Flexography


Screen Printing

Everyone thinks of T-shirts when they hear screen printing (also known as serigraphic printing), but I've worked with a few screen printers and, believe me, the only t-shirts around were on the backs of the employees. The opportunity for creativity in large form is astounding. I've witnessed everything from billboards to vehicle signage, to outdoor signs to 3D in-store retail displays that would really knock your socks off.

This method of printing is appropriate for signage; printing on fabric; novelty items; and unique surfaces like glass, circuit boards, wall coverings, and even linoleum. This method of printing uses process as well as spot color inks; however, they are formulated thicker and dry more quickly. Signage requires that these inks be able to stand up to all sorts of environmental issues. Substrates are much more varied than offset and, beyond paper, choices include plastic, nylon, and all sorts of synthetics in between.

Screen printing is a printing process in which positive films are used to expose photosensitive stencil and the wet stencil is applied to the fabric screen (the equivalent of a plate). As the stencil dries, it adheres to the fabric plate. The plate is mounted on a press that looks like a series of tables. The substrate feeds its way through each press unit. At the first unit, the screen is lowered to the substrate, ink floods the screen, and is then squeegee'd through the screen to the substrate below. Then the substrate moves on to the next unit until all color is applied. After the piece moves off press, it enters a finishing area where options including mounting, sewing, grommets, and vents are applied.

Innovations in screen printing include direct-to-screen technology, which eliminates the use of filmmuch like computer-to-plate technology for offset printing. A computerized mechanical head sprays wax onto the screen or plate in the negative areas, leaving areas of mesh for ink to pass through. It is extremely fast and accurate.

Additionally, because there is so much expertise in large format signage with commercial screen printing, many of these commercial printers have added wide-format digital output devices as well. Run lengths and the types of ink/substrate combinations dictate whether a job will run conventional or digital.

Substrates and inks in screen printing are different from offset, and creatives therefore need to think differently when they design for this process. The substrates typically found in screen printing range from paper to fabric to plastic and all types of synthetic materials selected for their ability to endure all kinds of environments. Because of these substrate choices, inks for screen printing tend to be thick. However, drying time can be boosted with heat sources and, like the synthetic substrates, these inks can withstand a variety of environmental considerations. Signage tends to image a lot of solid color, so trapping is intense in this line of printing (as it is in packaging) and these jobs must be carefully planned. Colored substrate is not uncommon in this application, and there are many methods for employing white inks under other inks to achieve your color choices.

This is definitely a printing method that warrants consultation prior to the creative process getting started so that you fully understand how to construct for the screen process and the limitations of the process when it comes to attempting something such as matching a screened sign to an offset produced piece. Different methodologies, delivery mechanisms, substrates, and inks make that a challenging request; however, it can be done. As one of my clients told me with a wink, "The magic is in the ink."

Tip

For more information about this printing method and for a firsthand look at technologies innovating this industry, check out SGIA.org. Their annual trade show is typically held in the fall in New Orleans. Here you will see all manner of large format specialty graphics.




Adobe InDesign CS2 @work. Projects You Can Use on the Job
Adobe InDesign CS2 @work: Projects You Can Use on the Job
ISBN: 067232802X
EAN: 2147483647
Year: 2003
Pages: 148

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