Since 2008, Vacord Screen Printing has been known for discharge screen printing. Founder of Vacord, Stuart, ordered a sample of Matsui brand discharge ink back then from his distributor and immediately fell in love with the ink. He had only been using waterbased inks, and was concerned with their limitations on dark shirts. But once he saw the potential of discharge ink, he explored it further and started writing about it on the Vacord blog, Discharge Nation. He's since written about it, wanting to share the knowledge with other printers (a rare act in the industry), and has done discharge test printing for Fruit of the Loom and other large companies.
Discharge ink is a type of waterbased ink. It works by removing the fabric's dye color and optionally replacing it with another color. Waterbased inks contain pigment held in a water based solution of varying viscosity, and can air dry. The discharge inks, however, require a lot of heat energy to activate. They go onto the garment almost clear looking at times, and then once passed through a conveyor belt oven, the chemicals activate and the "bleaching" effect takes place. It takes a lot of time and energy for a proper cure of a discharge print, so large, professional screen printing ovens are needed. Some regular waterbased inks can be wash-fast without curing with heat.
The example below is an Anvil 980 shirt in the Moss Green color. The shirt has been printed with bright clear discharge ink with a black trim. On the enlarged section, you can see how the discharge ink has removed the shirt's color to become nearly white, like the raw cotton's original color.
Traditional ink, or plastisol, is PVC-based ink (polyvinyl chloride) and is considered a solid ink. It can never dry on its own, and requires being cured with heat. It's a wonderful solution for cases where the garment can't be printed with discharge ink, such as blend shirts, hoodies, or athletic wear. Polyester cannot use discharge ink, so all Dri-Fit and 100% polyester athletic clothing requires plastisol printing for best results.
The two images below are good examples of using just one layer of plastisol ink on heather blends. This results in a soft print with a vintage look to it, and is something we specialize in. Click the images for a larger view.