Wide-format Graphics: The nuances of digital textile printing

by all | 7 August 2014 1:30 pm

By Michael Syverson
Digital textile printing has been a growing market trend for at least six years now in North America, but within the last two years, especially, interest has reached an all-time high. Print service providers (PSPs) have educated many of their customers about the benefits of fabrics over other substrates, including lower costs for both drayage and longer-distance shipping, due to lower weight; ease of handling and storage; and permanency as reusable graphics. Most importantly, these customers have begun to take note of the esthetics of dye-sublimated fabrics, which tend to convey a perception of high quality.

Printing on fabrics is no longer a new concept. While there is still a continuing stream of education being delivered—both showing PSPs how to do it and explaining to customers why to have it done—most of the industry seems to have a good, basic understanding of digital textile printing in general. And many businesses have recognized opportunities for new profits as this market segment continues along a healthy upswing.

That said, there are still some areas of confusion, particularly given the growing range of printing technologies available.

Sublimation and non-sublimation
Digital textile printing in a traditional sense involves dye sublimation, a process that uses heat and pressure to convert solid dyes into a gas and permanently infuse them as colourants into a polymer-based material, usually polyester (see Sign Media Canada, May 2014, page 56). Today, however, it is also possible to print graphics on fabric using ultraviolet-curable (UV-curable) or durable aqueous ‘latex’ inks.

With dye sublimation, the fabric retains its look and feel, sometimes referred to as its ‘hand.’ The other types of fabric printing are not comparable in this respect, as they place ink onto the surface of the substrate, rather than permanently infusing it within the fabric. So, the resulting graphics cannot be washed, folded or handled in the same ways as a dye-sublimated piece. They also do not generally have the same high-end appeal.

‘Non-sublimated’ digital textile printing is typically used for specialized applications on non-polyester fabrics, like cotton or canvas, where dye sublimation is ineffective. It may also be adequate for many shorter-term printing needs.

Dye sublimation remains the optimal production method for retaining the esthetics and other benefits of fabrics along with image permanence. This is important for signmakers to keep in mind as they consider how to respond to increased market demand for printed fabric output.

Direct and transfer
To add to the confusion, there are two basic methods for printing with dye sublimation inks onto fabrics: transfer and direct.

The most common method, traditionally, has been to print an image onto transfer paper and then sublimate it onto a coated or uncoated polyester-based textile. In the direct process, on the other hand, the image is printed onto a coated fabric and then sublimated, without the use of transfer paper.

The advantages of transfer and direct sublimation are still being debated within the industry today. While it is certainly possible to argue about the quality of output from each method, however, the differences between them are much more nuanced than those between sublimation and non-sublimation printing. The choice of which to use will depend on the capabilities of the print or sign shop and the types of printers under consideration.

If a sign shop already has a heat-transfer press, for example, then it would make sense to continue with transfer-based dye sublimation printing capabilities, since stand-alone heat presses generally run at higher speeds than printers.

Other considerations reflect workflow preferences and specific application needs. Some signmakers, for example, prefer to set up a printer profile once for a specific paper and then only change settings on the heat press for different polyester-based fabrics. Others are concerned about the additional expense of the two-step transfer process, as they must buy the transfer paper. The playing field is slightly levelled because direct sublimation requires coated fabrics, which are more expensive than the non-coated fabrics that can be used in transfer sublimation—but the addition of paper is still more expensive at approximately 12 cents per square foot, compared to the additional three cents per square foot for coated instead of uncoated fabric.

If a sign shop has very specific needs for backlit graphics and flags, then it may make the most sense to use direct sublimation, which offers the advantage of a heavier ink load for these applications. With flags, for example, dense ink is typically required to show through both sides. And with backlit graphics, greater ink density means improved colour integrity when light is shining through.

For more precise and detailed graphics, on the other hand, transfer sublimation offers a slight advantage, with little to no bleed when laying ink down on well-profiled transfer paper.

Fortunately, there are some printers on the market today that allow PSPs to choose the best process on a project-by-project basis, supporting both direct and transfer sublimation. Indeed, this flexibility has quickly made these presses among the most commonly installed across Canada and the U.S., at least in the industrial 3-m (9.8-ft) wide category.

In this sense, the industry is balancing the overall market interest in fabric graphics with recognition of the importance of printing versatility.

On-board and in-line
Another advance in dye sublimation printing has been the recent innovation of supporting true heat press sublimation on-board the printer, making the machine an ‘all-in-one’ unit. This is referred to as ‘in-line’ sublimation.

In the past, some textile printers promised on-board sublimation by passing the fabric near a coiled heat source during substrate transport. This was not true dye sublimation, however, as there was no actual contact or pressure and the coils could not generate sufficient heat without the risk of damaging the substrate. The resulting graphics were not water-resistant off the printer and ink could bleed from the print. This necessitated additional steps to fix the final images, including washing and steaming to remove any excess ink that had not been properly sublimated.

Some newer all-in-one printers instead feature a true on-board heat press calender, ensuring the dyes are fully sublimated into the fabrics.

Ink developments
As elsewhere in the sign industry, the wide-format printers used for dye sublimation have seen much progress over the years, in terms of faster speeds, greater efficiency and higher-quality output. Dye sublimation inks, however, have been slower to evolve.

In the past, solvent- or oil-based inks were common for wide-format dye sublimation, neither of which were environmentally friendly, colour-vibrant or particularly easy to work with. Smaller printers used water-based inks, but were generally very slow and used the afore-mentioned coil-based heat systems, which left many steps to be completed after printing.

Today, however, there has been much progress in water-based inks for larger printers, achieving a vibrant colour gamut and greater batch-to-batch consistency. Compared to earlier options, these inks offer a higher pigment load, higher yields and lower cost per litre.

Finishing
If there is one area of the fabric printing business that is still somewhat lacking in proficiency, it is finishing.

[6]One of the strongest selling points of fabric graphics is the ability to form them in almost imaginable shape with ease, beauty and seamless appearance. This ability, however, has not tended to be part of a typical sign shop’s skill set.

One key is to plan for finishing right from a graphic’s conceptual stage. Specifications for sewing, stretching and framing should be worked into the design from the start so as to take into consideration such factors as shrinkage and skewing.

Sign shop employees may be intimidated at first by the need for specialized skills and, indeed, fabric graphic finishing should not simply be left to an existing print production crew without the right training and tools. With the right investment in a dedicated finishing department, however, a sign shop can certainly build sufficient knowledge and expertise to provide high-quality finishing in-house as a lucrative part of the business, rather than outsourcing it.

Customer trends
As awareness of the high-quality appearance and easy manageability of fabric graphics, many types of customers are fuelling this industry trend.

In the trade show business, for example, exhibitors are painfully aware of the costs for drayage and shipping from show to show. The difference in weight between the typical vinyl or rigid graphics and lighter fabric graphics is extraordinary, but another advantage of the latter is the ability to use the same eye-catching booth imagery for multiple events, rather than having to reprint graphics for each show.

This convention and exhibition market tends toward the look and feel of soft knit materials, which offer the four-way stretch capabilities needed for silicone-edge graphics (SEG) and tension frames. They also generally offer a matte finish, which is desirable to prevent glare on signs under all of the lighting of a large exhibition hall.
Fashion and beauty product retailers are also switching to the richness, beauty and feel of fabric graphics to reflect their sophisticated and elegant brands. For many point-of-purchase (POP) display applications, retailers are drawn to the visual effects of backlit graphics, so translucent textiles are being designed accordingly.

The hospitality, museum and theatre décor markets are also strong customers of fabric graphics. And while sign shops continue to mainly focus on commercial wide-format graphic applications, there are other markets the same equipment could help them serve, particularly in the future. Already, such items as upholstery, apparel, drapery, curtains, pillows, carpets, backdrops, custom furniture and other elements of interior décor are being decorated using digital textile printers, though usually in very short runs and one-offs. Just as digital printing has already taken over and continues to dominate many areas that were once served by offset and screenprinting systems, so too is there enormous potential for digital textile printing to take over much of the textile screenprinting and rotogravure markets.

A maturing market
As digital printing technology continues to mature in terms of speed and capacity—and as PSPs gain stronger knowledge of new processes—there is room to absorb market share from traditional textile businesses. Fabric graphics have a high perceived value, which is opening doors for sign shops to serve higher-end clients and increase profit margins.

This is especially true at this early stage of an emerging industry, when fabric graphics are not as heavily commoditized as vinyl banners and other signage applications. With profitability and demand for better products driving improvements in digital imaging and printed output, innovations will continue for years to come.

Michael Syverson is director of special projects for PrinterEvolution, which develops a range of textile printers. For more information, visit www.printerevolution.com[8].

Source URL: https://www.signmedia.ca/wide-format-graphics-the-nuances-of-digital-textile-printing/

---