner particles. This results in more uniform size and shapes of toner particles. The resulting smaller uniform shapes permit more accurate color reproduction and more efficient toner use.

In earlier machines toner was poured by the user from a bottle into a reservoir in the machine. Modern machines feed directly from a cartridge. Empty cartridges are often refilled by third party vendors.

As a fine powder, toner can remain suspended in the air for some period, and is considered to have health effects comparable to inert dust. It can be an irritant to people with respiratory conditions such as asthma or bronchitis. Following studies on bacteria in the 1970s that raised concerns about health effects resulting from pyrol, a contaminant created during manufacture of the carbon black used in black toner, manufacturing processes were changed to eliminate pyrol from the finished product.

Toner can be washed off skin or garments with cold water. Hot or warm water will soften the toner, causing it to fuse to the material it is on. Toner fused to skin will wear off in time, or can be partially removed using abrasive hand cleaners. Toner fused to clothing cannot usually be removed.

Look up toner in Wiktionary, the free dictionary.

• Hewlett-Packard, Material Safety Data Sheet: HP Laserjet Print Cartridge C4127A/X, online, URL Date 25 August 2004
• Hewlett-Packard, Material Safety Data Sheet: HP Laserjet Print Cartridge Q1338A, online, URL Date 25 August 2004
• Malvern InstrumentsToner Particles - Monitoring Particle Size Distribution and Particle Shape

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