The CARR Group, as an established supplier to the wide-format printing industry, stocks media for all the major ink types. This article seeks to give a brief overview of the main ink technologies that are used in the wide-format printing arena.
Ink Types for Digital Inkjet Printing
There is a variety of inks available in the world of digital inkjet printing. All inks share the same main components: a colourant (pigment or dye) and a carrier liquid. The defining difference lies in how the colour adheres to the substrate.
It can be confusing knowing which ink is the best choice for a particular application, but in reality, there is a lot of crossover between ink types and suitable substrates.
The below is designed to give a brief overview of the main ink technologies in the wide-format digital inkjet printing space. Inks continue to develop and improve and new hybrid inks come to the market regularly (such as solvent-UV or gel ink).
… ink refers to the oil-based carrier solution that holds the pigment. This ink type has been around for a long time. The solvent dissolves into the top surface of the substrate so that the pigment colourants are etched into it after the solvent evaporates. It is highly durable, fade and scratch resistant plus waterproof.
However, the solvent contains VOCs (volatile organic compounds) which have a strong smell during drying and also afterwards which makes printed items not suitable for indoor applications. The vapour is hazardous to printer operators, so ventilation and extraction are required. The solvent needs to outgas after printing which means that finishing (especially laminating) needs to wait for a defined period, often the following day.
Solvent ink can print onto many different and also uncoated substrates such as banners and vinyls. Outdoor signage and billboards, banners, mesh, vehicle wraps and truck curtain sides are among the main applications.
Eco (Light) Solvent
… inks were developed as an alternative to the strong solvent inks. They contain fewer hazardous compounds and there is no significant smell during or after printing. Eco (or low) solvent printers can be used in office environments without ventilation. Same as with strong solvent ink, the solvent is evaporated by heat. Following the printing, it is required to let the ink outgas for up to 24 hours to make sure all solvent is gone before finishing the media.
The outdoor longevity is less than can be achieved with strong solvent inks.
It is used for indoor and outdoor sign and display, billboards, point of sale, self-adhesive vinyl, mesh, vehicle wraps to name just a few.
… inks are water-based with resins and additives that are heat-cured to bind the pigment to the substrate. There are no VOCs and it does not smell, so no ventilation/extraction is necessary. The media can be finished straight after printing. Latex ink has similar benefits of brightness and durability as solvent inks.
It is used for a wide variety of media/applications such as coated paper, posters, photographs, indoor display, point of sale, banner & billboards, self-adhesive vinyl and wallpaper. It is also increasingly used on soft signage and home textiles.
… inks remain liquid until exposed to UV light which causes the ink to cure by polymerisation, causing it to harden into a dry film that traps the pigment. As such, the carrier liquid does not evaporate like with solvent and latex inks. The ink does not etch itself into the media but “sits” on the surface. It dries almost instantly.
UV curable inks are ideal for printing directly onto rigid substrates such as PVC or PP boards, glass, wood, metal and POP but are also widely used on roll to roll media, such as mesh, banners, vinyl and increasingly soft signage.
… inks are absorbed into synthetic textiles or surfaces on solid objects. The dye is suspended in water as the main carrier. Dye sublimation ink can be either printed on a special transfer paper and then transferred by heat and pressure onto the substrate, or printed directly to the textiles and then heat set. The heat causes the polyester fibres to open, and the pressure forces the ink to enter the fibres. When the material cools the fibres “close” and encapsulate the dye, which makes for very high colour fastness and high UV resistance.
Applications: Soft signage including trade show graphics, retail and POP, interior design, upholstery, home textiles, fashion, activewear, stage backdrops, gaming tables. On the other hand, promotional products and other solid substrates such as glass, ceramics, plastics, slate, metals … really any surface that can take a polymer coating.
… ink is water-based and was developed for DTG (direct-to-garment) printing, in particular t-shirts, but is now the emerging ink technology for DTF (direct-to-fabric) where it is printed on to rolls of textiles for later manufacturing. After printing, the pigment is bonded to the fabric using heat (heat press or calendar). This is similar to dye sublimation, but it relies on the adhesion of the pigment to the fibres rather than dye absorption.
Pigment inks are not fibre specific which means they are very versatile as they can bond to natural as well as synthetic fabrics. They are typically used for cotton and poly-cotton blends in a plethora of applications, such as apparel, home textiles, interior décor. Pre-treated fabrics are recommended to enhance wash fastness and colour vibrancy.
… inks are printed directly onto textiles. Reactive inks have a different chemical binding mechanism to acid inks. For both inks, after printing the dye is fixed at high temperature through a steaming process and a subsequent washing process removes unfixed dye.
Acid dyes are suited to natural fibres such as silk and wool, as well as some synthetics like nylon. Reactive dyes are primarily used on cotton, rayon, viscose, linen and also silk.
… is an ink in which the main carrier is water, with colourants made from either dyes or pigments. Aqueous inks are non-toxic. For best results, the media should have a surface coating to absorb the ink and stop it from spreading before the carrier liquid evaporates.
Applications: paper and card, posters, photography, fine art, POS, indoor banners and signage, liner papers, treated canvas, corrugated, food packaging.