If you’ve ever screen printed a blended fabric such as 50% cotton/50% polyester garment and all the way up to 100% polyester, you likely have experienced dye migration. In simple terms, dye migration means the white ink printed on a red t-shirt turns pink inside your conveyor dryer.
Your first option to attack this discoloration problem is to use a High Opaque/Low Bleed ink. This ink will help to block the dyes from reaching the ink surface. Notice I said Low Bleed? That’s because there’s no such thing as a No Bleed ink. Other factors will impact the amount of dye migration as well.
Dye migration is the result of dye from the polyester fibers releasing into the ink film, and floating up to the ink surface. The dye in the cotton portion of a blended fabric will not migrate. That’s why you don’t experience this dye migration problem when printing 100% cotton garments. If you print any blended or 100% man-made fabrics, you are at risk of dye migration in your inks. You’ll see this issue more frequently with red, kelly and maroon garments, but the risk of dye migration exists with other blend and 100% polyester colors as well.
The primary factor impacting dye migration in your shop will be excessive heat during the curing process. Many screen printers operate their conveyor dryers at much higher temperatures than necessary to cure plastisol inks. This fact goes unnoticed until blended fabrics enter the mix. Heat causes the dye to release from the polyester fibers. More heat equals accelerated release of the dyes into the ink. It is important that your garments reach the proper curing temperature for the ink, but no higher. This will require some testing of your equipment.
Tip: At the end of the dryer belt, do not allow blend garments to fall into a box or catch basket. Before stacking, shake garments to cool. Heat from stacked garments can draw dye from the garment on top into the ink on the garment below.