TEXTILES.ORG
Explore the two printing technologies that have taken the fabric graphics industry by storm.
By Maura Keller
In this day and age, our media-saturated environment is teeming with bigger, brighter and longer-lasting images. From theatrical backdrops to grand format advertising banners to tradeshow booths, many of today’s vibrant printed images are the result of dye sublimation transfer and direct dye sublimation—two technologies that have taken the fabric graphics industry by storm.
Status of dye sublimation
At its core, dye sublimation uses a heat-generated printing process in which heat is used to transfer dye onto paper or fabric. The dye is transferred from a solid to a gas onto the intended medium. The dyes used are intended to bond most effectively with polymers, so the higher the polyester content in the substrates used, the more the dye will bond to the material. The result? A crisp, well-defined and brighter image that keeps consumers coming back for more.
Bart Read, vice president at Moss Inc. in Belfast, Maine, explains that dye sublimation requires a heat cycle to set the image onto the fabric.“Uncoated polyesterfabrics are processed with a transfer print from a printed paper print to the fabric through a calendar or heat press,” he says. “The image goes from a solid to a gas and is deposited into the fabric so it is colorfast and can be washed. Coated polyester fabrics can be printed directly to the fabric and then heated to set the dyes into the fabric.Ultraviolet (UV) and solvent printing can be applied directly to the substrate and require no post processing, as the UV lighting for UV printing is built into the machine.”
Since its inception more than a decade ago, “dye sublimation is becoming increasingly popular in the United States thanks to its existing popularity in Canada and Europe,” says Steve Gazdag, president of KSK Visual Ingenuity, a Cleveland, Ohio-based company that offers a variety of imaging options, including digital photo and backlit, color solvent, direct UV, dye sub and inkjet technologies.
Dye sublimation printing can be used for making sports uniforms, soft signage and even gaming table covers. Steve Urmano, marketing director at Mimaki USA explains that there are three primary types of inks used to produce sublimation graphics: water, solvent and oil-based. “Water-based sublimation inks that are using disperse dyes produce good color with relatively high resistance to ultraviolet,” he says. “Direct sublimation printing with these inks calls for a two-step workflow of printing and heating either using a heat press or inline. Water-based inks that are used for sublimation transfer printing require heat-transferring the images to the final substrate. This method tends to result in graphics with sharper detail than direct printing.”
According to Urmano, the transfer method with water-based inks has one major drawback: The media can be saturated, which can cause cockling of the material and can distort the transferred image.
Solvent media being used primarily for soft signs have become available relatively recently. “A major drawback of solvent media is that they can’t be used against the skin in any garment application,” Urmano says. “Some printers that use solvent-based inks for sublimation transfer may be equipped with tensioning systems designed to keep the media very tight. These can be added as external devices to mid-range solvent printers being used with aqueous dye-sub inks.”
LED UV and even high-energy-cured UV inks can be used with some textile media for soft signage applications. “One problem can be a clotting of the ink or even an undesirable ‘hand,’” Urmano says. “This textile printing area is fairly new, and I suspect it will take some time for this area to be perfected.”
So what types of substrates are typically used within the dye sublimation process? “Fabric and only fabric,” Gazdag says. “KSK works with several different types of fabric based on the project. Fabric architecture almost always calls for stretch fabric or a knit blend with block-out liners. The walls we produce require a heavy knit, while the theatrical projects prefer scrim, a mesh that works with lighting to achieve a specific effect on stage.”
In addition to sport applications, dye sublimation has become the preferred product for trade shows because of the color pop, durability and hand. “It is also getting used in high-end retail and interior signage,” Read says. “It does not have the UV durability required for long-term outdoor use, so it does not compete with UV or solvent for permanent outdoor projects.”
The typical equipment used with the dye sublimation process is either modified or specially configured wide-format printers with auto media feeders and “sticky belts” for imaging disperse inks on spandex material for swimwear and sportswear applications.
“Some equipment has integrated heater systems for inline sublimation, while others require an outboard calendar type heat transfer device,” Urmano says. “Typical wide-format printer widths are 60 inches, although Mimaki will soon offer a direct to print in a 126-inch width. By far the 60-inch size is the best selling.”
Transfer or direct
There are two distinct methods of printing within the dye sublimation process: transfer and direct. The transfer method sublimation process involves printing an image on a special media that usually is a special dye sublimation paper with a receptive coating that holds the ink. “There are now plastic-based media for use in thermoforming applications,” Urmano says. “The ink is typically a resin base that holds the ink pigment so when heat and pressure is applied, the ink will transfer to a receptive surface of a polyester-based material.”
The direct sublimation method actually deposits the ink onto the media itself, and then it’s fixed into the media using heat and pressure. “Although this method in the past did not have as good a saturated image result, it has become much better as media surface coatings have been vastly improved,” Urmano says. “Now you can buy dye sublimation media that are pretreated on one side for direct sublimation, or non-treated on the other for use with transfer paper.”
Experts also note that direct dye sublimation printing to coated fabrics has eliminated the need for transfer paper and heat transfer machinery, making the costs to produce lower. “The quality of direct print is getting to be quite good, although the fabric choices for the best print are limited to flat, smooth surfaced fabrics,” Read says. “Direct printing saves the paper transfer, and because most of the direct machines I have seen have a heating unit built into them, it also saves the time associated with transfer and eliminates the need for a separate transfer press.”
As Read points out, there are many quality issues related to the transfer process that are all eliminated with the direct dye sublimation process. “Direct printing works well with smoother substrates but the quality is not as good as paper transfer onto knit materials, for example,” he says. “Direct also requires a coated fabric, which adds some minimal cost per square foot to the cost of the fabric. The transfer method has higher costs for materials and labor, but better print quality.”
Direct dye sublimation has been primarily used for soft sign and flag applications. “Flag material typically has a looser weave that needs to accept enough ink to image through both sides adequately,” Urmano says. “To do this, the machine usually has a ‘ditch’ installed that will allow the excess ink runoff to be captured so that the ink will not contaminate other image areas.”
Other substrates used include polyester-based media, which come in a wide range of weave densities, as well as polysatin, gaming felt and flag mesh. Specially coated polyester-based receptive materials for decorating buttons, belt buckles and personal electronics cases are also types of substrates used in the process.
“For the industry’s big players, dye sublimation transfer makes up the majority of the fabric printing market,” says Jason Bartusick with Media One USA. “Dye sublimation transfer has a big market, yet not a lot of players have gotten into direct dye sublimation.”
The reason?
Direct dye sublimation technology is relatively new, whereas dye sublimation transfer has been around for about 10 years. “The width of the printers is also an issue because, up until the recent Jeti AquaJet printer, direct dye sublimation hasn’t had large enough printers that many shops require,” Bartusick says. “For dye sublimation transfer, there is a lot more equipment available and it is a lot easier to print to paper than printing directly to fabric, because when printing directly to fabric you need to have tension. However, our industry has always gone for faster printers, better quality and with less labor. Direct-to-fabric printing has a lot less labor costs.”
Best method selection
So what’s the best dye sublimation method to use in your shop? That depends on whom you ask and the type of requests you have from your customer base.
“The best way a for a print shop to determine which dye sublimation printing method to use is to determine the type and quality of output required,” Urmano says.
For instance, if the work is printing sports jerseys, then paper will give you the most saturated color and crisp line detail. “At least for now, paper transfers have the edge in that area,” Urmano says. “If the applications are POP, stage backdrops, mesh and flag, then the fastest printing and fixing methods take precedence.”
According to Craig Furst at AAA Flag & Banner, his company has chosen a direct print method because it feels there is greater productivity with less waste.
“Paper transfer has higher resolution, and greater detail is achievable with less dot gain,” Furst says. “Customers don’t know or care which method is used. They may have a quality standard that must be met and that may dictate the best approach. Paper yields higher quality and direct yields higher productivity.”
Gazdag agrees. “A successful shop determines its clients’ needs and offers the right solutions to meet the demands,” he says. “They also take the time to really learn the technology, inks and materials. Many shops who want to offer the dye-sub option will form wholesale partnerships with companies such as KSK so they can avoid the equipment costs and overhead, while still meeting the demand of their customer.”
Print shops need to determine the typical viewing distance of their prints and the materials they use to determine which system to go with. “Close-up viewing with high-resolution requirements on knit fabrics would lead to paper transfer,” Read says. “Smooth fabric surface with less resolution required would point to the direct method. You might want each system in your shop to be able to supply the right print for every use.”