Printing Technology
Screen Printing
Screenprinting, silkscreening, or serigraphy is a printmaking technique that creates a sharp-edged image using a stencil. A screenprint or serigraph is an image created using this technique.
It began as an industrial technology, and was adopted by American graphic artists in the early 1900s. It is currently popular both in fine arts and in commercial printing, where it is commonly used to print images on T-shirts, hats, CDs, DVDs, ceramics, glass, polyethylene, polypropylene, paper, metals, and wood.
Graphic screenprinting is widely used today to create many mass or large batch produced graphics, such as posters or display stands. Full color prints can be created by printing in CMYK (cyan, magenta, yellow and black). Screenprinting is often preferred over other processes such as dye sublimation or inkjet printing because of its low cost and ability to print on many types of media.
Printing technique
A screen is made of a piece of porous, finely woven fabric (originally silk, but typically made of polyester since the 1940s) stretched over an aluminum frame. Areas of the screen are blocked off with a non-permeable material to form a stencil, which is a positive of the image to be printed; that is, the open spaces are where the ink will appear.
The screen is placed atop a substrate such as paper or fabric. Ink is placed on top of the screen, and a fill bar is used to fill the mesh openings with ink. The operator begins with the fill bar at the rear of the screen and behind a reservoir of ink. The operator lifts the screen to prevent contact with the substrate and then using a slight amount of downward force pulls the fill bar to the front of the screen . This affectively fills the mesh openings with ink and moves the ink reservoir to the front of the screen. the operator then uses a squeegee (rubber blade) to move the mesh down to the substrate and pushes the squeegee to the rear of the screen. The ink that is in the mesh opening is transferred by capillary action to the substrate in a controlled and prescribed amount, i.e. the wet ink deposit is equal to the thickness of the stencil. As the squeegee moves toward the rear of the screen the tension of the mesh pulls the mesh up away from the substrate leaving the ink upon the substrate surface.
Textile items are printed in multi-color designs using a wet on wet technique, while graphic items are allowed to dry between colors that are then printed with another screen and often in a different color. The screen can be re-used after cleaning.
While the public thinks of garments in conjunction with screen printing, the technique is used on tens of thousands of items, decals, clock and watch faces, and many more products.
Versatility
Screenprinting is more versatile than traditional printing techniques. The surface does not have to be printed under pressure, unlike etching or lithography, and it does not have to be planar. Screenprinting inks can be used to work with a variety of materials, such as textiles, ceramics, metal, wood, paper, glass, and plastic. As a result, screen printing is used in many different industries, from clothing to product labels to circuit board printing.
A simple screenprinting technique