Whether it’s a billboard, bus or banner, we’re all exposed to examples of large-format printing on a daily basis. It’s used to produce large graphics for marketing, branding, and advertising purposes and can take many forms. Products are generally for the point-of-sale (POS) sector and include banners, posters, wallpaper, murals, vehicle branding, signage and other large requirements.
But what exactly is large-format printing?
Quite simply, large-format printing is a general term for the digital printing of a design onto a large substrate. Prints are much larger than a common commercial printer can handle, so it requires the use of specialist equipment. Wide-format is a type of large format printing and wide-format printers are generally accepted to be any computer-controlled printing machine that support a print width of 18” to 100”.
Printers with that can handle widths of more than 100″ are considered super-wide or grand format.
Only emerging at the end of the last century, wide-format printing is a relatively new development in the printing industry. The first wide-format digital printers were electrostatic technology, which was pioneered by Xerox. Inkjet technology was later introduced jointly by HP and Canon. Wide-format printing has evolved rapidly in the last 15 years – and with this technology evolution, the range of inks, substrates and printers have also expanded dramatically.
Wide-format printers usually use inkjet or toner-based technology to produce the printed image; and are far more economical than other print methods (such as screen printing) for most short-run print projects.
Wide-format printing can be roll-fed or flatbed. In roll-fed, the roll is fed incrementally through the printer. In flatbed, the substrate is loaded onto a table which then moves under a print head array.
UV solvent inks are then printed directly onto the substrate through inkjets. Solvent-based inks adhere to a wide range of substrates and have exceptionally good weather, UV and abrasion resistance.
Wide-format printers are categorised by the type of ink transfer process they employ:
Thermal or Piezo inkjet printers use aqueous (or water-based) inks. The term ‘water-based’ is a generally-accepted misnomer as the pigment is held in a non-reactive carrier solution that could be water or another substitute liquid.
Aqueous ink can be dye or pigment. Dye ink is a high colour, low UV-resistant variety that offers the widest colour gamut. Pigment ink is generally duller in colour and requires more ink to achieve deep colour, but better withstands fading from UV rays.
Aqueous technology requires that all materials be properly coated to accept and hold the ink and printed products must be laminated to protect them if they are to be used outdoors. Substrates include canvas, banner material, metabolised plastic and cloth.
Solvent is used to describe any ink that is not water-based and these inks use petroleum or a petroleum by-product such as an acetone like carrier liquid. “Eco-Solvent” inks usually contain glycol esters or glycol ether esters and are slower drying.
The solvents soften the base material and allow the ink pigments to mechanically latch on to the chemically etched surface. This means that solvent can be used to print directly on uncoated vinyl and other media as well as ridged substrates such as painted or coated metal, foam board and PVC.
Solvent ink is more durable than aqueous inks and prints are waterproof. The downside is that solvent inks give off a strong odour or fumes when drying, as the carrier fluid dissipates through applied heat from the printer’s platen.
Inks are diffused into the special print media to produce continuous-tone prints of photographic quality.
Piezo inkjet printers uses inks that are UV-curable (dry when cured with UV light). The resulting prints are waterproof, embossed and vibrant. Although any media can be used with this technology, polymer media is best. Ceramic, glass, metal and wood can be printed with this technology.