Printwear

June '15

For the Business of Apparel Decorating

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2 0 1 5 J U N E P R I N T W E A R || 73 a component rather than white pigment concentrate. This strategy creates an advan- tage to building opacity and color strength. Because high-opacity white doesn't count against the pigment load percentage, it creates room for increased additions of pig- ment into the mix. The percentages and ex- amples are shown above in Table 2. This mixing strategy especially works well on fluorescent colors. By increasing the per- centage of fluorescent pigments in the base, the color is more intense than the intended color, giving the color tech the ability to add additional finished white to the mix. The color then becomes more stable and opaque on the garment. SCREENS With water-based inks, the goal with mesh is to achieve the most open area possible while maintaining a clean image edge. Mesh counts between 110-230 t/in (43-91 t/cm) are recommended for vector designs to provide good ink deposit. Higher mesh, such as 230-305 t/in, could be used in half- tone printing if needed. Thread-count diameters, such as 45-48, also allows for more open area, which re- sults in better print quality, quicker color approval, and extended screen open time. A screen tension range of 25-35 n/cm2 ten- sion provides the best results. Screens must be prepared with water-resis- tant emulsion to prevent stencil breakdown on press. Some emulsions require a hard- ener to further prevent the printing process from degrading the stencil during extended production runs. Typically, a dual-cure, water-resistant emulsion provides a good stencil that won't break down and is still relatively easy to reclaim. A direct two-over- two coating helps create a good stencil on the screen. Stroke two coats of emulsion on the outside of the screen first, followed by two coats of emulsion on the inside. While coating the inside, apply pressure into the screen to force the emulsion to the outside of the screen. This technique results in the optimal emulsion over mesh of 15 percent to 20 percent. This is calculated by the overall emulsion thickness divided by the mesh thickness. The important aspect of this technique is that the emulsion is primar- ily on the outside of the screen. PRODUCTION In general, the best practice for water-based printing is the use of soft square squeegees. A good starting durometer range is a straight 60 durometer or a 60/90/60 durometer. Experience shows that the squeegee should be set at a 15- to 20-degree angle. Using minimal pressure on the squeegee with a double stroke provides excellent results. The optimal range of pressure is from 25 to 35 PSI. Visually, the first stroke won't clear the screen, but the second stroke will. This technique lays the ink on the surface while keeping the dot gain to a minimum. Set up the flood bar with at least a 1/32" space off the screen to create a heavy flood over the image. Have enough ink in the screen to have a complete flood over the image. To improve the screen life, a wing flood bar keeps the ink in the middle of the screen, aiding the flood deposit. The operator should set up the screen as if he or she were printing plastisol ink. A good off-contact to the shirt allows a nice peel-away from the garment. For better production numbers, set the flood and stroke to go as fast as possible while still clearing the screen, usually about two-and-a-half to three seconds. This keeps the ink wet and the flow consistent. Some water-based offerings rewet and flow well after a few strikes, allowing short breaks in production without putting the TABLE 2: COLOR FINISHED WHITE (Percentage by weight) Pantone 283 C . . . . . . . . . . . . . . . 20 — 25 percent Pantone 284 C . . . . . . . . . . . . . . . 15 — 20 percent Pantone 285 C . . . . . . . . . . . . . . . 10 — 15 percent Pantone 286 C . . . . . . . . . . . . . . . 5 — 10 percent Pantone 287 C . . . . . . . . . . . . . . . 2 — 5 percent Pantone 288 C . . . . . . . . . . . . . . . 0 — 2 percent Pantone 289 C . . . . . . . . . . . . . . . Not suggested DISPLAY ADVERTISING The Marketplace TO ADVERTISE CONTACT DIANE GILBERT AT 800-669-0424, EXT. 297 DGILBERT@NBM.COM

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