A common misconception regarding dye-sublimation (dye-sub) is the ink. Between both direct and transfer processes, the average person may assume that each ink is entirely different.
In reality, the contrasts between dye-sub direct and transfer are more in the physical make up of the printing device and not necessarily the chemical consistency of the ink set.
With the advent of transfer dye-sub, print service providers (PSPs) and vendors looked to further the ease of use associated with the sublimation process. This included adding internal fixation units, as well as widening the range of compatible substrates, sublimating on textiles and unique surfaces such as glass or wood. The main difference between dye-sub transfer and direct ink lies in the required quality and color gamut of the job.
In both instances, sublimation ink is considered disperse. This is because when applied, ink color particles spread throughout the substrate. Transfer and direct dye-sub ink are dispersed to either transfer paper or directly to the intended final substrate, respectively.
It is this difference that Ken Bach, USA development manager, Afford Industrial S.A., argues is the only variance between the processes. When applied directly to a coated fabric, he explains, that coating holds the ink drop in place until sublimation occurs using an internal fixation device. Conversely, transfer paper is designed to hold a ink drop until it is taken into an external heat press and sublimated onto a secondary substrate.
Transfer paper compared to fabric is where the minute formulations in the ink sets lie. “Some components when printed to paper stay in the paper during the transfer process. If printed directly, these components would alter colors. The formulation is adjusted in direct print ink so that what is printed on the fabric only shows color,” shares Ashley Scoville, marketing coordinator, Sawgrass Technologies, Inc.
This small difference determines the level of quality of the final product. Dual ink sets are now available that offer similar results when printing direct or to transfer. But, according to Stephen Woodall, product manager – digital textile and coding inks, Nazdar, “for the high-end applications where density of color and quality of print is paramount, an ink designed and formulated for transfer applications still outperforms a dual ink.”
The Oldest and the Wisest
Transfer ink arrived on the scene prior to direct dye-sub ink. As such, it is still used on a daily basis for those looking for a high-quality product. Basic uses include signage, apparel, and custom textiles—all applications that require ink to adhere well with superior color visibility.
Looking to build on transfer’s footprint-heavy environment, direct was introduced as a more simplified process. It saves time and money by eliminating the step of printing onto paper and then transferring. With inline fixation units, PSPs erase footprint space as well.
Direct dye-sub is ideal for flag and banner applications; such as point of purchase (POP) and point of sale, because of its excellent two-sided penetration. While this is a great feature, direct cannot rival transfer in regards to color vibrancy.
Karla Witte, VP of product development, INX Digital International Co., explains that as vendors evolved and enhanced dye-sub ink sets, they learned as they went.
“The first type of digital printing was used for small runs on items like ties and scarves. It changed the way the industry viewed printing on these types of products,” she says. Today both direct and transfer excel in large runs of multi-faceted applications, simply depending on the substrate used and the process at hand.
In addition, dye-sub ink is finding success in the grand format sector. For example, Sawgrass recently introduced a water-based disperse dye ink for grand format printers referred to as SubliM Direct SPS.
The ink is formulated for high-speed, grand format machines and provides no sacrifice in color. It is available in CMYK and ideal for applications such as exhibits, flags, POP, and soft signage utilizing polyester fabrics.
Switch Out to Plug In
With such similarities, transfer and direct dye-sub ink can feasibly be used in both transfer and direct devices. This is because they are designed to utilize the same type of printhead.
“The hardware required to sublimate, including the components that store, process, and ultimately print the ink, are similar regardless of whether the device is a direct or transfer machine. Accordingly, transfer dye-sub devices are capable of handling direct dye-sub inks and vice versa,” shares Fernando Catania, product manager, Roland DGA Corporation.
A perfect example of such ink is Graphics One, LLC’s GO Xtreme Dye Sub Ink, which is specially formulated for both direct and transfer printers. There are three variations, including Xtreme Color, Xtreme Eco, and Xtreme Dots.
Xtreme Color offers a high color gamut with true black. Xtreme Eco provides an environmentally friendly dye-sub ink that meets Oeko-Tex standards. Xtreme Dots features dot gain control for detailed dye-sub printing.
Another option, Mutoh America, Inc.’s ValueJet printers, offer a two printhead/dual ink system that allows for the use of transfer in one printhead and direct in the other. According to the vendor, this enables printing both direct and transfer dye-sub ink on the same material for better penetration onto the media.
However, if we circle back to the substrate theory, the real problem in switching between inks on one type of printer becomes media handling. Direct ink is formulated for pre-coated fabric, as previously mentioned, so it does not function as well on paper. Issues that can arise include cockling, lack of dot formation, and poor drying characteristics.
These same challenges lead to material waste as well as time and money lost in the print process. For an inexperienced PSP it is difficult to easily remedy many of these hurdles.
“The chemistry has to be tailored to the substrate and the transport device. Otherwise you get improper spreading, smearing, and other problems. The less obvious challenge is media handling for paper and other relatively stable materials generally won’t work for textiles. It comes down to efficiency versus flexibility. Some delicate fabrics will wrinkle or tear in a direct machine,” adds Nate Hine, manager, :Jeti printheads and inks, Agfa Graphics North America.