Dye sublimation is the next big surge in the digital textile printing industry. Quick to take off in Europe, dye sub is becoming the choice technique for end-users because of the efficiencies in fabric shipping and handling, as well as the rich, high-quality results. Fabric is beautiful, but printing on it can be challenging.
With this issue, we are launching a five-part series that will explore the intricacies of dye sublimation with guest expert Michael Syverson, Director of Special Projects at Louisville, Colo.-based PrinterEvolution. Syverson has more than 20 years in the printing industry and was an applications specialist on the VUTEk project team when it unveiled the first dye sub printer in 2001. Let’s begin with an overview of the dye sublimation process from inks to equipment, but in subsequent articles we will further examine such topics as substrates, inks, heat setters, finishing, marketplace economics and workflow. Although there are many different approaches and variants to sublimated fabric printing, we will focus primarily on transfer dye sublimation because that is more widely used in the U.S. grand-format arena. We asked Mike the following questions:
There are really three types of printers: all-in-one units with a built-in fixation heat press; printers that just print either transfer or direct; or in some cases, both.
Q. What is dye sublimation?
A. Dye sublimation is the process of converting solid dyes into a gas without going through the liquid stage. Heat and pressure are used to infuse colorant into a polymer material (usually polyester). There are two basic methods for printing with dye sublimation inks, direct and transfer. Transfer is the most common method in the U.S. and consists of printing an image on a transfer paper and sublimating the image onto a polyester-based product, usually a textile. The direct process differs from transfer printing in that the image is printed directly on a coated fabric and then sublimated without the use of paper.
Q. What are the advantages and disadvantages of the direct and transfer processes?
A. Both methods require heating the fabric in order to infuse the ink into the fabric, but both have their pros and cons. Transfer printing allows the most flexibility in terms of substrate range. You can basically sublimate to any polyester textile (or other polyester coated product for that matter). Transfer printing is very efficient, as you only need to profile and set up the printer for the one transfer paper you are using. Setting changes for the different fabrics are made at the heat press calendar. And printing on paper means you don’t have to worry about the fabric moving, stretching or wicking thereby giving you a clearer, more perfected image with sharper color “pop.”
Direct print has been around for several years and many pieces of equipment have been designed specifically for this application. An advantage of this is you can eliminate the need for transfer paper altogether, which can simplify the process in some ways. Direct printing also increases strike-through, making the image apparent on both sides of the fabric. In some applications this may be desirable.
Aqueous dye sub printers, such as this Evo33 from PrinterEvolution, are in demand because of the green benefits of using water-based inks over oil-based or solvent-based inks.
On the downside, you need to characterize the printer for each fabric (separate ink limits, profiles, etc.) Additionally, you need coated fabrics to provide the best possible output for direct print. This can add cost, sometimes mitigating the cost of transfer paper. Also, there isn’t as wide an array of direct-coated fabrics available as uncoated fabrics. Finally, in many cases the output from direct print is not as sharp as a transfer printed piece. The best print equipment offers both, giving you the ability to produce graphics with either the direct or transfer method depending on the client need.
Q. What are the different dye sublimation inks and coatings?
A. There are three popular variants of dye sub ink: solvent-based ink, oil-based ink and water-based ink. The transfer applications for each of these ink types are roughly the same, using coated transfer paper to release the ink effectively. The main difference with these inks is the medium in which they are carried.
Water-based ink is the most common formulation of ink for dye sublimation and by far the most eco-friendly. With green printing growing in popularity, water-based ink offers outstanding attributes. Printers that print with water-based ink range from in-home consumer converted printers to grand-format industrial inkjet printers. Solvent-based and oil-based units are primarily seen in the grand-format space.
Customers in the soft signage, trade show, retail, P.O.P., event and entertainment industries are really enjoying the benefits of dye sublimation textile printing and a huge opportunity exists in these areas from small to large sign shops.
Historically, oil-based and solvent-based inks were used because of difficulties with water-based inks, availability of water-based compatible print heads and a compatible transfer paper. As paper gets wider (10 feet or 3 meters) it can become unstable during print, in terms of wrinkles (or cockles), which can cause print artifacts or head strikes. Additionally, when the first grand-format dye sublimation printers were designed, there were not many print head choices that were able to run water-based inks. Responding to demand, paper manufacturers have created papers that run smoothly through a printer, even with high ink loads at industrial level print speeds. Also, there are many more print head choices that are aqueous compatible.
Coatings vary depending on the manufacturer and ink. Different papers all have their own characteristics to hold and release inks. Clay coated paper seems to work best with water-based inks.
Q. Who uses dye sublimation and what are its applications?
A. Customers in the soft signage, trade show, retail, P.O.P., event and entertainment industries are really enjoying the benefits of this type of textile printing and a huge opportunity exists in these areas from small to large sign shops. Typical applications include banners, stretch graphics for exhibitions, flags, T-shirts, retail point of purchase, tents, even hot air balloons. Also, imprintable items such as coated ceramics, wood and metals use this method, but it is important to note that dye sub is designed only for polyester based materials. In the case of solid substrates, like a coffee mug for example, the mug must have a polyester coating, usually a liquid that is baked on. If the substrate does not have a polyester coating, then the process will not work. Natural fabrics such as cotton and silk require different processes, such as an acid or reactive ink.
Dye sublimation allows for a wide variety of substrates, including silk. (Photo courtesy Mimaki)
Q. Why use dye sublimation as opposed to other printing methods?
A. Overall, dye sub’s advantage over UV-curable, latex or solvent printing is the ability for the fabric to have the same feel, or “hand,” which adds to the high-end perception of the product. Put simply, the end result is by far better in look and feel because the ink is infused into the fibers of the substrate itself, as opposed to a pigmented ink that builds up on the fabric. This level of saturation produces superior output. Another important benefit of the ink being infused directly into the fabric is that without any additional surface protection, the image is now permanent and cannot be washed away, rubbed off or otherwise removed from the fabric.
UV, however, is the most versatile of these other ink technologies. It adheres well to a wide variety of substrates, including fabric, but it does change the feel of the material. Latex is similar to UV except that it can produce better, brighter color on textile than most UV printers. It can change the hand of the material, but not to the extent that UV does. However, a latex printer must be slowed down and print many more passes to achieve the same color as a dye sublimation print. Solvent inks (pigmented inks not to be confused with solvent-based dye sublimation ink) require the material to be coated with a receptive layer for the solvent ink. This can change the hand of the material as well. In addition, solvent output generally produces a less saturated image than the same print with dye sublimation.
Q. If someone wanted to get started in dye sublimation, what equipment would be required?
A. Basically you need a printer, some sort of heat press to sublimate the ink and some finishing equipment. In the U.S. you will find about six manufacturers offering printers. There are really three types of printers: all-in-one units with a built-in fixation heat press; printers that just print either transfer or direct; or in some cases, both. The all-in-one units are designed for direct print only. Some of the separate printer/press units are transfer only and some separate printer/press units can produce graphics with either the transfer or direct method, depending on application and the type of output required. Then there are a variety of fixation units, from small clamshell heat presses where pressure is applied manually (think T-shirt shop), to industrial sublimation calendars for roll-to-roll grand-format machines. Lastly, there is the finishing equipment such as sewing machines. We are going to get into this in more depth in the future, but basically those are the three big components.
Some of the reasons dye sublimation is a growing market is because of the efficiencies in fabric shipping and handling, as well as the rich, high-quality results. (Photo courtesy Fisher Textiles) (Right) Inks for dye sublimation can be water-based, oil-based or solvent based. (Photo courtesy Sawgrass)
Q. Why do you think adoption of this process has been slower in the U.S. than in Europe? What are the barriers to trial?
A. In my opinion there are two reasons: First, the perceived high cost of entry and steep learning curve because of the complexity of the process. Secondly, finishing. On the first point, equipment and materials are expensive but the margins are much higher. Because of the complexity of producing dye-sublimated graphics and the cost of the materials themselves, the selling price of fabric per square foot can range from $7-$10, which is greater than vinyl by a dollar or two. In other words, printing businesses stand to make a lot of money and the dye sub market remains on a healthy upswing. It is less competitive than say banner printing, which has become somewhat commoditized. In the long run, transportation, handling and overall management of fabric is less costly as well, which is attractive to end-users. On the second point, finishing takes people out of their comfort zone. There is a general lack of education in our industry about sewing, appropriate setups for sewing equipment, supplies like needles, threads and the various types of sewing machines. This has left many in our industry apprehensive about taking the first step into the dye sublimation business. However, the market is wide open with great opportunity for print shops to increase their margins, differentiate themselves, and remain competitive.
The end result of dye sublimation is a high-quality look and feel because the ink is infused into the fibers of the substrate itself, as opposed to a pigmented ink that builds up on the fabric. (Photo courtesy Tex Visions)
For Part 2 of this series, Click Here.