Screen Printing, which is also known as silk screen printing is a badass method of printing graphics on a t-shirt using thick inks that lay on top of the shirt rather than soaking into the shirt. Screen Printing is what most companies use and, back in the day, was the only major way to create bulk amounts of custom t-shirts.
With thicker inks, screen printing is better for graphics with only one or two ink colors being used.
So how does Screen Printing work? Well it's old school. Instead, a thin mesh is stretched tightly over a frame (originally the screen was made from silk, it's made of polyester today). A negative of the design is printed onto the screen to be placed against the shirt. Once set correctly, ink is rolled over the screen, only the areas where the design has been printed allows ink to slip through. The ink then sets on the t-shirt and is put aside to dry.
We’ll be honest with you, it’s a lot more complicated than that. There’s a lot of separate chemicals, inks, and techniques that go into making your shirts, but that’s the intro.