Textile printing presents both opportunities and challenges. It is possible through a variety of methods—dye-sublimation (dye-sub) direct, dye-sub transfer, and direct to print. Factors such as ink, mechanical systems, image fixation, and media transport each play a role in perfecting textile print applications. Media selection and proper profiling further optimize print quality when it comes to printing onto fabric.
Print service providers (PSPs) offering textile printing services manage output quality through color management and utilizing specific tools featured within various print engines.
When printing onto textiles, the process used dictates compatible media and ink options. While printing onto textiles can be similar to printing with traditional substrates, nuances do need to be addressed in order to ensure high-quality output and maintain efficiency.
“Strictly from a printing perspective, the processes are very similar,” admits Mike Wozny, strategic product manager, EFI. The ink jets directly onto either fabric or paper. A key difference is when dye-sub is used. “In that scenario, an additional process—sublimation—is required. The sublimation process imbeds, or infuses, the dye into the fabric,” he adds.
While direct digital printing is an option for outputting onto fabrics, often dye-sub comes to mind when printing textiles. Dye-sub ink can be printed directly to the textile or transfer paper. Both direct and transfer dye-sub methods require a heating unit. Primarily, dye-sub is an aqueous process.
“Even though the technology has been around for a while, a beautiful digital image on a textile still stops people in their tracks,” says David Hawkes, group product manager, Roland DGA Corporation. Dye-sub produces very high print quality and marries it to the unique properties of the textile being printed on. “The good news is that people are willing to pay more for stunning effects. The bad news is that there is a little more work involved with dye-sub, especially transfer dye-sub. But the pain is worth the gain,” he adds.
With transfer dye-sub, a tighter image resolution is achieved. “There is a certain amount of dot gain when printing directly onto fabrics, regardless of the method. The transfer paper minimizes this. As a result, this process delivers high image resolution,” says Hawkes. Transfer dye-sub is ideal for textiles or any application where fine details are viewed up close.
In the case of direct dye-sub printing, the inks are printed to polyester-based fabrics for the best results. This direct printing does not resemble the intended appearance, as the final desired state is accomplished by the use of heat and pressure during the calendaring phase. “The calendaring phase, sometimes referred to as fusing, converts the deposited ink from solid form to a gas form. In its gaseous state, the dye is permanently bonded to the receptive polyester fabric it is in contact with. This conversion also transforms the relatively under saturated color of the inks into bright, saturated colors,” explains Kevin Currier, application solutions manager, Durst Image Technology US LLC.
Tom Walsh, product manager, :Jeti, Agfa Graphics, points out that while there are many similarities between printing on traditional solvent or UV-curable roll-to-roll media, there are some critical differences when directly digital printing onto textiles. For starters, the entire system has to be designed with water-based ink and the transport of textile media in mind.
Image fixation is also important. Disperse dye inks offer brilliant saturation when optimized and the fixation step is key. “All of the processes used in textile printing must be carefully managed for consistent results,” recommends Walsh.
Many textile printers include features that offer better handling. Media transport presents one of the biggest differences between printing onto traditional media versus fabric. Systems should be designed for optimal tensioning, stretch/shrinkage reduction, and wrinkle free and accurate stepping transport.
Because fabric does not have the same dimensional stability as traditional media—such as paper or vinyl—advanced feeding systems are important. Keith Faulkner, president, Splash of Color, Inc., says a system of rollers and dancing rollers to which weights can be added is desirable to maintain constant tension during the printing and sublimation process.
“The feeding system is the most important aspect of textile printing,” states Jason Bartusick, president, Media One Digital Imaging Solutions, LLC. “If anything is off, the prints are trash,” he emphasizes.
Media One offers textile printers manufactured by d.gen, Inc.
Digitally printed textile applications are often viewed up close, therefore quality is important. This is true with clothing, exhibits, and soft signage point of purchase.
The amount of ink used affects image quality, dry time, durability, and cost. Controlling ink lay down is achieved mainly through media profiling. Proper ink limits are set within the color profile in order to produce sufficient color intensity while maintaining a crisp image.
“A profile is worth its weight as it simplifies your life by providing the printer settings required for a product,” explains Hawkes.
Ink lay down is just as important as any print application. “The difference about textile printing is if you lay down more than the textile can absorb and fixate, you’re going to get ink rub off,” warns Bartusick.
EFI’s Wozny adds, “the more ink that is laid down the higher the image quality—richer colors, better show through. The art in the process is putting a lot of ink down, but not too much where you lose detail throughout the image.”
In addition to profiles, media selection is essential for controlling quality. Faulker suggests selecting a fabric that accepts ink well and is not susceptible to wicking.
Textiles, like any other printing media, require specific printing parameters and the qualities of the different textile options vary according to their surface treatment, physical properties, and final application, point out Roman Barba, research and development engineer, latex printing technology, large format production, and Pere Canti, research and development lab tech lead, latex printing technology, large format production, Hewlett-Packard (HP).
Managing color is a common concern. A combination of color management tools, experience, and proper profiling techniques help PSPs master color vibrancy and consistency.
When printing with dye-sub direct ink, the printed color swatches must be sublimated before the color patches are read, explains Faulkner. “Sometimes heavily textured fabrics present challenges in making accurate readings,” he adds.
Barba and Canti note that textiles include a broad family of substrates, such as knitted, woven, warp-knitted, non-wovens, canvas, cotton, and polyester, with very different characteristics among them. The most important feature in terms of color management, however, is whether the intended use is as a reflective or transmissive media. “This determines how the color resources are created,” they add.
The role of texture is also a consideration. A wide aperture spectrophotometer helps provide more consistent readings. “Care needs to be taken to optimize the transfer application before profiling to maximize gamut, output, and performance,” notes Randy Anderson, product marketing manager, Mutoh America, Inc.
Mutoh’s ValueJet 1628TD, 2628TD, and 1638W printers utilize dye-sub and textile inks with transfer dye-sub processes.
Tools for Textile Success
Digital textile printer manufacturers incorporate features into equipment and bundle complementary solutions to ensure optimal performance. In addition to hardware components, such as transport systems and heating units, RIPs are a key component in the printing workflow.
Agfa’s :Jeti 3324 Aquajet incorporates critical features, particularly in the ink type, mechanical system design, image fixation, and media transport for optimal textile printing compatibility. The water-based dispersed dye ink allows for rich saturated colors and bleed-through printing for flag material. A built-in curing oven is designed to vent vapor and eliminates the need for offline calendaring or curing.
Durst offers its Rhotex 320 direct dye-sub printer, which utilizes water-based disperse dye ink. All profiling processes for Durst Rho printers are accomplished by use of the built-in EasyMedia module of Caldera RIP software. The EasyMedia program enables straightforward generation of ICC profiles for UV-curable, flexible, and rigid materials. Built-in controls for light inks make fabric profiles effective and efficient.
EFI offers transfer and direct dye-sub capabilities with its VUTEk TX3250r and direct digital print with its VUTEk QS3250r, VUTEk GS3250r, and GS5000r. The company provides a range of color management features within the EFI Fiery XF RIP, which are not specific to transfer or direct dye-sub printing. Fiery XF is designed to help produce great color, including the optional Intelligent Clean Colors, which uses the printer’s color gamut to its fullest potential.
HP’s portfolio encompasses solvent, UV, and latex printing technology. In particular, HP Latex Printing Technology is designed with the capability to print directly onto fabrics without a liner. Color performance is ensured through the use of media profiles that contain color specific resources such as ICC profiles, in addition to other critical parameters that are specifically tuned to each media or fabric.