Along with the development of faster wide format inkjet printers and more advanced print heads, ink manufacturers have introduced an array of ink formulations. There seems to be a different ink for each wide format application such as photo, outdoor signage, vehicle wraps, fine art reproduction, and rigid POP. This article may serve as a brief primer on wide format inkjet inks.
The most common wide format digital printing devices are based on aqueous, or water-based inkjet ink. Aqueous inks produce beautiful results but require the use of coated papers and films. The first generation of aqueous inks for wide format were dye-based. These water-based inks used easy-to-mix dyes as colorants to provide exceptionally wide color range. Since a lot of wide format digital printing is intended for outdoor applications, ink chemists developed pigment-based inks that are inherently more fade-resistant than the dyes used in the first generation of inks.
Solvent-based inks are used to produce outdoor durable graphics on uncoated substrates like vinyl, mesh, and canvas. In the inkjet world, the term solvent is used to describe any ink that is not water-based. It is the solvent ink's ability to print directly onto banner vinyls and other plastics that makes them so valuable. Epson and Mimaki are two vendors who manufacture solvent inks, along with their solvent wide format printers.
Mild-solvent inks (sometimes referred to as eco-solvent inks) were introduced in 2001 to appeal to smaller sign shops that wanted affordable inkjet printing systems that would enable them to output graphics onto lower-cost materials without having to install the heavier-duty ventilation systems required by more robust solvent inkjet printers such as the VUTEk and NUR grand format devices. The inks and printers in the eco-solvent segment have improved so much that InfoTrends believes some of the eco-solvent printers provide image quality that is comparable to aqueous inkjet. These printers have grown in popularity because they are relatively low cost (typically below $40,000) and their running costs are lower than those of aqueous inkjet. Mimaki, Mutoh, and Roland have all introduced eco-solvent inks. Another version of eco-solvent is mild-solvent or safe solvent. HP, Océ, Xerox, and Epson all have versions of these other types of eco-solvent printers.
In late 2006, EFI/VUTEk introduced its bio-solvent ink, named BioVu. EFI-VUTEk suggests that BioVu is the next generation of environmentally-friendly inks made with a renewable resource, corn, and that the inks provide all the benefits of traditional solvent inks in terms of their durability, ability to bond to uncoated substrates, and so forth. Mutoh has also launched a product called MUBIO, again based on renewable resources. There are a number of other companies such as Bordeaux and Fillink Technologies, that are developing greener alternatives to robust solvent inkjet inks. There is some way to go before these inks should be considered "green" products or part of a green printing process, however.
At a preview event for the 2008 Drupa tradeshow, HP announced Latex Printing Technologies. The new water-based HP Latex Inks are designed to offer an environmentally responsible large-format printing alternative for a wide variety of outdoor and indoor applications and produce odorless prints (although some substrates may have inherent odor, HP points out). The latex inks will work with new printers that were announced at Drupa; printers using the new inks will use internal heaters to dry and cure the latex polymer film. HP suggests that latex inks will work with a broad range of HP and non-HP large-format media, and will provide display permanence up to three years unlaminated.
UV-curable inks were first introduced into the screen-printing world about 20 years ago and debuted on flatbed digital inkjet printers in 2001. It was hoped that UV-curable inks could provide a more environmentally friendly, but equally versatile alternative to the most robust solvent-based inks used in large-format graphics. One of the most notable advantages is the instant dry feature that leaves the printed graphic completely cured.
There is a lot to know about inkjet inks for wide format printing. The development of newer and more capable inkjet inks will continue, providing equipment and supplies dealers an exciting opportunity, because end users count on dealer advice for which systems they should buy and which are best for their customer base.