What The Heck is Dye Migration, Anyway?
In today's promotional product space, shirts constructed entirely of polyester or polyester blends (tri-blends, 50/50) are becoming more and more popular because of their softness. One of the most common questions we get is: Why does it cost more to print on garments with polyester or rayon in them? The answer is that, when decorating garments consisting of polyester, the screen print process requires a few tweaks due to an effect that can occur called "dye migration."
What is dye migration and why is it a problem?
Dye migration is the movement of particles of dye from the fabric into the ink imprinted on a garment. This causes discoloration or tinting of the imprint. For example, if you laid down plain white ink on a red polyester shirt, chances are the white will end up becoming a faded pink color instead.
When does this reaction occur?
The issue occurs in the later stages of the decoration process during the step of “curing." Curing is essentially the heating and drying of screen printed inks to set them and ensure their durability. The printed garments are placed on a large moving belt, which passes them below a heat source usually set at 320 degrees. After being exposed to these temperatures for a controlled period of time, the ink on the apparel is now considered cured. However, this heat is also exactly what precipitates the chemical reaction behind dye migration.
Unfortunately, heat is an integral part of the way we ensure excellent quality, solid imprints that are built to last, so we are always looking for different ways to sidestep these problems in the screen printing field.
What are the potential side steps for Printing on Polyester?
The most common side step to printing on polyester, cotton/poly and tri-blends is to use a white or grey "blocker" underbase. This adds an additional solid layer of ink under the entire print area that will block the dye from migrating into the visible print during the curing process.
It is important to remember this adds another layer of ink to your prints causing them to feel a little thicker on the garment. It's always good to stay away from using logos that cover a large surface area of the garment to avoid a heavy patch like feel.
Sometimes we will recommend our customers go for a vintage distressed look, which works great for tri-blends, etc. We don’t use an underbase white, and the dye migration actually helps achieve that washed out vintage look.