Types of Silk Screen
The silk screen printing technique is used for many applications, both industrially and at home. The essential elements and printing methods are the same whether mechanized for rapid, high-quantity output or improvised for art or fabric printing at home. The technique has remained almost the same since it was first used many centuries ago, although there have been changes and developments in the types of materials used.
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Terminology
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"Silk screen printing' and "silkscreening" are general terms used to describe a particular type of printing in which ink is pressed through a stenciled mesh screen onto fabric, paper or other substrates. The more accurate term for this type of printing is "screen printing." Screen printing has been traced back to ancient China, where silk was traditionally used for the mesh screen. Although the use of silk for screen printing was once common worldwide, silk tends to loose tautness and will deteriorate with use of chemicals so it has now been replaced almost entirely with synthetics.
Basic Principles
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The basic principles and processes involved in screen printing have remained similar throughout centuries of use. A rectangular frame holds a fine mesh screen taut. Sometimes, a stencil is placed behind the screen. More commonly, however, a stencil is applied to the screen with some kind of ink-resistant emulsion. The stencil is a negative image of the artwork to be printed. The screen is placed over the substrate material and ink or paint is poured onto the top of the screen. A squeegee spreads the ink over the screen, forcing it onto the substrate in the spaces not stenciled off. The ink cannot pass through the emulsion or other stencil material, leaving the desired image with clearly defined edges on the substrate. The thread count of the mesh determines how much ink can pass through.
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Industrial Silk Screens
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Modern industrial silk screening uses machines and materials designed for efficient, top-quality printing. Industry standards have developed to reduce waste and ensure the best print results. There are three types of presses: flat bed (the most common); cylinder and rotary. They are manually or automatically operated. The frames are usually metal. Aluminum is generally preferred because it is lightweight yet strong. Screens are now usually made from monofilament nylon or polyester. Finer mesh screens (which have more threads per inch) are used with more viscous ink for fine detailing. Coarser mesh screens (with fewer threads per inch) are used with thicker inks and generally only for textile printing. Four separate screens are used with the four process colors of ink to create the full spectrum of colors. The stencil is often applied photochemically using a negative image transparency and light-sensitive emulsion that hardens when exposed to UV light. Frames are washed and re-used multiple times.
Homemade Silk Screens
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Artists and craftspeople make and use silk screens for home-printing with a variety of applications. They are often used to print designs on T-shirts and other textiles. There are screen printing kits available. Some provide photo emulsion to use for professional-standard printing, while others are much more basic. The materials needed can also be purchased separately or improvised. An old wooden picture frame with a piece of fine mesh fabric stapled makes an inexpensive and functional alternative. You can make stencils to use with a home silk-screen by cutting shapes from paper, wax paper or card stock. The stencil is taped to the reverse of the screen to resist the ink. Glue makes an improvised alternative to emulsion for applying a stencil design directly to the screen.
Applications
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Silk screening is usually associated with T-shirts and other garments, but the technique is used to make a wide variety of products. The advantage of screen printing is that it can be used on substrates of almost any material, size and shape. Screen printing is used on items as diverse as balloons, clock faces and glassware. Modern technology means a customer can supply a printer with virtually any image, artwork or text to be rendered with screen printing.
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