New Techniques in Special-Effects Screen Printing
Special effects give garments unparalleled visual and tactile appeal. This article showcases effective methods for boosting the value of printed apparel.
At first glance, it may seem as if the garment marketplace is running low on truly new special-effects prints. However, inks, fabrics, and printing processes are changing in response to consumer trends. For example, customer requirements for PVC-free inks and increased use of polyester fabrics are affecting garment screen-printing significantly and will continue to do so for the foreseeable future.
Demand for special-effects printing is coming back right now, and most major brands have at least some graphics in each season’s lines that use one specialty technique or another. What is different is that most special-effect printing is entirely design driven rather than just technique for its own sake. The technique is secondary to a quality graphic and adds to the design rather than being just used for effect or to lend pop to a weak design. The gallery of effects shown in the images above highlights modern trends and methods and presents an overview of the techniques and consumables used.
Heat sealing with transfer paper A very smooth halftone blend was printed on top of a specially smoothed underprint and then heat-sealed using a glossy transfer paper. This really evened out the surface of the print and imparted a subtle shine to it, much the same way a clear foil might. The effect added to the design, whereas a rainbow or metallic foil might have overpowered it. In this case, what some refer to as a smoothing screen was used on press to impart surface finish. This is a screen with a high mesh count—but without an image exposed on it—that’s printed, so to speak, with a hard squeegee after a flash in the print sequence. Squeegee actions smooth the gelled ink slightly while the garment is still on the press.
Heat transfer on specialty ink A typical puff ink was used as an underprint, and a halftone blend was then printed on top of the puff after flashing. The fabric in this example had a high polyester content, so a low-bleed white ink was printed under the puff to prevent dye migration. The finished design was then lightly heat-sealed with a dull transfer paper for just a few seconds to smooth the top surface of the print slightly. This effect is much different from a solid area of highly lofted puff. This technique adds some luster and depth to the graphic without being overly simplistic and gives it a different look.
Simulated embroidery Puff was used as an underprint, but in this case as a small portion of a much larger design to simulate embroidery on top of a print. It kept the shirt much softer than authentic embroidery could. This fairly subtle treatment didn’t overpower the graphic. This technique was not used for the novelty of the effect, but rather because it worked well with the particular graphic and reduced the cost of production compared to embroidery.
Printing for hand You can produce soft-hand and no-hand prints in any number of ways, but consider the possibilities of using soft-hand prints as parts of larger designs or as background color components of more complex special-effect prints. A design can use many different levels of hand in the same print for different effects. In this photo, water-based inks of varying viscosity were used to produce an accurate representation of the details of a sketched illustration. Heavy-bodied ink was used where multiple layers of cross hatching overlap and in the richer colors of the illustration. Much thinner, water-based inks were used where the line work and shading in the design fade into the garment. The varying levels of hand in the print contribute to the rich look of the design. The water-based inks used in the graphic lend themselves to soft-hand printing extremely well.
Water-based effects Distressed techniques and washed simulations are popular special-effects variations of soft-hand printing. In this photo, extremely soft, water-based ink was used to simulate a heavily washed and worn print. Screens with high mesh counts, very thin ink, and very hard squeegees were used to limit the total amount of ink laid down on the garment.
Discharge printing Discharge formulations facilitate the production of distressed graphics on dark fabrics. Dye migration makes soft-hand techniques with thin inks a challenge on polyester and polyester-cotton blends. No very soft-hand inks can prevent dye migration with any reliability. Discharge fluids are not commonly used on polyester fabrics because the solutions do not remove the dye very well from the polyester fabric. This limitation is an additional challenge to any type of very soft-hand printing on some of the fabrics popular right now.
Dye-interactive inks Some inks are formulated to resist the dyeing process; others are designed to attract additional dye to the areas on which they are printed. You can use these water-based inks to satisfy customer requirements for PVC-free product. In these photos, two strengths of dye-resist inks and two strengths of dye-gain inks were printed in halftones using screens with high mesh counts. A soft-hand, almost distressed print becomes visible after the dyeing process.
PVC-free plastisols These prints were made with some of the newer PVC-free plastisols currently making their way into the marketplace. These inks are a response from the major ink manufacturers to customer demand for inks that do not contain polyvinylchloride or phthalates. Additionally, the inability of water-based inks to provide everything needed by every printer has helped lead to the development of these new acrylic alternatives. These inks, depending on how they are used, print much like standard plastisol ink with a few minor production limitations. Few alternatives are available that prevent dye migration on polyester fabrics, though solutions are in development and testing.
Printing with silicone Silicone inks are among the newest products on the market. They’re designed to meet customer demand for PVC-free ink and are in testing and development for a number of different uses. Some production difficulties exist, especially with regard to high-speed, automatic production. However, the ability of silicone inks to impart a very desirable look keeps the pace of product development high. These inks also represent some very attractive performance characteristics, especially on polyester and performance fabrics. Dye-migration resistance and elongation are excellent. In this example, silicone inks were printed through coarse screens with thick stencils. The semitransparent inks used in the print give the graphic a look and feel similar to traditional gel ink.
High-solids inks Some high-solids or opaque water-based inks can work well on some polyester and most polyester/cotton blends. The potential for dye migration is minimized because these inks do not contain a true plasticizer and because the dryer temperatures can usually be a little lower than what would be required for a standard plastisol. However, you must test on a case-by-case basis before proceeding with production quantities. The graphic pictured here was printed with a high-quality, high-solids, water-based ink on a polyester T-shirt. The inks prevented dye migration issues on this particular fabric quite well, and the print’s quality and integrity have held up over time.
Discharging on blends Surprisingly, discharge fluids will occasionally work on polyester/cotton blends. These formulations can yield very unpredictable results, but they are proven in production in a noteworthy number of instances. Discharge fluids are not recommended for this specific use, so you’ll need to test carefully. This example shows an opaque or highly pigmented white discharge water-based ink printed on a 60/40 polyester/cotton fabric. It was flashed and then printed a second time. The discharge removed enough of the dye in the cotton portion of the fabric that the white pigment in the ink was able to block the remaining dye in the polyester portion of the fabric.
PVC-free HD You can make these PVC-free inks into high-density inks without much difficulty. These examples show multiple layers of PVC-free, high-density inks printed through coarse mesh (250-micron stencil thickness).
High-density designs Polyester and polyester/cotton blends bring many new challenges to any specialty garment print. The dyes in the fabric can migrate through the printed ink, thereby changing the color of the ink. Dye migration can take place—or worsen—over time. The cure temperatures of most inks also contribute to the effect because dye migration is often a heat-related issue. High-density inks can help prevent dye migration on some fabrics because of their high solids content and thick ink film. In this example, a high-density ink was printed in multiple layers on a 60/40 polyester/cotton blend through coarse screens coated with thick stencils. If you’re in doubt about dye migration, then consider using a low-bleed underprint. Also note that you must configure your dryer to cure the high-density ink formulation completely.
Semi-gloss style In this example, two layers of a clear, thickened, PVC-free plastisol were printed over a standard, PVC-free graphic to simulate a thick, semi-gloss patch. Low mesh counts and thick stencils were used for both clear screens.
If you’re looking to cash in on the renewed interest in special-effects printing, keep in mind that customer demands for PVC-free inks and the increasing prevalence of polyester fabrics can limit the possibilities. New inks designed to meet these requirements also place the burden on printers to test and document their results and adjust to the corresponding changes in techniques and fabrics. As with any new challenge, this can make for an exciting opportunity to come up with innovative, new solutions, new printing methods, and product development.
Michael Beckman is president of MB Screen Printing Inc., which has been providing a variety of technical services, seminars, workshops, and speaking engagements for the textile printing industry for many years. Michael is responsible for the de-sign and development of many new screen-printing products and techniques. MB Screen Printing Inc. has recently been involved in a number of long-term projects establishing and managing factories throughout the world. He can be contacted at firstname.lastname@example.org