Toner cracking

When the media is folded and the crease aligns with a line of text, it is possible with certain types of media for the text to break along the line, giving the appearance of a white line through the text. Media that does not meet the smoothness (100 to 250 Sheffield, 100 to 500 Bendtsen) or wax pick (>11 Dennison) is likely to exhibit this effect more than other media.

Toner in the HP LaserJet printers is composed of minute particles of pigmented plastic material (styrene) and iron oxide. When the toner is subjected to the fusing temperature, these individual, iron-impregnated plastic particles become part of a larger plastic image on the page. When the printed page is subsequently folded, the plastic image must also give in some fashion to accommodate the fold. If the print image has been well-set into the paper, the resulting break in the plastic will not be apparent. However, if the toner is unable to adequately penetrate the paper fibers, or if in the process of folding the paper the paper fibers behind the toner break away from the page itself, the result will be a “white line” through the image. There are several ways to minimize this effect:

•Ensure that the media being used meets all of the specifications provided in the HP LaserJet Printer Family Print Media Guide, in particular the smoothness and wax pick.

•A lighter density setting will ensure that the toner image will be composed of less plastic material, thus minimizing the resulting effect of trying to fold the toner image.

•For the reasons listed earlier, a more narrow, character-stroke width might also help.

•Magnetic Ink Character Recognition (MICR) paper might fix toner cracking problems (see also the HP MICR User’s Guide).

In photocopier (laser) printing, using media that has a laid finish often causes problems. The surface roughness of the media is often responsible for the problems.

Media that is stiffer than photocopier paper also causes problems. Stiff media does not fold well. Problems increase when stiff media is folded and a toner image is applied to the media’s surface.

168 Chapter 6 – Toner cartridge information

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