First, the image is separated into up to 4 colors. Then each color is printed on a piece of clear plastic in black. Then the sheet of plastic is taped to a printing screen which has a light-sensitive gel on it, and exposed to light. Then the screen is washed, and only the area where the image was can pass paint through. Then the screen is attached to a printing press where shirts are run through, and each color is added to the shirt. Then the shirt is run through a dryer (like a Pizza oven) on a conveyor belt, and folded.