The process of screen printing is easy. In theory, it is printing an image using a photo emulsion technique. Generally speaking, you use paint on a screen that is exposed to light, allow it set, put your picture on top after it has dried and then cure it with heat. The area of the screen that is covered up by your design will not get cured. After you expose your image, all of the areas underneath your image will just wash away with water. The area in the shape of your design is your pattern that you will use to create your screen printed t-shirt. The first thing you need to do is decide on your idea. You can print it onto plain or transparency paper, as long as the image is opaque. Cover your screen with photo emulsion using a squeegee. It reacts to light so make sure to do this part in an entirely dark room. Cut out the design and lay it on the back of the screen. Expose your image to light for about 30 minutes. Rinse it with water until a picture appears clearly. Place the screen over your shirt and drag ink over the concept with a squeegee. Cure it with a flash dryer or heat gun to make sure the image sets. Take a look at the below infographic for more details.
Infographic courtesy of ShirtSpace.com