Commentary & Analysis
Textile Printing 101
Digital textile printing is seemingly everywhere, and many sources tout it as a high growth area. New product announcements are also coming thick and fast. But what are the basics of digital textile printing? This week, we offer a basic primer on the topic.
By Richard Romano
Published: March 7, 2016
If you have been to an SGIA Expo or other major trade show—or are en route to this week’s FESPA Digital in Amsterdam—you know that textile printing is all the rage, and more and more traditional wide-format printing equipment manufacturers are introducing units that will print on fabrics. Soft signage has also been an oft-bruited printing application for the past couple of years and continues to grow. As a result, questions about textile printing abound, so this week’s feature will offer a general primer on textile printing.
What Can We Print?
First of all, what do we mean by “textile printing”? In general, we can identify three distinct categories:
Sign and display—This category would include banners and posters, trade show graphics, point-of-sale/point-of-purchase (POP/POS) displays, flags, outdoor graphics, and so on. This is also where we would classify “soft signage” in all its myriad forms.
Garment and apparel—This category includes anything that can be worn such as T-shirts, hoodies, caps/hats, uniforms and spiritwear (that is, sports or other team uniforms), swimwear, towels, bags (OK, bags aren’t worn, but can carry things you wear), and so on.
Décor—Think not just wall coverings, but also upholstery for chairs and sofas, as well as drapes and curtains, bed sheets, coverings for tables and other furniture, even carpeting.
As you can tell, these three categories include a bewildering variety of products (and, yes, there is some overlap of categories), not all of which can be produced on the same equipment. As in general commercial printing, and indeed in wide-format printing, different printing technologies are better suited to certain applications than others.
How Can We Print?
For decades—if not centuries—textile printing was done using analog printing of various kinds. One of the most conspicuous perhaps is screen printing, which emerged in the 1960s as perfect for T-shirts (such as concert tees) and other kinds of garments. At the high end, industrial textile presses are used for continuous sheets of fabric—that is, printed fabrics that come off press in rolls and are then cut and sewn into finished products.
As digital printing has grown and evolved, it has proven capable of handling many of these same textile substrates. When we talk about digital fabric printing today, we are largely—although not exclusively—talking about dye-sublimation. But this is not to exclude other ink technologies. Such as:
Solvent and ecosolvent—The same printers that can be used for traditional wide-format output can be used to print on fabrics, although it may not be the most desirable way of doing it. Solvent printing on fabric requires specially coated textiles in order for the ink to adhere properly. This may not make it suitable for items that will be worn, for example. Still, solvent inks are abrasion-resistant, fade-resistant, waterproof, and long-lasting and durable. Solvent inks are also inexpensive when compared to other inks.
Ultraviolet (UV)—You can also use a UV flatbed to print on fabrics. UV inks can be expensive compared to other inks, and since UV printing essentially lays down a thin polymer film, this can also result in stiff printed fabrics, again not entirely suitable if something is going to be worn, or at least worn comfortably. Still, UV printing is durable and lightfast, as you would expect, UV-cured materials are UV light-resistant.
Latex—Latex printers use water-based inks and can print on a wide variety of coated and uncoated substrates, including textiles. Indeed, latex printer vendors tout soft signage as an ideal application for this ink technology. Latex-printed materials are lightfast and solvent-resistant (so they can be dry-cleaned if necessary), but can produce muted, less-than-vibrant colors, and on some types of porous materials nay not be scratch-resistant.
If you have any of these types of wide-format printers, they can be versatile enough to handle textile printing, if that is an area that a shop wishes to expand into.
Before we look at dye-sublimation, it is worth mentioning that there is a class of textile printers called direct-to-garment printers (these are distinct from the dye-sublimation direct-to-fabric printers we’ll look at shortly). These use a special type of inkjet ink to print directly on pre-made garments such as T-shirts, hoodies, tote bags, hats, and the like. These devices are usually used for short-run printing of these garments, not high-volume industrial production. Unlike dye-sublimation, as we’ll see, these work best on cotton substrates. Three vendors have carved out a niche in this space: Anajet, which was recently acquired by Ricoh (the SPRINT and mPower i-series), Epson (the SureColor F2000), and Mutoh (ValueJet 405GT).
How Do We Print Using Dye-Sublimation?
Next week, we’ll take a deeper dive into the nuances of dye-sublimation, but here we can focus on the two broad classifications of dye-sub.
Transfer Printing—In this form of dye-sub, currently the most common form of digital dye-sublimation printing, the printer images on a paper that has a coating expressly designed to hold and then later on release (under heat and pressure) the printed image. After printing, the paper is brought into contact with the fabric in (or on) a heat press. The ink on the paper is then “gassed” directly onto the fibers of the substrate. This is the sublimation process where the solid colorant is converted into a gas to penetrate into the fabric. For chemical reasons, polyester fabrics are best-suited to transfer dye-sub printing. (That said, there are different kinds of dye-sub inks that can print on different kinds of natural and synthetic fibers.)
Some recent product introductions in the transfer dye-sub market are the 72-inch Durst Rhotex 180TR; the 44-inch Epson SureColor F6200, 64-inch SureColor F7200, and 64-inch SureColor F9200; the 77-inch Mimaki TS300P; and the 64-inch Roland Texart XT-640.
Direct-to Fabric—The next step for dye-sublimation is to take the transfer paper out of the process, for fairly obvious reasons: it’s an expense (about 10 cents a square foot for a decent quality transfer paper) and once transfer is complete it’s waste that needs to be disposed of. So a system that prints directly on the fabric is highly desirable. The problem, however, is that in order to do so, the fabric needs to be pretreated to accept the ink. Historically, pretreated fabrics were expensive and had inconsistent quality, but as dye-sub has taken off, substrate manufacturers have improved the consistency and quality of pretreatments. In direct-to-fabric printing, the ink penetrates further into the fabric than with heat transfer. The result can be less vibrant colors and softer text and images, as well as more show-through on the other side of the fabric. This is why the number one application for direct-to-fabric dye-sub at present is flags, where a high level of show-through is desired. (At present, duplexing with dye-sublimation is impractical, and for two-sided printing, you often need to print the second side on a separate piece of fabric and then sew or otherwise attach it to the first side.) That said, a lot of development is going into direct-to-fabric—both on the equipment/ink and the substrate side—and many of its limitations are starting to fall away. This is one area to keep close tabs on.
Durst’s new Alpha series industrial textile printers are virtually all direct-to-fabric (the aforementioned Rhotex 180TR transfer printer also has an optional kit that allows direct-to-fabric printing), while on the entry-level end of the market Mimaki has been demonstrating a prototype of its forthcoming TX300P direct-to-fabric printer. There will no doubt be further introductions and announcements at FESPA this week.
Anyway, next week, we’ll take a closer look at the dye-sublimation printing process.
How Do We Finish Printed Textiles?
Finishing for textile printing differs in many respects from other kinds of printing, even wide-format printing, but there are some common and some uncommon finishing processes.
Cutting—Cutting is the most basic finishing process in any kind of printing, and in the case of textile printing can involve simply cutting multiple impressions on a roll into individual panels (not unlike paper), to cutting the fabric according to a pattern in order to manufacture a garment.
Calendering—You may think that if you are using a direct-to-fabric system, you can avoid the heat press, but that’s not true. You still need a heat press or calender (despite Autocorrect’s insistence, “calender” is the correct spelling even though you can print textile-based calendars) to fix the ink onto the fabric to make it washproof and otherwise durable and long-lasting.
Sewing—If you’re manufacturing garments, the cut fabric needs to be sewn to form the garment itself. Even if you’re just printing soft signage, you still need some kind of sewing capabilities to hem the edges of the sign, to add pockets for support posts, or to otherwise handle the mounting and display hardware. Traditional sewing machines are often used for these processes, and there is still a fair amount of hand sewing done. Seamstresses are still very much in demand in the soft signage industry. How a banner or sign is going to be displayed or hung will largely define the finishing processes and skills required. Does it need to be stretched over a frame? If it’s an outdoor graphic, are things like post holes or pockets sewn strongly enough to withstand a strong wind? Do the hems of a sign get easily frayed? Will your customer’s nerves get even more frayed?
These are the basics of textile printing, and as you can imagine there are many many nuances depending on the application, the equipment, or even the individual job. Over the next few months, we’ll explore some of these, and next week we’ll take a closer look a dye-sublimation printing.