Dye migration is also known as sublimation and if you’re printing on a red garment it can turn your white screen printed graphics *gasp* pink. In plain chemistry speak the dye from the fabric is transformed (sublimed) from solid to gas when the screen printed graphic is heat set. Typically the most troublesome fabric is a polyester blend. To dye polyester, the manufacturer must heat set at high temperatures.
To cure plastisol inks, (screen printing inks) the printed fabric is run through a conveyor gas dryer which can cause sublimation of the garments dye. To further complicate the issue, while screen printing, we use flash-curing screen presses. These are “stations” on the press that are used when printing large-scale jobs or jobs that require many layers of different colored inks to complete the graphic. Flash-curing occurs to dry separate layers of ink during the screen print. It's during these stages of screen printing, bleeding or dye migration can take place.
The sublimed gas can get sucked into the ink leading to a discoloration of the graphic. Unfortunately, the actual event of the dye molecule attaching to the ink molecule can take some time. So the garment can look great coming off the dryer and so the job gets neatly packaged and shipped to the customer without the screen printer realizing there will be a problem. Experienced screen printers are familiar with the potential for the problem and take precautions when printing in conditions where sublimation may occur.
The images below are examples of dye migration. The white ink on the red fabric is a very light pink while the white ink on the black fabric appears to be a very light green.
Examples of Dye Migration
The most obvious course of action is to control heat so sublimation of the garment dye does not take place. This is not as easy as turning the temperature down on the conveyor gas dryer. If the heat is turned down too much, the plastisol ink will not cure and the screen print will be prone to wash out. The temperature and humidity in the room and the garment itself must be taken into account along with the speed at which the garment is conveyed through the dryer along with consideration to the thickness of the ink layer(s).
Consistently adjusting for temperature, even in the middle of processing a screen printing job is critical. Our screen printers have to pay attention to the fact that the plantens (boards where the garment rests during the screen print) may heat up during the course of the job. Our screen printers also use a timer on the flash cure arm of the press. This ensures that if there are other difficulties during the print, no one garment is overheated making it prone to dye migration.
We use the highest quality, manufacturer designated low-bleed inks as well as carefully controlling temperatures, plus we only offer quality products for our customers to choose from. Low quality apparel products are more prone to dye migration simply because the manufacturers of cheap products may not go through the lengthy processes of curing the dye to the fabric.