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In designing ink jet printing devices, the greatest challenge is not in the design of the mechanism nor control aspects of the head. Surprising to many, it is the difficult task associated with the formulation of inks, toners and papers which will give you a suitable image. This image must possess good chromatic and archival characteristics. In the past, inks were the cause of much criticism associated with the bad reputation of ink jet printers; and rightly so. The inks used in ink jet printing were expected to perform many difficult tasks. They were subjected to evaporation and stability tests at high temperatures. They were expected to retain their physical parameters of viscosity, surface tension and pH for months in an oven at 40-60° C. Yet, when they were emitted onto a piece of paper at ambient conditions, they were expected to dry within 3 seconds. Chemists who were formulating inks based on criteria established by mechanical and electrical engineers were at a disadvantage. Inks were not considered a major component to other groups in the development program. Yet inherently, the ink was causing the majority of system failures due to head clogging, component breakdown, etc. The ink chemist was at a distinct disadvantage to begin with. A major cause for orifice clogging was the precipitation of salts out of the dye. Dyes may contain as much as 20 percent salt. A dye with less than 1 percent salt content was not available a few years ago. Today, however, dye manufacturers see the increase of requests for purer dyes and are making them available for a premium. There were not any specialty papers available for ink jet applications. Inks would either sit on the surface of the paper and not dry, or they would cause feathering or bleeding problems. Today there is a variety of papers available for ink jet systems.
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