Discharge ink has a chemical (formaldehyde) that essentially bleaches the dye out of the garments. It’s especially useful for dark or colored garments– but can only be used effectively on 100% cotton. When you “discharge” the dye from a garment, you’re creating an (almost) white base.

Printing dark garments with Plastisol, on the other hand (or should I say heavier hand), requires a layer of white ink to create an opaque underbase to print vibrant colors. It can make for a heavier print even before layering all the colors on top. There are thinners and techniques to reduce the ink deposit, but truly soft-hand Plastisol prints are the exception, not impression à chaud  the rule. Bottom line: Water-based inks succeed in achieving the softer and more lightweight hand between these two inks

Plastisol ink has better color vibrancy
Color vibrancy (brightness, saturation) is where Plastisol shines, especially on darker garments. Water-based inks can produce a vibrant print on lighter garment colors, but still not as well. When you need your colors to be rich and brilliant and pop off the print, go with Plastisol screen printing. It’s one of the reasons it remains the long-time industry standard.

The reason is similar to why it has a heavier hand: the layer of plasticized ink covering the color of the garment. Plastisol is considered a 100% solid, so every bit of it stays on the fabric when cured. This blocks the dye and creates a mostly opaque underbase to print bright, bold colors– even fluorescent colors and specialty inks such as glow-in-the-dark and puff.