January '23

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G R A P H I C S - P R O. C O M J A N U A R Y 2 0 2 3 • G R A P H I C S P R O 6 5 Challenges Many printing challenges can be over- come with time and practice, including polyester heat sensitivity, dye migration and ghosting. "Polyester fabrics are more sensitive to heat than cotton fabrics. Cotton prod- ucts tend to shrink after being washed and dried, whereas polyester products are prone to shrink and become damaged when subjected to extreme heat," Davis says. "To properly screen print on polyes- ter it is important to control and manage your heat during the curing process. Too much heat can damage a garment in sev- eral ways, including excessive shrinkage, dye migration, and scorching." Many inks on the market have been for- mulated to cure at temperatures between 280-330 degrees Fahrenheit. Exposing polyester products to temperatures higher than this can cause problems. "It's best to test and monitor the surface temperature of the garments being cured with a thermo-probe, as well as follow the print parameters set by the ink manufac- turer," Davis adds. Dye migration happens when the tem- perature needed to cure screen print- ing inks or apply heat transfers converts some of the dyes in the polyester into a gas. If this happens, the polyester dyes could mingle with the ink or transfer and change their original color. "To avoid this, it is highly recommended to use inks or transfers that are bleed resis- tant," Davis says. "Dye migration can be apparent almost instantly or could take several hours to manifest. It's advisable to wait 24 hours before shipping a finished product if you are unfamiliar with the gar- ment, inks or transfers." Ghosting occurs when shirts are stacked together while still warm. e image on one shirt can be transferred to the one stacked on top of it before it has had time to fully cure and cool down. Ghosting can also occur when prod- ucts are cured on a heat press without a cover sheet. Davis recommends applying a cover sheet between the printed image and the heat press before curing to protect the heat press platen from damage and keep the platen clean from ink that could accidently transfer from one garment to another during the curing process. Walker recommends that new shops don't bite off more than they can chew. "Be realistic. ere is a learning curve with any process. Don't expect to have a 1,000-shirt order before you get your equipment and then just be able to print that job," he says. "Ease into it, because the learning curve can cause you heart- burn when customers are expecting the product the next day and you have no experience in doing it. at is a recipe for disaster and disappointment." GP RTP Style 2000 Red polyester shirt with DTG printing. (Image courtesy RTP Apparel)

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