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FLEXO Magazine : February 2010
www.flexography.org FEBRUARY 2010 FLEXO 35 TECHNOLOGIES & TECHNIQUES the raw material near direct heat sources. While humidity is not a direct threat to the material, boxes should be kept dry, as direct exposure to water could affect box strength and compromise the protection of the contents. When storing these boxes, only those of the same size should be stacked upon one another. Putting a smaller box on top of a larger box could compress the lower box and compromise the quality and uniformity of the material in the lower box. Stacking a larger box on top of a smaller container leaves the edges of the material unsupported and could result in the release of the protective cover sheet(s). Boxes of raw material should also be equal to or smaller in size than the pallet used. Boxes left to overhang pallets or shelves will also be unsupported and are susceptible to damage. Inside each container should be paper or foam liner sheets, which separate each raw sheet of polymer. When stor- ing and stacking finished plates, these foam sheets are used to prevent damage by layering foam sheets between each stacked plate. Some polymer manufacturers recommend not stacking plates more than 6in. high. THE PLATEMAKING PROCESS It is in platemaking that the UV light sensitive material becomes vulnerable. UV light blocking film, shields, or tubes should be used on lighting inside the plate room, including over the fluorescent lamps inside the light table. While UV light is the source of polymerization of the material, it can also pre-expose raw material or damage finished plates. If the temperature of the platemaking rooms differs greatly from the raw material storage area, the raw material should be adapted prior to the manufacturing of the plate. Once the platemaker trims the raw material to the desired size, the remaining material to be used later should immediately go back into the box or drawer that assures it is protected from UV light and ozone. Other than handling the material with great care when going from one stage of the platemaking process to the next, the plate maker's ability to affect plate life is primarily through optimization, testing, and verification of the exposure, processing, drying, and finishing processes. Through the use of a back exposure test, the platemaker determines the time required to achieve proper plate relief. Excess plate relief results in image areas lacking support and premature wear, especially in screen and process areas. The main exposure text is used by the platemaker to ensure that the image is well supported and adequately anchored to the floor, while holding areas requiring a minimum dot and not filling in reverses. Both over and under exposed plates will most certainly lead to a plate lacking longevity. The processing test is used to determine the minimal amount of time required to remove the un-polymerized mate- rial down to the floor. This process is true of solvent, thermal, and water processes. Failure to remove all of this unwanted material will affect plate relief, and sometimes affect the uniformity of the plate floor. If the plate was not completely dry before going into post exposure and light-finishing, solvents could be locked into the plate surface and affect finished Reduce your costs and keep quality up, thanks to its X-clusive features: •Gearless Technology •Vision System -- one-touch auto register control •X-tra short web path Let the X-Flex set a new benchmark for your company. The all new X-Flex is designed to shrink your problems down •X-tremely reduced waste •X-tra short set up time •X-tremely compact footprint •X-tremely easy to adjust and operate •X-tra flexibility X-Flex platform redefines the market in narrow web printing technology. X-celerate your productivity Innovation With Passion Lecco -- Italy www.omet.it Winner of the Technical Innovation Award 33, BROOK STREET CT 06110 WEST HARTFORD USA U.S.A. Tel: 860 2322323 Fax: 860 2330162 www.matik.com Distributed in North America by: