Conventional vs. Direct Dye Sublimation

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Textiles seemed to jump out as the substrate of choice during the past year. Naturally, the increased popularity of these printable materials has inspired debate, particularly in regard to conventional vs. direct-print dye sublimation. Dye sublimation is quite unlike any other wide-format inkjet printing process. It produces colors that are wildly vibrant and can retain great detail. This month, we’ll examine the differences between dye-sub technologies and consider the benefits and limitations associated with each.

 

The basics of conventional and direct dye sub

The conventional digital dye-sublimation process involves using a digital printer to produce an image in reverse on a coated transfer paper. Heat is then used to transfer the image from the paper onto the final substrate, which can be a polyester fabric or other polyester or polyester-coated material. The sublimation inks may be aqueous, solvent-based, or oil-based, and the inks are generally provided as four-color process plus additional colors to increase the gamut.

Sublimation refers to the process under which a substance transitions between solid and gaseous states without going through a liquid stage. The misting or fogging action of dry ice when it is exposed to room temperature is a common example of sublimation.

Sublimation inks are transferred from the carrier sheet to the final substrate using a heat press operated at approximately 356-410°F (180-210°C). Under high temperature and pressure, the dye turns into a gas and penetrates the fabric and then solidifies into its fibers. Dye-sub ink immediately transforms into gas when heated to about 390°F (200°C). The heat also opens up the pores of the polyester or polymer-coated media, which then allows the gas to permeate the material. Removal of the heat source causes the sublimation ink to revert to a solid form and the polymer pores to close, encapsulating the ink within the polymer. If done correctly, the image will never fade, crack or deteriorate as it literally becomes a part of the substrate itself.

While the conventional dye-sub method digitally prints to a paper transfer media and then transfers the image to the final fabric, the direct dye-sublimation method prints directly to the final substrate and uses no transfer paper. The fabric for direct dye sub usually features a special coating, and the printed dye-sub inks basically float on this coating. When the fabric is exposed to heat, usually on an inline heating unit, the sublimates into the fabric to form a durable image.

Direct-to-fabric printing may be a more cost-effective process that results in better ink bleed-through on the fabric; however, using transfer paper yields better image quality, especially in terms of detail and edge definition. Transferred graphics provide true, photo-realistic fidelity because fabric doesn’t have the same fluid uptake as paper. But a direct solution makes sense for flags and other applications that call for saturating fabric to achieve bold colors on two sides.

One of the main advantages that both methods of dye-sub printing have over UV and solvent inkjet printing is their ability to print a superior color gamut. The vibrancy and intensity of sublimation inks gives P-O-P designers great options.

The cost of equipment, image saturation and quality, consumables costs (ink and fabric), and labor/versatility are among the considerations to keep in mind when deciding whether to go with conventional or direct dye sublimation. Some printing devices require the use of a heat press, while others feature their own onboard heating devices that eliminate the need for human intervention. A printer and heat-transfer device are minimum requirements for getting into the conventional dye-sub game, and costs grow exponentially for both as they get wider. The same price concept applies to direct dye sub, where again you can buy an inline or all-in-one system.

 

Consumables

Dye-sub applications have been around for many years, and vendors in this industry have painstakingly refined the materials that are associated with this technology. Water-based and solvent-based dye-sublimation inks are most commonly used in the conventional process. Water-based inks typically produce finer details and higher quality images with better color.

While water-based sublimation inks have struggled in wide-format output because the high-volume of water these inks contain inevitably saturates the transfer paper and causes cockling. Water breaks down the organic material in the paper, which results in the waviness. That said, printers have progressively delivered better results from water-based inks at larger and larger sizes with newer papers that allow for greater ink deposition.

Ink makers introduced solvent-based dye-sub inks to help dye sub go grand format. It’s one of solvent’s advantages. Another is excellent print stability and high color density. Many of these super-wide, solvent-based, dye-sub printers can be converted from dye sublimation to conventional solvent inks for vinyl without too much trouble. In addition, the color gamut of the solvent-based dye-sub inks is very rich and the black is very strong, which provides the pop many applications require. The cost of solvent-based dye-sub inks also is less then water-based formulations. However, the costs per square foot of the two inks are similar enough that cost isn’t a big factor.

Fabric also is a big part of the equation and is where conventional takes a leap ahead. The direct dye-sub process re-uires a coated fabric upon which the inks sit before heat transferring into the material. This coating always creates a stiffness that is not present in the uncoated fabric used in the conventional process. Dye sublimation requires fabric to have a high polyester content, and the availability of a wide range of uncoated polyester fabrics gives conventional the edge.

Fabric texture and other options also tend to favor conventional sublimation printing, and the cost of the uncoated fabric makes it the true winner. Media for direct dye sub can be two to five times the cost of a similar uncoated fabric, depending on availability and competition. Cost analysis seems obvious: Longer runs are best served with conventional dye sublimation when we strictly evaluate fabric prices, though the cost of transfer paper adds approximately 20 cents per square foot.

 

Ease of use

The direct sublimation method requires one person to operate a roll-to-roll printing system. Manufacturers of these systems tout the hands-free aspect of direct dye sub. However, the twist is that printing one job means additional jobs must wait. In conventional dye sub, the printed fabric goes to the transfer press, leaving the printer ready for the next job. Because the sublimation process occurs off press, the printer can start on the next job more quickly.

I also look at workflow management as a key issue around which to make your decision about which technology to add. The one-person operation and an all-in-one inline workflow of direct sublimation may be a better option for shops that don’t have the space or the manpower to support the multiple pieces of equipment associated with conventional dye sub.

Shop climate is another major consideration for conventional dye sublimation. Transfer papers are very sensitive to moisture, and a lot of trouble can ensue without a controlled environment. Changes in temperature and humidity can play havoc with high-release transfer papers, causing curling, dimensional changes, and other problems. Evaluation of daily and seasonal humidity, especially during summer and winter months, must be part of the quality-control process. The more humid the shop, the more saturated with moister the transfer media becomes. This moisture can lead to uneven transferring of the image and cause color shifts in the ink.

The direct-to-fabric process is less sensitive to trip-ups from the environmental factors that can hamstring the transfer workflow. However, if you make a mistake on the transfer paper, it’s a minor loss. If you make a mistake directly to a textile, it can be costly problem.

As the technology is today, the direct dye-sublimation method is perfect for the printer who likes to print and let it go, or the P-O-P printer who wants to diversify into fabric decorating. Fabric restrictions do create issues for the creative client, though the flexibility of this technology is wonderful. Conventional dye sublimation allows the utilization of a plant workflow to feed multiple machines. The methodology requires a bit more of a controlled environment, but it also allows for more media flexibility.

 

Opportunities

Dye-sublimation printing opens up a vast array of applications. Beyond P-O-P displays, you can make revenue streams out of upholstery, wall hangings, high-end decor, room dividers, artistic reproductions, educational or informative displays in schools and museums, all kinds of soft signage, banners, and more. Whichever approach to dye-sub printing you ultimately choose, you’re investing in a process that will allow you to explore new applications and markets. Who knows? Dye sub may even become the fabric of your business!

 

Rick Mandel is the owner and president of the Mandel Company in Milwaukee, WI. He also serves as CEO of the company's Screentech Division, a 115-year-old graphics firm that specializes in large-format color separations for commercial printing companies, as well as digital production of large-format graphics. Mandel is a member of the SGIA and the Association of Screen Printing Sciences. He holds a bachelor-of-science degree from the University of Wisconsin.

 

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