Advancements in digital print technology and the introduction of top coated fabric have allowed printers to expand their product offerings to include fabric banners. These technological advancements include: the ability of the machinery to feed and process heavier weight materials; improved compatibility of the inks with fabrics; and higher print quality.
As print head technology improved, digital printers could produce smaller ink droplets, which increased the number of dots per inch, resulting in crisper images. With the introduction of coated fabrics, inks could better saturate the fabric, so the colors are more robust and brilliant, instead of looking faded and washed out.
In the sign industry, top-coated banner fabrics for digital printing are relatively new. In the United States, use of these materials was initially limited. In contrast, the market in Europe and other parts of the world had more readily embraced the use of these materials. Some estimate that the worldwide market for these banner fabrics easily exceeds one billion dollars.
With digital printing you can provide your customers with the same print results as screen printing, without being locked into long production runs. The ability to print the one-of-a-kind banner or short production runs, gives sign shop owners the opportunity to provide the smaller retailer with high quality, customized graphics at reasonably low overall prices.
As the popularity of ecosolvent and solvent digital printers has grown, so has the demand for solvent-compatible banner media has increased. To meet these growing needs, manufacturers have introduced new banner media, which include vinyl banner material and banner fabrics.
The screen printing and dye sublimation processes do not require any special coating. Using high heat, dye sublimation prints can be fused to non-top coated polyester banner fabrics. Many uncoated vinyl banners can also be printed with solvent and mild solvent inkjet systems, if the right profile is used.
Printer manufacturers, such as Roland DGA Corporation (Irvine, CA), had developed custom-match material profiles for both topcoated and non-topcoated substrates. Roland offers a wide variety of profiled media for use with our mild-solvent and aqueous inkjet printers. The profiles which printer companies and material manufactures have developed take much of the guesswork out of achieving good color on those substrates. Custom media profiles are included with Roland’s VersaWorks RIP software so customers can take full advantage of the ability to balance excellent color with lower saturation levels.
While printing on many vinyl banners can be printed without a top coating, inkjet printing directly to nylon, polyester or cotton banner fabric, however, requires a special coating. As the digital market grew and printer technology progressed, banner manufacturer’s developed top-coated fabrics that were compatible with the inks. Top coatings have been formulated to work with a number of digital printers using water-based, solvent, ecosolvent and UV inkjet inks.
In selecting banner fabric, be sure to get a copy of the material specifications and study them carefully. Not all banner fabrics are top coated. Inkjet inks generally will not adhere to uncoated fabrics, which can only be decorated with screen print inks and, in the case of polyesters, dye sublimation.
The top coating on banner fabric serves a couple of different functions. First, it bonds the ink to the banner fabric. And second, it controls ink flow out. While it is important for the ink to penetrate the surface of the top coating, if the fabric absorbs too much of the ink the image could lose its intensity of color and appear washed out. It is critical for the top coating to maintain the integrity of the dot. A very porous surface will cause the ink to wick, which will lead to dot gain. When this happens, the finished appearance of the printed image will look distorted. On the other hand, if the top coating absorbs too little of the ink, the dot does not spread sufficiently and the image will look very grainy because there is too much space between the dots. Correct image reproduction requires a delicate balance of how the top coating controls the ink layer on the substrate.
The top coating can also contribute both to the useful life of the printed image as well as the durability of the fabric itself. Because the ink penetrates and embeds itself into the topcoat, the printed image becomes more abrasion resistant, which extends the longevity of the printed image. Some top coats for banner fabrics are also designed to make the fabric more flexible and add to the strength of the fabric, preventing fraying edges.
The range of top coated media options has expanded to include a variety of flexible media in part because the technology has changed. Wide format printers are more affordable and wider. These printers are designed specifically for printing on vinyl banners, fabrics and flexible signface material. And with the growth in sales of UV flatbed printers, printers can easily print on both coated and uncoated flexible substrates. In printing banner media, UV inks adhere well to a wide range of materials, but other advantage is nearly instantaneous curing time and excellent color saturation.
One of the major causes of print imperfections is contamination. Banner fabric is usually packaged on plastic, which protects the fabric from dirt and moisture. The best way to prevent contamination is to keep the media in its original package until you are ready to use it. Keeping the rolls sealed in the plastic wrapping will keep the top coating from absorbing moisture. Moisture in the top coating can cause a number of problems, such as dot gain, poorly defined and washed out images and poor ink adhesion.
Once you remove the media from its packaging, handle it with care. The oils of your skin can very easily contaminate the surface of a banner, which can affect the quality of the printed image. To prevent contamination, some people recommend wearing gloves when handling the material. Some manufacturers also recommend wiping down the banner fabric before printing. That may be easier said than done. Let’s face it, most printers are not going to unroll the banner material, wipe it down, reroll the material and then print on it. To expect a sign maker to do that is absurd.
When printing on top-coated materials, set the ink limits between 250% and 300%. The recommendation for ink saturation levels can vary from one material manufacturer to another. Ink limits vary by material and ink type. Printers have discovered that there are huge differences in ink limits depending on the ink type. Printing at recommended ink limits can also shorten drying times.
Heavy ink saturation can compromise the waterfast characteristics of the printed image. Heavy saturation of ink can also result in bleeding of the image if the graphic is exposed to water. Application of an overlaminate can protect the print, not only from water but also from dirt. Generally, if the printed image gets dirty, you will not be able to wash the surface without damaging the print.
After printing, you need to allow the inks to dry. Generally, you should lay printed banners flat and wait 24 hours before rolling the prints and shipping. Drying time, in part, depends on the temperature and humidity of your shop. The density of the ink print also affects drying.
As more and more sign shop are digitally printing vinyl banners, instead of applying vinyl graphics, the criteria for material selection has changed. If you are shopping for banner materials which are compatible with your printer, ask your distributor for samples, so you can do some test prints.
Before you select a banner for printing, you need to test it in your shop, in your printer and with your inks. Have your distributor provide you with a couple of yards to test and evaluate. One thing you want to check is how the material runs through your machine. Some of the inks need heat to adhere. That heat can deform the banner material. Experienced printing professionals also recommend monitoring and controlling your heat when printing on vinyl banners. When you turn up the heat, the banner softens up, which can buckle the banner and cause a head strike.
Because some inkjet top coatings can be damaged by excessive handling, handle them with care. Manufacturers typically recommend wearing cotton gloves and handling the material on the edges to prevent fingerprints and other damage.
Technological advances in digital printing, such as improvements in print resolution, printer speed, equipment cost and durability of the printed image, have spurred the interest and use of fabrics.
Drying times vary depending on several factors, such as the temperature and humidity in your shop, ink saturation, and type of ink.
Digital banner fabrics are specially top coated to accept solvent, eco-solvent and UV-curable inkjet inks. If you are buying a top coated banner fabric, make sure that the top coating is compatible with the ink in your printer. A top coating, designed for water based inkjet printers, may not work with your solvent-based printer. The quickest way to learn whether a top coated banner can be printed in your printer is to ask the manufacturer or your distributor.
Test, Don’t Guess
Sign makers should also test and evaluate a textile substrate before buying. The only test that really matters is the one that you do in your shop. Only after comparing printed samples can you make a confident buying decision. Not all fabrics are the same. Some print better than others. In selecting a fabric, compare how fast you can print the different products. Then, compare the quality of the printed images. If a fabric wicks the ink, you will lose the crispness of the printed image.
Testing the compatibility of your printer with a particular banner substrate is also a great way to get your feet wet in printing on fabrics. Many manufacturers provide sample rolls of material for test prints. After printing the samples, display the prints in your shop and solicit feedback from your customers. Printed samples are a great sales tool for starting a discussion about the benefits of digitally printed fabric and introducing customers to a medium that they may have been unaware of.
When using digital print technologies, such as dye-sublimation, top coatings are not needed. The dye sublimation process uses high heat to fuse a digitally printed image onto a substrate, such as a polyester banner fabric. In dye sublimation, graphics are printed in reverse using either an inkjet or laser printer onto a special transfer paper. The printed transfer paper is then placed on top of a polyester fabric or film or polymer coated substrate and then heated in a special heat press between 350°F and 400° F for about 30 seconds.
Because the dye becomes part of the fabric it cannot be abraded from the surface and banners can be washed again and again, without losing the vibrancy of its color. Dye sublimated banners are also less expensive and lighter weight than vinyl banners, and can be stored without wrinkling. By adding dye sublimation to their product offerings, sign makers have the opportunity to make high end interior banners for retailers. Printer manufacturers have developed a wide variety of equipment and inks which will satisfy the unique requirements for dye sublimation onto fabric.