Printer Faults - Irregular Vertical Stripe.

Vertical repetitive defects are almost always caused by a problem with one of the print process rollers. The OPC drum and fuser are the most likely causes because they wear out and are exposed to accidents. The pattern suggested here tends to be characteristic of a fuser.

An elongated vertically oriented repeating stripe with random patterning in it is likely to be a degenerating fuser roller or foil. The immediate cause is likely to be that some of the non-stick material has flaked away from its roller or foil.

Missing non-stick leads to random collections of toner building up and breaking away and grey-black patches printing down the page at a pitch determined by the fuser roller.

Fuser non-stick coatings are typically polytetrafluoroethylene (PTFE, better known by the DuPont tradename Teflon). The substance has strong carbon-flourine bonds and is very non-reactive to other things. Molecules of PTFE are long and weakly cross linked; if the material tears away from the surface it is bonded to it tends to do so as an irregular string.

Bonding PTFE to a metal roller needs special techniques such as sodium napthalene (tetra-etch)or plasma etching. Nevertheless any mechanical damage tends to rip the non-stick away from the roller. Never poke at the non-stick material with anything sharp or abrasive as the least mechanical damage will quickly result in a patch of the material coming away.

This failure is often seen first on one or both margins where it is called edge-wear. The fuser puts some pressure on media as they pass through and this means the rollers distort a bit in the positions where page edges commonly pass. Depending on the design of fuser it is also quite characteristic to have a stripe mid-page where the thermistor or thermal cutout rubs on the roller or foil.

Non-stick properties don't seem to last forever. Ultimately the properties decline and toner starts to build up on the surface.

Using the wrong grade of toner might be a problem. Modern toners often incorporate a styrene component that make up the bulk of the carrier for the pigment and a wax that melts more easily and acts as a releasing component on the surface of the fuser. Other toners might work but be more inclined to build up on the fuser roller. There is an argument here for using manufacturers original toners; if half-price toners half the life of the fuser there might still be an argument for using them - but a less conclusive one. (Cartridge yield, defective cartridges and support costs are other arguments).

Fusers are fairly complicated assemblies. For some printers a replacement roller or film - foil might be available. Replacing these parts is time-consuming however, so they are no longer widely available. The normal cure is a new fuser.