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FLEXO Magazine : November 2010
Technologies & Techniques Right Tape/Right Plate: How Do I Tell? Plate, Press, Cylinder Key in Determining Best Fit By David A. Watson. Plate technology has not only changed the way print- ers are printing, it has also changed the way plate mounting tape manufacturers are recommending plate mount tapes for printing jobs. Years ago, if someone asked for a recommendation of plate mounting tape for a specific job, the standard answer most likely would have been “soft density tape for process; medium density tape for combination; and hard density tape for solids and line work.” With the introduction of digital plate technology, today the answer to the same question would likely be determined by a series of questions: 1. Are your plates analog or digital? 2. What is the durometer of the plate material you are using? 3. What type of press (wide web or narrow web) are you running? 4. Are you using sleeves or metal cylinders? In today ’s printing market, this information is needed to most accurately recommend the correct density plate mount- ing tape for the job. When digital plates are created, the dots have a much steeper shoulder than the dots of an analog plate. Due to the dot shape, firmer tapes provide better support of the dots, allowing the ink transfer needed to achieve good quality dots and desired Solid Ink Density (SID). When using a combination of digital plate and soft plate mount tape, the tape will not be firm enough to support the dots for adequate ink transfer onto the substrate, resulting in low solid ink density (SID). When this happens, the natural compensation is to apply more impres- sion between plate and substrate in an attempt to achieve better ink transfer. This typically results in dots with halo’s and solids that have pin holes or look washed out. In this case, the more impression applied, the worse the outcome. Durometer of plate material, type of press (narrow or wide web), and cylinder type (sleeve or metal) also play a critical role in properly specifying plate mounting tapes for best results. Plate durometer (hardness) can be discussed in terms of soft (below 45 durometer), medium, (45-65 durometer), and hard (over 65 durometer). In wide-web sleeve printing for process and combination, both medium and hard plates can achieve the best printing results utilizing a medium density tape. Print sleeves are softer and have some “give” in them, so a medium tape needs to be used. When printing wide web with sleeves for large solids and whites, a hard plate with a hard tape works well, while a medium plate with a hard tape also provides great results. • Wide-web printing with metal cylinders will typically fol- low the old rule of thumb: soft/medium tape for process, medium tape for combination, and solids and whites on hard tape. This is due to the hardness of the metal cylin- ders which offer minimal or no “give”. • Narrow web printers also use the same guidelines as wide web cylinder printers because the harder the tape, the more chatter that is noticed in the print. Pairing the correct plate with plate mounting tape is more critical now that ever. To achieve the best print quality, life of plate, and best print results, it is always recommended that printers conduct trials to determine the best printing results for the printing conditions. n About the Author: David A Watson is a PPF Sales Executive at tesa tape Inc. , Charlotte, NC. • Collect information first, then select tape. • Firmer tapes support dots, afford good ink transfer. • Plate durometer, press platform, cylinder characteris- tics determine tape specification. Photo courtesy tesa tape inc. 54 FLeXO novemBer 2010 www.flexography.org 44071_ENGLISH.indd 1 10/27/10 7:16:08 AM FLX_Nov10_mech.indd 54 11/1/10 2:25 PM
Sustainable Fall 2010