Technological Factors

Whether a PSP goes for a user-friendly device or not, there are other considerations. Such as which method is best for specialty and signage applications. 

Directly printing onto fabric means less steps, with no transfer paper or heat presses involved. However, if you direct print onto fabrics with eco-solvent or solvent ink, coated fabric is necessary to maintain image quality.

Direct dye-sub printing to fabrics allows users to control stretch by including a heat press in the same machine. Generally, fabric must be coated to minimize dot gain. Fabrics are printed first, then taken to a sublimation unit to create the final graphic. Transfer dye-sub means the image is printed on special transfer paper and then sublimated onto the fabric using a heat press.

“Sign-based applications can benefit from both direct as well as from transfer printing; it all depends on the balance between cost and quality and the production and application requirements,” shares Biemans.

HPS’ most popular textile printer, targeted toward the sign and display market, is the ColorBooster XL—a 3.2 meter six-color system. It is specifically designed for textile printing and includes a built-in airco system for humidity and temperature control, which allows for precise and consistent reproduction.

Factors such as dot gain and fabric texture are huge components when determining whether a process is best for specialty applications; where detail is crucial.

“When selecting any of these methods for a specific application, it is important to understand the differences in workflows and the overall image quality generated by each,” cites Fernando Catania, product manager, Roland DGA Corporation.

Roland’s sublimation VersaArt printers, the 64-inch RS-640 and 54-inch RS-540, require Roland’s BU-2 high-capacity ink system and SBL2 sublimation inks for sublimation printing. They print up to 342.6 sf/h and support unattended production. Optimized with a take-up system, media rolls of up to 66 pounds are handled.

The best applications for direct printing onto fabrics are large and grand format signage, which are generally viewed at a distance and do not require precise detail. Transfer sublimation printers are recommended for shops focused on specialty applications where fine text and other elements need to be viewed up close.

“It depends on the fabric type, everything except polyester should be direct printed. There are special coatings for some of these specialty-based materials to help control dot gain and some may require special post treatments to optimize appearance and performance,” explains Randy Anderson, product marketing manager, Mutoh America, Inc.

Mutoh’s ValueJet 1628TD and 2628TD are dual printhead, dual ink printers loaded with direct print ink in one printhead and transfer in the other. This makes the machine capable of printing with a wide array of sublimation products.

Due to the need to coat certain fabrics before they are printed on directly with UV or solvent ink, these have a harder, more rigid texture. Faulkner suggests that dye-sub is the preferred printing method over direct print for specialty applications such as apparel and furnishings because the resulting product will have a softer hand or texture.

The HeatWave DFP-74 from Splash of Color is a direct to fabric sublimation printer, allowing users to print directly to polyester materials and then sublimate the printed fabric in a single roll-to-roll operation. The system is designed to maintain constant tension while being fed with precision stepper motors. A cork covered roller is available when printing on stretchy fabrics such as Spandex. A quartz-heated calender ensures fabrics are sublimated at a consistent temperature, to maintain similar color across the width of the fabric.

Fabric shouldn’t be a limitation in deciding whether direct or dye-sub is a best fit; especially as over the last few years manufacturers have created pre-treatments that resemble a softer hand. Read more about fabrics for digital print in this month’s article, Give Fabrics a Hand.

Sublimating Heat

Heat presses are essential to the sublimation process, whether they are separate devices or integrated into the print system. When sublimation inks are heated, they quickly form a gas that permeates and permanently dyes the fabric. This is in contrast to solvent and eco-solvent inks, which bond to the surface of the media.

Whether printed directly on polyester fabric or transfer paper, dye-sub ink must be heated between 180 and 190 degrees Celsius. It is at this temperature the dyes pass directly from a solid to a gaseous state and bond permanently to the polymers on 100 percent polyester fabrics.

David Gross, president, Condé Systems, Inc., cites two types of heat presses—flat and rotary; also referred to as calendered. “Flat presses are used for most types of sublimation, both hard and soft substrates and many apparel applications. Rotary or calendered presses are similar to large drum laminators. These presses are ideal for banner and large soft signage applications. A roll of paper is printed and then married to the fabric by running it through a rotating hot drum.”

A Fitting Retreat

Group Imaging, based in Mesa, AZ, began in 1996 with a focus on photo lab work. As the company grew—at press time it was expanding into a 21,000 square foot space—they began to dabble in dye-sub printing. Initially, they purchased a Mimaki JV4 dye-sub transfer printer and a 67-inch DigiHeat heatpress from DigiFab Systems, Inc.

About 50 percent of Group Imaging’s work is fabric printing. Many of the jobs utilize Fisher Textiles, Inc.’s products. 85 percent of its client base includes churches and parachurch organizations, such as Compassion International.

In December 2010, Group Imaging turned to Mutoh and purchased a new ValueJet 2628TD, which prints on fabric up to 104 inches in width. The shop had previous experience with Mutoh products, namely five eco-solvent and solvent printers, and felt confident in its newest acquisition. The device prints directly to fabric or via dye-sub transfer depending on the type of ink placed in the machine. This is one of the reasons why it was purchased. As Jeff Burris, president, Group Imaging, says, it allowed him and his staff to experiment with direct to fabric printing without purchasing a dedicated printer.

After installing the ValueJet 2628TD, Burris shares that the learning curve was low. After years of working with Mutoh devices and dye-sub printers, his 16-person team was able to steer clear of any surprises.

A Methodology to Textiles

Working with industry trade organizations and taking classes, attending Webinars, and visiting annual shows are excellent ways to become familiar with digital textile printing. PSPs learn the various technologies, ink sets, and fabrics and are provided with an up-close trial-like experience before making an investment.

Signage is an easy addition to an existing portfolio thanks to versatile printers and a small learning curve. Those looking to add apparel and furnishings to their offerings should consider the importance of working with a dye-sub transfer machine, as it provides high-quality graphics. However, acknowledging the subtle nuances of this device; from additional steps to more waste, is important. PSPs looking to enter digital fabric printing should assess their workflow and see which application—whether specialty or signage—is a fit.