Silk screening is a method for printing T-shirts that involves a polyester piece of sheer fabric stretched over a wooden frame the size of the shirt. A thin piece of plastic is put over the screen with holes in it where ink will appear on the shirt.
Next, the shirt is placed on a firm board and the screen is pressed on top of it. The screen is covered with thick ink using a sponge, fill blade or squeegee that forces the ink to flow through the screen's holes and onto the shirt. If multi-colored designs are desired, this process is repeated for each color, with the lightest color applied first and moving up to the darkest. Originally, silk was used as the screen fabric rather than polyester.
An alternative to traditional silk-screening is to use iron-on transfers. With these, a design is ironed onto a shirt while a customer waits. The design bonds to the shirt when it is heated up.
Screen printing is not just used for T-shirts but is also used in a variety of industries such as balloons, product labels, signs and displays. Screen printing was introduced to Western Europe from Asia in the late 18th century.