(n.) - The movement of dye from one part of a textile material to another.
Polyester fabrics are notorious for dye migration. You may have noticed this with dark-colored jerseys, the white numbers or letters on the back become tinted to the color of the jersey. This occurs when the item is being made and is actually caused by heat. The high temperatures used to cure the ink causes the dye in the garment to turn into gas. The gasified dye then migrates from the garment to the ink, hence the term dye migration.
Some colors are more commonly have issues with dye migration, red being the most notorious offender. Generally the rule of thumb is the darker the color the more migration will occur, but all colored polyester garments will have some form of dye migration.
Dye Migration Can Be Mitigated
At Theds we take some steps to prevent dye migration on polyester shirts. We use specially formulated, "low bleed" inks for polyester printing. These polyester specific inks better adhere to the synthetic fibers and reduce the migration of dye from the garment. The low bleed inks will not completely eliminate dye migration for difficult colors like red. For these particularly difficult colors, we use a blocking underbase print of gray ink. We will then print the final design on top of the gray underbase. The darker gray absorbs the migrating ink and prevents color distortion of the visible top print.