By Olivia Cahoon
Textiles are booming with a range of applications across many industries, from entertainment and fashion to sign and display. Several digital options are available when printing to textiles including acid, reactive, pigment, and direct or transfer sublimation. UV and latex inks are alternatives if the textile is properly treated prior to printing.
Each textile printing option offers its own benefits depending on the market and industry, as well as the fabric type. Aside from that, print service providers (PSPs) investigating available options should consider space requirements and printheads.
Dye-sub printing involves a solid dye converted directly to a gas—avoiding the liquid phase. The gas binds to the polyester and dyes the fabric. This type of technology is available in direct and transfer printing methods.
Dye-sub technology is popular for textile printing because it offers permanent full-color, digital printing. “Sublimated fabrics are vibrant in color and the imprints will not crack, peel, or fade with wearing and washing,” shares Robin Kavanagh, public relations manager, Sawgrass Inc.
The inks are associated with polyester, blends, and similar polymers for several markets including photography and fine art, as well as pre-manufactured garments, fabric bolts, banners, and flags. “Dye-sub is floor mats, tiles, carpet, personalized tables, chair, canvas prints, banners, awards, curtains, and couches,” comments Matt Gusse, VP sales and marketing, Advanced Color Solutions.
Despite its broad use, Kavanagh finds the largest advantage of dye-sub is that it gives companies and individuals the ability to produce a range of sublimated products. It offers a variety of available papers and films for objects from printed mugs and fabrics to photographs and phone cases.
Transfer & Direct
Primarily used for polyesters, most textile dye-sub printing is completed with the transfer method where paper is printed and heat transferred to a polyester base. Transfer typically yields vibrant colors and sharper detail than direct technologies.
“Perhaps the best thing about transfer dye-sub is that it works on virtually any polyester surface that accepts sublimation. The fabric needs no pretreatment—only heat and pressure for sublimation,” shares Randy Anderson, product marketing manager, Mutoh America, Inc.
Tom Wittenberg, HP Americas large format strategy, planning and content manager, sign and décor, HP Inc., believes polyester-based fabrics are more popular than ever before. “Polyester fabric demand has continued to grow, in many applications surpassing the demand for cotton As polyester fabrics gain wider adoption, dye-sub printing grows as well.”
Direct sublimation works well for backlit and flag materials as direct printing allows for front-back saturation. According to Anderson, the direct method necessitates a trough to collect excess ink and keep it from smearing on the printed fabric’s backside. Direct printing of four-way stretch material also needs a sticky belt to hold the media flat and secure. Most fabrics for direct printing requires some form of pretreatment as well to control wicking and ink bleed.
Acid inks are used with pretreated fabrics and are printed directly to the textile followed by steaming. This printing process is well suited for garments and flag printing.
Acid inks are applied to protein-based materials such as nylon, silk, and wool. Because of the vibrancy, they are used for scarves or swimwear. Tim Check, product manager, professional imaging, Epson, says the printing process consists of numerous steps, including fabric pretreatment, drying, printing, drying, steam fixation, washing, and a final drying step. It is not commonly used on plant-based fabrics.
According to Walter Gupper, sales, Sansara International, Inc., acid is the best ink for printing polyamide, silk, and other fashionable fabrics due to its excellent wash characteristics, light fastness properties, high color saturation, color-fixing rate, and image definition.
It’s important to note that acid dye inks do require a pretreatment for dot control as well as high-pressure steaming to complete the process. Following the printing process, the dyed fabric needs to be washed to remove excess ink and dried before use. “Acid dye rules the flag market, direct printing allows ink to penetrate the fabric and the steaming sets the ink so that two-sided flags can be produced in quantities,” offers Anderson.
Reactive inks contain dyes that create chemical bonds with cellulose when applied to pretreated fabric. They are ideal for apparel and other soft-touch applications due to extensive light and rub fastness.
Reactive inks are best used for dying plant-based materials like cotton, linen, rayon, and viscose—primarily in the fashion industry. Similar to acid technology, Check says the reactive printing process consists of several steps like fabric pretreatment, drying, printing, drying, steam fixation, washing, and a final drying step.
In reactive printing, Gupper shares that fabrics are typically coated before printing, steamed after printing to set the ink, and washed to remove the pretreatment and excess ink, which creates a reaction that dyes the fibers through the material. “It has the best color fixation, a variety of colors, and soft fabric surface.”
Because reactive inks rely heavily on a multi-step process, Anderson explains that it is one of the more expensive methods for printing to textiles.
Pigment inks are finely ground powders suspended in liquid carriers with binders. This process is suitable for a variety of fabric types and offers a straightforward printing process.
Depending on the fabric, a pretreatment may be required when pigment printing to ensure a durable bond, followed by printing and heat curing. In select applications, the use of a post-treatment liquid can add additional properties, suggests Check. For example, a post-treatment provides dress pants with added stiffness for easy creasing as well as stain resistance.
Pigment-based inks are applied to multiple substrates including cotton, linen, nylon, polyester, rayon, silk, and wool, while delivering good vibrancy and light fastness, shares Celine Tezartes Strauss, product manager, inks and consumables, Kornit Digital. The ink is also eco-friendly with options available that require no pre- or post-treatments for a quick printing process and small footprint.
“Pigments are most versatile for printing to different substrates, potentially requiring less machinery and a simpler, more eco-friendly process,” she offers. If space is an issue, pigments offer an ideal opportunity for small workspaces.
Similar to reactive and acid dyes, pigment inks are suitable for fashion as well as home décor and do-it-yourself design.
Roland Zimmer, VP sales North America, Zimmer Austria Inc., believes that in addition to fashion applications, pigment inks are also well suited for ceiling tiles, narrow fabrics, outdoor fabrics, panels, paper, wallpaper, and technical textiles such as sponges or non-woven materials.
Compared to dye-based inks, pigment’s color range and vibrancy tends to be slightly lower. Because pigment is a surface coating as opposed to a dye, Anderson says abrasion resistance and washability are also not as good. However, he believes pigments have better color fade resistance against UV than dyes, making it a preferred option for outdoor applications such as sun blinds or tents.
Like pigment printing, UV/latex technology uses surface-applied inks that require curing. UV/latex inks are available for printing to textiles if the textile is properly pretreated.
According to Mike Syverson, textile manager, North America, Durst Image Technology US LLC, printing UV ink to textiles is typically only for signage applications where dye-sub won’t suffice. “Latex inks can be used in home textiles although only in small volumes due to slower print speeds required for good results.”
UV/latex ink chemistry features high UV light resistance, which makes it suitable for outdoor fabrics and drapes where sun exposure is high. However, its chemistry makes it unsuitable for most apparel items. “There is a noticeable feel to the ink on the surface of the garment, which makes this poorly suited,” explains Check.
Narrowing the Search
Aside from fabric type and application, PSPs investigating available digital technology options for textile printing look to other critical areas such as costs, finishing methods, printhead technology, and footprint.
Space is arguably one of the most important considerations PSPs should be aware of before selecting a device. This includes sufficient space needed for the printer as well as the equipment that fixes the ink to the fabrics, including heat presses for dye-sub and pigment or a textile steamer for acid and reactive inks, shares Lily Hunter, product manager, textiles and consumable supplies, Roland DGA Corporation. Space is also needed for tables that lay out fabrics as well as sewing machines.
The PSP should also consider if cutting will be completed manually or with a flatbed device. If using a flatbed cutter, Hunter says additional space is required. Other considerations include ventilation and how the various machines are situated.“
Space requirements and costs are determined by looking at decoration forms as well as intended quantities. For example, Kavanagh suggests PSPs adding logos, numbers, and other types of decorations to apparel items select a desktop system with a 25-inch maximum width.
For fully customized shirts and cut-and-sew applications, a mid-format system with a wider manual or pneumatic press may be more appropriate. However, she warns that more space and electrical power are needed to accommodate the equipment.
Imprinting fabric bolts or other large textile applications typically requires a wider format printer, likely with an integrated calendar press. For this setup, Kavanagh says a warehouse or large industrial space is most appropriate. “Of course, costs for each level of production increase, not only for equipment, but also space, production supplies, and utilities.”
Depending on the printing method, PSPs should pay attention to the device’s printheads. For example, when it comes to pigment printing Zimmer says most printheads are not suitable for textiles. “Many manufacturers claim to have an ink circulation system in place to reduce risk of sedimentation of solid particles,” he shares. “This means circulation only takes place in the ink tank system.”
For pigment printing, PSPs should consider printheads that offer a 100 percent ink circulation system including the ink tanks, ink supply lines, printhead, and the microchannels passing the piezoelectric actuator. According to Zimmer, this system guarantees the ink’s water cannot evaporate and therefore change the ink’s physical properties. Ink circulation also reduces the risk of ink drying and eliminates the need to force flush printheads.
What Fits Best
A variety of digital technologies are available when printing to textiles. With so many choices, it is daunting for PSPs to determine which options better suite their business. Luckily, PSPs can look to what fabric types they intend to print on as well as the industries they serve. If further help is needed, spacing requirements, finishing practices, and post-treatment options are also useful considerations.
Oct2019, Industrial Print Magazine