Ink-jet printing

Jet printing may be defined as a process by which the desired pattern with its individual colours is built up by projecting tiny drops of 'ink' (special dye liquors) of different colours, in predetermined micro-arrays (pixels), onto the substrate surface. In all true jet printing systems the ink is projected onto the surface as a controlled series of drops. Usually a set of inks is used consisting of at least three or four primary colours, namely cyan (turquoise), magenta, yellow and optionally black, the so-called CMYK inks. As most ink-jet printers were originally designed for paper printing, the terms encountered in, for example, technical specifications are more related to those used in the reprographics industry than to those that a textile printer would normally employ. Thus reference is usually made to inks rather than dye solutions, pigment dispersions or print pastes. Similarly print resolution is usually defined as dots per inch (dpi) or lines per inch (lpi).

In the field of textiles ink-jet printing is fundamentally different from that of all other techniques, not only because of the non-contact mechanics of the print head but also in the means by which the individual colours of a design are produced. A great deal of computation is necessary to produce each of the millions of pixels in a design and this continues for as long as the machine is printing the fabric. In the past printing machines were adjusted entirely by mechanical methods using the operator's experience and judgement, and although modern impact printing machines may be fitted with more refined feedback devices, these are considerably less sophisticated when compared with the electronic control of jet printers.