October '13

For the Business of Apparel Decorating

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Printwear 2013 Q&A Screen Printing Fun runs and competitive races present a huge market opportunity for decorators, provided they can decorate performance garments. (Image courtesy Hanes) What are non-woven poly bags and how do I print on them? Does a thicker, bleed-resistant ink film ensure against dye migration on a 100 percent polyester fabric? Non-woven fabrics are sheet or web structures bonded together by entangling fibers mechanically, thermally or chemically. They are flat, porous sheets made directly from separate fibers or from molten plastic or plastic film. Non-woven polypropylene is a practical fabric because it is strong and extremely lightweight. Most of these bags are made from recyclable plastic. This being said, they present a problem when they need to be screen printed. These new materials will not withstand the 325°F needed to cure plastisol inks. The best way to screen print these materials is to use a low cure additive in combination with plastisol ink to achieve a full cure at 275°F. By doing this, the ink will be cured without melting or distorting the material. Since there are so many different poly substrates in the market today, always test your print and material prior to production I have seen many printers attempt to deter potential dye migration through the use of excessive ink films. The truth here is that the thicker the ink film, the greater the required heat exposure that will be required to properly cure that excessive ink film. When printing on potentially bleeding synthetic fabrics, you will want to minimize the ink film thickness in order to minimize the heat required to properly cure the ink film. Most polyester fabrics will sublimate (and, in turn, migrate) when the fabric reaches 360°F. Some fabrics produced with cheaper dyes can even sublimate at lower temperatures. For this reason, utilize a good bleed-resistant polyester ink, tight screens, and print the thinnest ink film possible onto the surface of the fabric. This, in turn, will minimize the heat required to properly cure the ink film—though you'll still need to reach 320°F with most polyester ink films—while ensuring a proper cure and bleed resistance. John Levocz, International Coatings Rick Davis, Triangle Ink Company 86 | Printwear PW_OCT13.indd 86 October 2013 9/18/13 11:55 AM

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