Digital Textile Printing: A Primer
Digitally printed textiles provides a lucrative medium for many applications, including soft-signage, apparel, interior environmental graphics, and much more! There are several choices of textile printers on the market so it’s important to know the options and differences when considering a purchase. Digital textile printing uses several types of inks, each designed for a specific type of fiber used to make the textile fabric. The intended application and media preferences will dictate which inks can be used.
Dispersed dyes are specifically used for artificial fibers such as polyester, acetate rayon, poly Lycra, and acrylics. The dyes have the ability to infuse into the fiber, producing an extremely soft feel. Dispersed dyes are direct printed on to the textile and then processed through a heat press to fix the color.
A specialized form of dispersed dye is dye sublimation ink. Dye sublimation is always done on a polyester, polymer, or polymer-coated media, substrate, or fabric. With dye sublimation, the inks are printed on a transfer paper, and then transferred to the fabric by applying heat and pressure using a heat press or rotary calender. Dye sublimation can be used to produce a wide range of finished goods, not only fabric, but hard goods like license plates, mugs, tags, plaques, and metal signs which enables the user to offer a variety of products using one technology.
Although there may be some differences in the print characteristics for dye sublimation transfer versus direct disperse, it can be argued that direct disperse dyes is a more sustainable print process, in that it eliminates the consumption and disposal of transfer paper. Printing with direct disperse dyes increases the spread of the ink (dot gain) and can produce less color vibrancy. Keep in mind either method requires energy to generate heat needed to initiate the sublimation of the ink.
Different Inks for Different Textile Printing Applications
Pigment is the most widely used colorant in digital inkjet inks. They use extremely fine colored pigment powders that are suspended in a liquid carrier in order to be used in an inkjet printer. The fabric must be coated/treated with a receptive layer that bonds with the ink. Pigment ink is being touted as a single solution for all fiber types; however, continued improvements on the fabric coatings must occur. There is plenty of R&D being done on coating chemistry which will propel pigment and its use in textile printing.
Solvent inks are acceptable for textile printing for specific uses. The nature of the ink makes them suitable for display applications only, they are not for wearables or for use in furniture upholstery. Since the ink sits on the surface of the fabric, there is greater chance of abrasion and scuffing of the image. Solvent inks are also used for manufacturing of temporary carpets for custom floor displays. Most any solvent-based printer can print textiles that are compatible with solvent-based ink systems.
UV curable inks are used in roll-to-roll printers and can be used for the production of printed textiles (window displays, feather flags, soft-signage). Again, these products are for display/exhibition purposes only, not for being worn. The longevity of these prints depends on the environment in which they are displayed. Outdoor longevity is comparable with the solvent ink versions of the same print (<2yrs.). UV ink is the most expensive ink of all the ink chemistries discussed here.
Printers using Latex ink, have a wide range of compatible uncoated fabrics and textiles available. Latex ink has very good adhesion characteristics on a variety of textiles, suitable for indoor and outdoor applications and latex can reach markets that are unattainable with other chemistries’ (hospitals, child care). Items printed with latex are, again, for display applications only.
Other digital textile inks include acid and reactive dyes; however, these chemistries are used mostly for apparel applications. Acid dyes are used on protein fibers like silk or wool and the fabric must be pre- and post-treated (steaming and washing). Reactive dyes are used on cellulose fibers like cotton and also require pre- and post-treatment.
A variety of fabric types are used for soft signage applications, with polyester currently the most common. Other available fabrics include canvas, cotton/polyester blends, satin-finish polyester, and cotton.
Digitally printed textiles are estimated to be between 2%-5% of the total printed textiles market (estimated at $146.5 billion in 2018 by Grand View Research). Digital printing will continue to surge and augment analog printing platforms due to its high consistency, continuous printing, cost-effective production, and design versatility, not to mention savings in shipping costs and installation. Compare shipping a roll of printed vinyl (package size, weight) to that of a printed textile that can be folded and placed in a box. Digital textile printing offers high-resolution printing that produces thousands of color combinations. The technology uses less ink, electricity, and water as compared to analog platforms and space requirements for the printers is far less. The increasing penetration for soft-signage and advertising are expected to increase the demand for digitally printed fabrics.
Johnny Shell is the Vice President of Print Technology & Training for SGIA. In this role, he is responsible for developing educational opportunities and industry-focused products and services for the advancement of the printing industry. Johnny is a printing professional and recognized industry expert with 30+ years’ of experience in apparel, graphics, commercial, and industrial printing applications. Shell conducts numerous workshops annually and his articles appear regularly in top industry publications.