Do you know what is one of the worst feelings? The dread that fills your soul when a printed poly shirt comes out the end of the dryer and you notice the shirt’s dyes seeped into the print. (Don’t even get me started on printing white ink on a red polyester shirt.) It’s a screen printer’s nightmare. To keep the bad dreams away, learn how to prevent dye migration from happening in the first place.
WHAT IS DYE MIGRATION & WHY DOES IT HAPPEN
Dye migration is when the dyes in the garment discolor the ink of a print. Why does it happen? Science. Basically, most dyes in polyester fabrics are set at 270°F-300°F. When the threads hit that temperature, the dyes become gas and the ink absorbs it, which discolors the print. You’re probably wondering, “Plastisol inks cure at those temps, even higher than that. How in the world do I screen print on polyester?” Luckily, you can prevent it.
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HOW TO PREVENT DYE MIGRATION
To stop dye migration in its tracks, you need a way to prevent the gassy dyes from meeting plastisol ink. To do that, you need a blocker base. A blocker base is an ink made of dye-blocking ingredients. For example, Barrier Black is chock-full of carbon. That carbon will create a wall when printed and cured correctly, blocking the dyes from the rest of the print.
A carbon blocker base is an answer, but you need to use it correctly for it to do its magic.
Let’s start where screen printing begins — the design. A blocker base will behave just like an underbase, except for one thing. You do not want to trap or choke the blocker base. You want the underbase to print directly on top of the blocker base. If you choke it, then the sliver of white that touches the polyester could encounter dye migration. No thank you. Don’t trap.
To make a solid wall of ink to block the dyes, you need to lay down a thick layer of ink. So, it would be best if you had a lower mesh count like 110, and a thicker stencil.
Remember, you want to make a strong, solid wall of carbon to block the polyester’s dyes. Print a thick layer, then flash it. Be careful about flashing. If you get it too hot, the dyes in the fabric will get too rowdy, reducing the blocker’s ability to stop dye migration. Flash at 180°F-200°F for 2-5 seconds. You can print another layer of the blocker base, or go on to the rest of the colors.
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Keep that temperature low. If it gets too hot, the dyes will beat the blocker base and potentially cause dye migration. Keep the temperature low while still hitting the cure temperature. FN-INK™ is clutch when it comes to printing polyester shirts since it’s a low-cure plastisol ink. The ink only needs to reach 260°F for it to be cured, which is helpful when dealing with sensitive garments.
Save yourself from the dye migration nightmare. If you’re going to print on polyester, grab a blocker base, lay down a thick layer of ink, and keep temps low. You’ll have nothing but sweet dreams.