Printwear

September '15

For the Business of Apparel Decorating

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2 0 1 5 S E P T E M B E R P R I N T W E A R || 97 Printing on a white 100 percent cotton shirt is easy. Spraying a pretreat solution on the garment is not necessary, although some believe pretreating a white shirt pro- vides a more brilliant color and is worth the extra expense and time. When printing on a black or colored shirt, and technically anytime you print white ink, you must always apply a pre- treat solution, and then cure that pretreat solution prior to printing. Consistency of the pretreat fluid ap- plication is absolutely critical. You must control all three axes: X (left to right), Y (up and down), and Z (the distance from the shirt to the spray nozzle), in addition to the amount of pretreat deposited on the garment. It is exceptionally difficult, if not impossible, to control these factors when spraying by hand. All mid- and high-volume direct-to-garment printing facilities use professionally designed auto- matic pre-treat spray devices. It is also crucial to weigh your deposit of pretreat fluid and document the num- ber for future reference. The amount of fluid will depend on the shirt you are printing on, the color of the garment, and your particular printing environment. A good starting point is 1.5 to 1.7 grams per inch, based on a width of 16". For example, if you are applying pretreat to a 16" wide by 20" long area, the amount of applied pretreat will be 30–34 grams, for a medium weight garment. The process of weighing the actual amount of pretreat solution applied to the shirt is easy. Set your gram scale on a level surface, put a bucket or box on top of the scale, and put the untreated shirt in the container. Tare the weight, spray the shirt, and re-weigh. The resulting weight is the amount of pretreat you have ap- plied to the garment. When using a heat press to dry-pretreat, do not use a Teflon sheet or silicone treat- ed parchment paper to protect the gar- ment. Instead, use a non-silicone treated parchment paper as a protective sheet. Do not clamp the heat press too tight. Simply lower the heat press to apply light pres- sure for 5–10 seconds at 330 degrees F. You will see moisture escape from the side of the heat platen. Then lift the transfer platen, quickly remove the pretreat cur- ing paper, and press again for an addition- al 15–20 seconds with heavy pressure. Overall cure time is around 30 seconds in two stages. If after 30 seconds there is still moisture trapped in the shirt,

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