Images Magazine Digital Edition July 2018

www.images-magazine.com JULY 2018 images 27 TIPS & TECHNIQUES darker ink colours helps to camouflage this challenge from the start. Higher mesh counts with quality, high-tension screens will transfer less ink onto the surface of the shirt. This will reduce the flash dwell times needed to gel the ink. Watch your flash dwell times Also, while we’re on the topic of flash dwell times, many shops think that the flash unit has to completely cure the ink before the shirt can receive the next ink colour in the print rotation. This is untrue. All you need is for the ink to gel and no longer be wet. The dryer will completely cure the ink: the flash unit is designed to keep the already printed ink from smearing during the production process. Over flash-curing is one of the top reasons for dye migration in polyester shirts. After the just-printed ink is carefully flashed, be sure to then have a cool- down station to give the heated ink a moment to drop in temperature before you add another colour. Don’t forget about your platens During a longer production run, the platens on the press can become superheated too. This happens because each time a shirt is printed, the board receives heat from your flash unit. Over time, the platens retain much of that heat. If the flash unit dwell times are not adjusted to a shorter duration, the residual heat on the boards can affect the print and produce unwanted tri-blend dye migration. Press catcher best practices The best person on your press crew besides the press operator to control the heat challenges during production is your catcher. Normally a catcher will grab shirts and start stacking into dozens so they can be folded and placed into a box. Instead of one stack of shirts, try creating four on the table. As the shirts travel down the belt towards the catcher, each subsequent shirt is placed into the next stack of shirts in the row. A fan can be used to blow air onto the shirts to cool them down, and they should not be boxed up until they are cool to the touch otherwise the ink will continue to cook. Key tips for mitigating tri-blend dye migration Start with employee training. Discuss the cause and effect of what happens in production with all of your staff. Avoid art that requires an underbase white if you can, because every flash impacts the outcome. Engineering your print from the art standpoint is the best cure. Since tri-blend T-shirts are known for their softness, you want to emulate that with the print. Building up multiple layers of thick ink will feel at odds with the softness of the fabric. A better strategy is to use water-based ink or plastisol with some curable reducer added for an extra soft print. Minimise the ink deposit by using higher tensioned screen frames with higher mesh counts. Use a sharp squeegee with minimal pressure. Your goal is to have the ink kiss the top of the fabric and stay there, so you want just enough pressure to clear the ink from the screen. Adjust your flash unit dwell times during the print run as the press platens heat up. The dwell times should decrease as the order continues to be printed. Tri-blend discoloration On some tri-blend shirts, the excessive heat build-up causes the hue of the shirt to darken or brown. Again, this is a dye- related issue caused by heat. The best practice is to control the heat and be careful to not use super-heated platens with long dwell times with the flash. Tri-blend fabric compression and shrinkage One common challenge with using a tri- blend blank is that sometimes the shirt will shrink on the press when exposed to heat. The underbase printed fine, but after flashing the shirt shrinks by a small amount, just enough so that the other screens are not in alignment. While many printers run the entire order through the dryer to preheat the shirts with the idea that this will prevent on-