Screen-printing

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"Silkscreen" redirects here. For the typeface, see Silkscreen (typeface)

Screenprinting, or serigraphy, previously known as silkscreening 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.

In electronics, the term screenprinting often refers to the writing on a printed circuit board. Screenprinting may also be used in the process of etching the copper wiring on the board or computer chips.

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 media.

1 History
2 Printing technique
3 Stenciling techniques
4 Versatility
5 External links

[edit] History

Screenprinting has its origins in simple stencilling, most notably of the Japanese form (katazome), used on textiles, mostly for clothing. This was taken up in France. The modern screenprinting process originated from patents taken out by Samuel Simon in the early 1900s in England. This idea was then adopted in San Francisco, California, by John Pilsworth in 1914 who used screenprinting to form multicolor prints in much the same manner as screenprinting is done today.

Screenprinting took off during the First World War as an industrial process for printing flags and banners. The use of photographic stencils at this time made the process more versatile and encouraged widespread use.

[edit] Printing technique

A screen is made of a piece of porous, finely woven fabric (originally silk, but typically made of polyester or nylon since the 1940s) stretched over an aluminum frame. Areas of the screen are blocked off with a non-permeable material—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 on top of a piece of dry paper or fabric. 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. The ink passes through the open spaces in the screen onto the paper or fabric below; the screen is lifted away and then the squeegee is pushed back across the screen, with the screen lifted, "flooding" the ink into the screen. The screen can be re-used after cleaning. If more than one color is being printed on the same surface, the ink is allowed to dry and then the process is repeated with another screen and different color of ink.

While the public thinks of garments in conjunction with screen printing, the technique is used on tens of thousands of items, including birthday cake designs, decals, clock and watch faces, the electromagnetic faces of Palm Pilots and so much more. The vast majority of silk-screen printings are monochromatic.

[edit] Stenciling techniques

A macro photo of a silk screen with a photographically produced stencil. The ink will penetrate where the stencil does not cover the fabric.

There are several ways to create a stencil for screenprinting. The simplest is to create it by hand in the desired shape, either by cutting a piece of paper (or plastic film) and attaching it to the screen, or by painting a negative image directly on the screen with a filler material which becomes impermeable when it dries. For a more painterly technique, the artist may choose to paint the image with drawing fluid, wait for the image to dry, and then "scoop coat" the entire screen with screen filler. After the filler has dried, a hose can be used to spray out the screen, and only the areas that were painted by the drawing fluid will wash away, leaving a stencil around it. This process enables the artist to incorporate their hand into the process, to stay true to their drawing.

A method that has increased in popularity is the photo emulsion technique:

The original image is placed on a transparent overlay. The image may be drawn or painted directly on the overlay, photocopied, or printed with a laser printer, as long as the areas to be inked are opaque. A black-and-white negative may also be used (projected on to the screen). However, unlike traditional platemaking, these screens are normally exposed by using film positives.
The overlay is placed over the emulsion-coated screen, and then exposed with a strong light. The areas that are not opaque in the overlay allow light to reach the emulsion, which hardens and sticks to the screen.
The screen is washed off thoroughly. The areas of emulsion that were not exposed to light — corresponding to the image on the overlay — dissolve and wash away, leaving a negative stencil of the image attached to the screen.

Photographic screens can reproduce images with a high level of detail, and can be reused for thousands of copies. The ease of producing transparent overlays from any black-and-white image using a photocopier makes this the most convenient method for artists who are not familiar with other printmaking techniques. The low resolution and size limitations of a photocopier make film positives necessary in professional screen printing environments. Artists can obtain screens, frames, emulsion, and lights separately; there are also preassembled kits, which are especially popular for printing small items such as greeting cards.

Novice screenprinters often overlook the importance of "squeegee pulling," that is, the act of pushing ink through the holes between fibers in the screen's mesh to produce the final product. A steeper angle (laying the squeegee down flat handle facing the person inking) will naturally push more ink through the screen, whereas having the squeegee perfectly vertical will push a minimal amount of ink through the screen. Depending on the definition and quality the item being printed on requires, a variation between the two angles will be necessary.

[edit] Versatility

An example of screen-printing used on Woodblock Graffiti.

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.