The basic problem with inkjet inks is the conflicting requirement for a colouring agent that will stay on the surface and rapid dispersement of the carrier.

Small inkjet printers as being used in offices or at home, all use aqueous inks based on a mixture of water, glycol and some dyes or pigments. These inks are inexpensive to manufacture, but are difficult to control on the surface of media and therefore require often specially coated media. Aqueous inks are mainly being used in printers with disposable, so-called thermal, inkjet heads, as these heads require water in order to perform.

In professional wide format printers, a much wider range of inks are being used. Most of these inks require piezo inkjet heads:

In solvent inks, VOCs are the main ingredient. Advantage of these inks is that they are very inexpensive and enable printing on uncoated vinyl substrates, which are used a lot in advertising for billboards and fleet graphics.

UV-curable inks consist mainly of acrylic monomers with an initiator package. After printing, the ink has to be cured by a high dose of UV-light. Advantage of UV-curable inks is that they dry instantly, can print on a wide range of uncoated substrates and make a very robust image. A disadvantage is that they are more expensive and require expensive curing modules in the printer.

Dye sublimation inks contain special sublimation dyes and are used to print directly or indirectly on fabrics that consist of a high percentage of polyester fibres. In a heating step the dyes sublimate into the fibers and create an image with strong color and good durability.
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Inkjet head design

Two main design philosophies operate in inkjet head design. Each has strengths and weaknesses.

The fixed-head philosophy provides an inbuilt print head (often referred to as a 'Gaither Head') that is designed to last for the whole life of the printer. The idea is that because the head need not be replaced every time the ink runs out, consumable costs are typically lower and the head itself can be more precise than a cheap disposable one. On the other hand, if the head is damaged, it is usually necessary to replace the entire printer. Epson have traditionally used fixed print heads featuring micropiezo technology. These print heads are available in consumer products and are traditionally more accurate in dot placement than comparable thermal printers.

Other fixed head designs are more likely to be found on industrial high-end printers and large format plotters.

Fixed-head designs normally use piezo inkjet heads. Because development of these heads requires a large investment in research and development, there are only a few companies offering them: Trident, Xaar, Spectra (Dimatix), Hitachi / Ricoh, HP Scitex, Brother, Konica Minolta, Seiko Epson, and ToshibaTec (a licensee of Xaar).

The disposable head philosophy uses a print head which is part of the replaceable ink cartridge. Every time the printer runs out of ink, the entire cartridge is replaced with a new one. This adds to the cost of consumables and makes it more difficult to manufacture a high-precision head within reasonable cost limits, but also means that a damaged print head is only a minor problem: the user can simply buy a new cartridge. Hewlett-Packard has traditionally favoured the disposable print head, as did Canon in its early models.

An intermediate method does exist: a disposable ink tank connected to a disposable head, which is replaced infrequently (perhaps every tenth ink tank or so). Most high-volume Hewlett-Packard inkjet printers use this setup, with the disposable print heads used on lower volume models.

Canon now uses (in most models) replaceable print heads which are designed to last the life of the printer, but can be replaced by the user if they should become clogged. For models with "Think Tank" technology, the ink tanks are separate for each ink color. Hewlett-Packard is now also experimenting with fixed print heads on many of their upcoming low-volume models.