Images Magazine Digital Edition July 2018

www.images-magazine.com TIPS & TECHNIQUES 26 images JULY 2018 Follow Marshall Atkinson’s expert advice and wave goodbye to dye migration, shrinkage and scorching on your tri-blend prints Terror-free tri-blend T-shirt prints T ri-blend. Have you noticed that this style is dominating T-shirt sales lately? The fabric, as the name suggests, comes in percentages of three sourced materials. Cotton and polyester usually make up the largest portion, but there can also be rayon or modal to make up the third. And, for the sustainability-minded, yarns can be recycled or organic too. But with that vast array of offerings from the shirt manufacturers comes a wide assortment of production challenges too. Tri-blend dye migration Dye migration is also called bleeding. The number one thing to understand is that this problem begins by overheating the polyester content of the shirt fabric. When the shirt was made, dyes were used to colour the polyester yarns to match whichever hue the manufacturer wanted for the garment. For tri- blends, these yarns are woven into the fabric with the cotton and the third material. If heated during your production process to the right temperature, the dye in the polyester content of the tri-blend fabric will change from a solid state to a gas and migrate up into the ink. Murphy’s Law dictates that this won’t happen while you are printing the shirts, but later, after the job has been boxed up and is on its way to a customer: when they open up the box, the white ink has taken on a pastel form of the shirt colour. And not in a pretty way. Any fabric with polyester content that has dyes susceptible to heat can produce unwanted dye migration characteristics. Red seems to be the worst actor in this scenario by far, but any dark dye can bleed into the ink when exposed to too much heat. How to prevent tri-blend dye migration The obvious answer is to control the heat during the process. Use ‘low bleed’ inks that are made to cure at a lower dryer temperature. Instead of the normal 160°C needed to cure the ink, low-bleed inks cure at about 135°C. But you shouldn’t stop there. There can be a cumulative effect on your production process with heat. A thicker ink deposit may take longer to flash cure than a thinner one. Compound this problem with a second flash during the production run, and then dog-piling the heat with the dryer chamber, and that jump-starts the problem. A better way to deal with this issue is to be smart about the design for the shirt, but also the mesh counts used for the screens. Design your graphic to use fewer large areas of lighter colours if you can. As lighter ink colours are more prone to showing the dye migration gas when overheated, using The right hand side of the chest print [above] shows the effects of dye migration on white ink; the ink has taken on a tint of the base fabric colour These shirts have an instant vintage look and feel, like a hug from an old friend T R I - B