Learn about the equipment, materials, and processes used to produce digital transfers and how you can take advantage of this technology in your business
By Tom Frecska
How often does your company turn away customers because the number of pieces they want is lower than you can screen print at a reasonable price? How many potential orders have you lost because you don't decorate the types of products that your customers ask for? Whether you run a garment-printing operation, decorate ad specialties, or print signs, chances are that one or both of these situations occur on a regular basis.
The good news is that you don't have to let these opportunities slip through your fingers. Today, you can address short-run decorating needs and expand your product range without retooling your production floor or breaking the bank. All you need to do is add digital-transfer technology.
What are digital transfers?
Digital transfers are heat-transferable graphics that are generated on a computer and output with some form of digital-printing device onto a carrier medium (generally some form of transfer paper). After printing, the graphics are transferred from the carrier to the final substrate using a heat-transfer press in the same way that screen-printed plastisol transfers are applied to T-shirts. The transfer presses themselves are the same types used by screen printers, including both flat-platen models for garments and curved-platen versions for transferring images to mugs and other cylindrical items.
Digital transfers can be produced with a wide assortment of printers, including desktop inkjet, laser, and thermal-wax printers, as well as color copiers and wide-format thermal-wax and inkjet printers. What is the best system for your operation? That depends on the types of jobs you want to produce and the characteristics you expect from the transferred prints. Before you can make the right decisions in equipment selection, you need to be able to distinguish between the primary digital-transfer technologies and how they work.
Primary transfer types
If you're trying to sort out the various digital-transfer options, start with the materials that make the whole process work--the printable colorants employed by the systems. You have two general types to choose from: sublimation dyes and what we'll call surface colorants.
Sublimation dyes are available as inkjet inks, toners for laser printers, and ribbons for thermal-transfer printers. The term sublimation describes the process of changing a solid material directly into a gas without the normal liquid phase in between. Sublimation dyes are converted from solid to gas during the heat-transfer process and are absorbed into polyester and some acrylic materials, where they form durable, virtually permanent images.
The fact that sublimation dyes only react with polyesters tends to limit the types of products to which the transfers can be applied. For example, garments that are 100% cotton won't accept sublimation dyes, nor will non-porous surfaces that haven't been coated with a layer of polyester. You'll find out how manufacturers have worked around some of these limitations later in this article.
Sublimation dyes are transparent by nature, so they're only suited for use on white and light-colored objects. They are provided as process-color (CMYK) ink sets, regardless of the printer type for which they're designed.
Surface colorants make up the traditional inks, toners, and wax-ribbon systems used in inkjet printers, laser printers, and thermal-transfer printers. These materials comprise conventional pigments or dyes that don't penetrate the surface of the materials to which they are transferred as sublimation dyes do. Instead, these inks rely on polymer-coated carrier papers that release their coatings along with the image during the heat-transfer process. The transfer paper coating fuses to the substrate surface, effectively sandwiching the graphic between the substrate and the coating.
Transfer-printing technologies based on this form of colorant also generally involve inks, toners, and ribbons in CMYK sets. Some inkjet printers extend the set with additional shades to broaden color gamut, and thermal-transfer printers units frequently offer a palette of spot-color ribbons as well.
Specific transfer technologies
The way that sublimation dyes and conventional colorants are used to produce transfers varies with the equipment type and manufacturer. The most common approaches are described in the following sections.
Thermal-transfer printers Thermal-transfer devices use a heated printhead and pressure to deposit colored wax or sublimation inks from a ribbon onto the substrate. These units come in desktop varieties less than 18 in. wide, as well as wide-format versions up to 40 in. wide. Current manufacturers of these printers include Roland (www.rolanddga.com), Gerber Scientific Products (www.gspinc.com), and Matan (www.matan.co.il).
When thermal-wax ribbons are used to produce transfers, the graphics are typically applied to a coated carrier paper. As mentioned in the previous section, this coating transfers along with the graphics to the final substrate.
Thermal-wax transfers are best used on substrates like garments, where the wax and coating can penetrate fabric openings to grip the material and hold the image secure. On non-porous materials, the wax and coating can't form a strong bond with the surface, and transferred graphics can be scratched off the substrate.
If you use thermal-wax transfers on garments, keep in mind that the paper coating that accompanies the print tends to stiffen the garment surface, often giving it a heavier hand than a traditional screen print. Some customers may find this characteristic undesirable. Prints produced on thermal-wax systems also maintain a distinct dot pattern that reflects the output device's imaging resolution.
Most thermal-transfer printers support sublimation ribbons in addition to thermal-wax ribbons. In fact, when desktop printers were first introduced for producing transfers in the early 1990s, the most popular systems were based on thermal-transfer technology. Two types of thermal-sublimation systems emerged: one based on true or first-generation sublimation and the other on double or second-generation sublimation.
On true-sublimation systems, sublimation dyes are transferred along with a carrier (dry resin or wax) from the ribbon onto an uncoated transfer paper. The temperature at this stage is below what is needed to sublimate the dyes. Sublimation of the dyes occurs for the first time during the higher-temperature heat-transfer process, when they're applied to the final substrate.
With systems that rely on second-generation sublimation, the dyes are sublimated onto polyester-coated carrier paper. The prints are then sublimated a second time on the heat press, where they transfer into the polyester surface on the final substrate.
Because of the double sublimation process, transfer graphics generated with second-generation sublimation systems tend to provide less color vibrancy than the true-sublimation prints. However, with both systems, the dots of dye delivered by the printer become more diffuse as result of sublimation, giving the prints a nearly photographic, continuous tone appearance.
Inkjet printers Today, inkjet printers have become the most popular devices for producing heat transfers digitally. At the desktop level, units from Ep-son (www.epson.com) dominate the market (Figure 1), but wide-format models from Roland (Figure 2), Mimaki (www.mimakiusa.com), Mutoh (www.mutoh.com), and other manufacturers also support transfer printing. Print sizes range from letter and tabloid sizes on desktop models to widths up to 62 in. on wide-format printers.
Initially, inkjet transfers could only be produced using the standard inks that came with desktop inkjet printers. Just as with thermal-wax transfers, these transfers were produced on coated papers and relied on the coating to transfer with the graphic during heat application to the substrate. But eventually, companies such as Sawgrass Systems (www.sublimation.com), began offering sublimation inks for use in both desktop and wide-format inkjet printers, broadening the transfer-producing capabilities of these devices.
Inkjet sublimation transfers are printed directly on uncoated papers. The sublimation dyes are not activated during printing, but are carried in a water-based medium that binds them to the transfer paper. Activation of the dyes only occurs when images are heat-transferred to the final substrate. In other words, inkjet sublimation transfers represent a first-generation sublimation process.
Inkjet sublimation systems print more quickly than thermal-transfer devices. On average, inkjet systems can print full-color, letter-sized graphics at resolutions of 720 x 720 or 1440 x 1440 dpi in about 1-3 minutes. Desktop thermal-transfer systems, which typically have maximum resolution of around 300-400 dpi, take about twice as long to print a color image of the same size. This speed difference occurs because inkjets lay all four process colors down on the transfer paper simultaneously. On thermal printers, each of the process colors is laid down in an independent step of the imaging process.
Laser printers The last category of digital printers for producing heat transfers are laser printers (Figure 3). These devices have the advantage of being the fastest desktop option for printing transfers and can output 5-6 letter-sized, full-color transfers per minute at resolutions up to 1200 x 1200 dpi.
Conventional color laser printers use dry toners that are fused to a coated transfer paper. As with the transfers produced on other non-sublimation systems, regular laser-transfer images are heat applied along with the coating from the carrier sheet onto the substrate.
Just as with inkjet systems, sublimation materials are available for use on desktop laser printers. The most popular laser systems for producing sublimation transfers are models from Xanté (www.xante.com) and Minolta-QMS (www.qms.com). With these systems, special sublimation toners are applied to regular, uncoated bond papers. Images are sublimated from the carrier sheets directly to polyester and polyester-coated materials.
The laser-printer category is also home to a new transfer option that makes it possible to print 100%-cotton garments without using a polymer-coated transfer sheet. The new option is the Natura digital-apparel system offered by Sawgrass. This system combines a Xanté Colour ScreenWriter laser printer with specially formulated Natura toners. These toners are not based on traditional surface colorants or sublimation chemistry; instead, they employ a special heat-activated chemistry that reacts with cotton-fiber molecules to form a permanent image. The result is a soft and durable transferred graphic.
This is also a good place to mention that high-speed color copiers use imaging engines that are similar to those found in laser printers and can also be used to produce toner-based transfers on coated papers. However, copiers come with a substantial price tag and don't really compare with the more affordable printing options on which this article focuses.
What you can do with digital transfers
Now that you know how transfers are produced digitally, it's time to consider where you can apply them. If you use a system that relies on conventional surface colorants (regular inks, toner, or wax ribbons), you're restricted primarily to transferring graphics to light-colored garments. And again, this is only possible if you use the systems in conjunction with a polymer-coated transfer paper. Nevertheless, this option may be enough to satisfy those one-off and short-run custom garment orders you receive and lead to larger orders for your conventional printing equipment.
To gain access to the broadest range of imprintables, sublimation is the way to go. Companies such as Condé Systems (www.conde.com) and Xpres Corp. (www.xprescorp.com) provide complete turnkey solutions for producing sublimation transfers with packages that include digital printers, software, inks, transfer paper, heat-transfer presses, and a wide assortment of polyester or polyester-coated products to which sublimation images can be transferred. Among these coated sublimatable products, you'll find mouse pads, clock faces, coasters, plaques, signs, key hangers, name tags, picture frames, magnets, glass and ceramic drinkware (Figure 4), collectors plates, beverage insulators, ceramic tiles, and much more.
But you're not limited to only buying precoated items. Products such as Liquid Stone from Condé let you coat virtually any non-porous item so that it will accept sublimation graphics. The coating is a water-based liquid polymer that can be applied by paint brush, roller, or sponge.
On the fabric and wearables side, polyester T-shirts, sweatshirts, pillowcases, towels, and similar products can accept sublimation transfers without requiring a special coating. However, 100%-polyester garments aren't the most comfortable things to wear. Potential customers typically prefer that T-shirts be 100% cotton or cotton/poly blends.
Early in the days of digital sublimation transfers, the only way deliver cot-ton items with sublimated images was to print the sublimation inks onto a polyester-coated carrier sheet. With this approach, you transfer the image and coating to the garment together, just as you would if you were printing transfers with conventional digital inks. The only difference between sublimation and conventional images that are transferred along with paper coatings is that sublimation inks are absorbed into the coatings during the heat-transfer process, rather than just encapsulated by the coating and garment surface. But despite this difference, both methods still result in transferred graphics with a stiff, decal-like feel.
It took a garment mill to develop a solution that gives buyers of sublimation-decorated apparel the comfort of cotton without the stiff hand of a transfer-paper coating. Three years ago, Hanes Printables (www.hanesprintables.com) introduced Soft L'ink apparel, a line of T-shirts and other garments made from a patented, double-sided material (Figure 5). The fabric consists of a soft cotton inner layer and a 100% micro-polyester outer layer that supports sublimated graphics without a special coating.
The cost of investing in digital-transfer technology varies with the type of printer and ink system you buy. For complete desktop systems with all the equipment, inks, papers, and blank items you need to get started, you can expect to pay between $4000-8000. It's important to remember that the transfer process has been built around higher-end printers rather than home-office machines, so you can plan on paying $2000-6000 if you choose to source a printer separately. If you opt for a wide-format system, expect to pay at least five times more for the printer than you would for a desktop unit based on the same technology.
Consumables costs vary dramatically depending on the type and size of printer you're using and the type of ink system on which it relies. The most enlightening way to view these costs is to consider how they add up on a per item basis. For example, in T-shirt applications, your consumables would include ink, transfer paper, and the blank garments. Based on current supplier pricing, you could expect to pay approximately $3-5 for the materials used to produce one decorated garment. The good news is that will likely be able to sell the finished goods at a price of $15-20 apiece and enjoy a profit margin of 50-75%.
Cashing in with digital transfers
Developing new money-making opportunities for your screen-printing company doesn't mean that you have to focus on big-ticket technologies or expand your customer base. Chances are that your current clients already represent a great deal of untapped sales potential in the form of short-run and specialty printing needs. By adding digital-transfer technology, you can take on the kinds of jobs that you once had to turn away and quickly add to your company's bottom line.
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