Dye Migration is a process that occurs in polyester garments. Poly fibers start to melt at 300F+, and in doing so they release the dye of the garment, which in turn changes the color of the ink printed on the shirt. For example, if a red 50/50 blend shirt is printed normally, and cured at 320F, then the white ink printed on it will gradually turn pink as the red dye migrates up into the ink.
You may also see this as "bleeding". "Bleeding", occurs when residual dyes in a garment migrate their way into the ink film. The cause could be with the garment (not properly prepared for printing or as a result of the finishing method in manufacturing) or the inks (not properly cured). Bleeding can be controlled on most garments through proper controls on ink selection, application, and curing.
This can be controlled by the use of either a low bleed ink, or a low cure ink. A white that has bleed resistant properties and can be printed on 50/50 blends is Wilflex Lava Low Bleed White. If you're looking for standard colors in a low cure ink, then you can look to the Top Score line from Wilflex.
As with all inks, preprint and test all fabrics for dye migration, ink adhesion, wash fastness and other desired properties before beginning any production.
Here is a great article on Dye Migration!
- Dye Migration (2).doc