Printing water based acrylic ink on polyester is ideal. There’s less chance of dye migration and can yield a light ink deposit on thin garments. When talking about polyester, the first thing that stands out for this type of garment is the low stitch density of the polyester, which will make it very porous. The thickness of polyester is very thin; In addition, the garment is often completely saturated with dye and the difficulties can be even further exasperated if the polyester is holding a percentage of lycra/ rayon in it. Lycra is a synthetic fiber that does not hold any dye. Instead, the dye will simply rest around the individual fibers add to an over-saturation of dye on the garment, making dye migration more likely to occur.
Printing with an under-base blocker is crucial for quality prints, however, to maximize the effectiveness of an under-base blocker and the additional white under-base, it is important to have minimal pressure where the fabric and the screen meet. To achieve this, you can change your squeegee or squeegee angle, increase tension on the screen, change the off-contact, and etc. The key is to work with what you have to achieve that minimal penetration into the fabric so the final print will have a soft-hand feel and be opaque with no dye migration. In addition, the flood bar height is a little bit higher with water base printing as we are not simply moving the ink back up to the base of the screen for another pass. We are glazing over the screen a thin layer of ink to cover the screens, insulating moisture to prevent clogging (as can be seen in the video above).
In the squeegee angle chart, we see the type of deposit we can expect with each type of angle. At Matsui, for the most of our ink we recommend usually 65°, The viscosity level is a little lower usually for water base inks, so if you are currently using plastisol, you will most likely need to adjust slightly for optimal printing.