Screen printing

Screen printing is a printing technique whereby a mesh is used to transfer ink onto a substrate, except in areas made impermeable to the ink by a blocking stencil. A blade or squeegee is moved across the screen to fill the open mesh apertures with ink, and a reverse stroke then causes the screen to touch the substrate momentarily along a line of contact. This causes the ink to wet the substrate and be pulled out of the mesh apertures as the screen springs back after the blade has passed. Screen printing is also known as silk-screen, screen, serigraphy, and serigraph printing. Multiple colors can be used, with the use of multiple stencils.

History

The technique of screen printing first appeared in a recognizable form in China during the Song Dynasty (960–1279 AD). It was then adapted by other Asian countries like Japan, and was furthered by creating newer methods. Screen printing was largely introduced to Western Europe from Asia sometime in the late 18th century, but did not gain large acceptance or use in Europe until silk mesh was more available for trade from the east and a profitable outlet for the medium discovered.

Materials

Screens

The screen is made from porous, finely woven fabric held in a frame of wood or metal. Commonly used mesh materials include polyester. The material to be printed on is placed under the screen, and the frame is then pressed down onto the material.

Inks

Screen printing inks are thicker than the ones used in other printing processes, allowing them to create vibrant colors even on dark backgrounds. The viscosity of the ink can be adjusted according to the print job.

Stencils

Stencils can be created in a variety of ways, including hand-drawn, painted, or photo-emulsion techniques. The photo-emulsion method involves coating a mesh screen with a light-sensitive emulsion, then exposing it to light through a film positive of the desired image. This hardens the emulsion not covered by the film, and the unhardened portion is washed away, leaving a clear imprint of the image on the mesh.

Process

The basic process of screen printing involves creating a stencil on a screen of porous mesh. The screen is placed atop a substrate. Ink is placed on top of the screen, and a squeegee (rubber blade) is used to push the ink evenly into the screen openings and onto the substrate below. The ink passes through the open spaces in the screen onto the substrate below; then the screen is lifted away, and the substrate is left to dry, completing the print process.

Applications

Screen printing is used in a wide range of industries and applications, including textiles, ceramics, wood, paper, glass, metal, and plastic. This versatility makes it a preferred method for printing designs on T-shirts, posters, billboards, and more. It is also used in the production of electronic devices, including circuit board printing.

Advantages and Disadvantages

Advantages

• Versatility in printing on various substrates
• Durability of printed items due to the composition and thickness of the inks used
• Ability to produce vibrant colors, even on dark substrates

Disadvantages

• The process can be time-consuming for multi-color prints, as a separate screen is required for each color
• Initial setup costs can be high due to the need for multiple screens
• The process is not ideal for high-volume, short-run print jobs

See Also

• Lithography
• Flexography
• Digital printing

External Links

• Screen Printing & Graphic Imaging Association International
• Screenprinting & Graphic Imaging Association

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