We use various inks to bring your concepts to completions on t-shirts.
Plastisol is used as ink for screen-printing on to textiles. Plastisols are the most commonly used inks for printing designs on to garments, and are particularly useful for printing opaque graphics on dark fabrics.
Discharge ink is used to print lighter colors onto dark background fabrics, they work by removing the dye of the garment - this means they leave a much softer texture. The cons with this process is that they are less graphic in nature than plastisol inks, and exact colors are difficult to control. One of the pros of using this process is they are especially good for distressed prints and under-basing on dark garments that are to be printed with additional layers of plastisol. It adds variety to the design or gives it that natural soft feel. (from wiki)
Hydro-Chromic White is a special binder, which changes repeatedly from white to transparent when wetted with water and changes back to the original white when dried, for screen printing onto cotton, polyester, nylon, their blended fabric, nonwoven fabric, and other fabric. Therefore, through printing the binder over a design, it is concealed with white in dried condition and appears when the binder becomes transparent with water.