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FLEXO Magazine : February 2012
The larger the difference in the b* value (-3 , -4 , -5 , - 6), the more optical brighten- ers there are in the paper. Or, the other option is to turn off the lights and using a black light illuminate the customer’s proof and the press sheet. The white, non-printed area of the proof will shine bright white, while the white area of the press sheet will be muted by several levels of magnitude when compared to the proof. Here are three solutions for compen- sating for optical brighteners: • Install UV blocking filters. If the proof is being viewed in a light booth, you can install UV blocking filters over the D5000 bulbs so when comparing the proof to press color match, these filters will help your eye ignore the optical brighteners in the paper • “Accept and ignore” the fact that there are optical brighteners in the paper and use a spectrodensitom- eter to measure the color in the proof, and in a D5000 light booth, visually match the proof to press as close as possible. This requires that you educate the customer on optical brighteners and the inher- ent issues in matching the proof to the press. Bring the customer to the light booth, show them the visual differences and make sure they acknowledge their understanding for the visual differences • Create a proof using FIRST, ISO, Gracol, SWOP, etc. industry stan- dard compliant materials. This proof will better visually match what will be printed on press. You may question why proofs cannot be printed on the actual material that is going to be used on press. While this is possible, it is not practical. Inkjet inks require a receptive coat- ing be applied to properly bond to the press paper Printing on translucent materials is also very common in package printing and offers some very unique chal- lenges. The color of the backdrop, or the surface behind the proof or press sheet, can substantially influence both the visual and measured colors between the proof and/or press sheet. For example, when you view a printed piece of translucent material placed on a dark colored viewing surface, the color will look vastly different than when it is placed on a light colored viewing surface or when held up to an illumi- nated backlit surface. Taking measure- ments with a spectrodensitometer on all three different surfaces can validate the values. The measured L*a*b* values will be different when measured over the three different surfaces. By using an industry standard white, black or neutral colored background in a controlled viewing environment to both visually check and measure the colors using a spectrodensitometer, you can compensate for the translucent properties. Print standard ISO 12647-2 specifies the surface color value ranges for measuring materials with a spec- trodensitometer, which in turn offers you consistency and predictability when measuring translucent materials. 32 FLEXO february 2012 www.flexography.org HD-ITR Flat Top Dot Seamless Sleeves High Definition Flexo Technical Partnerships OEC Graphics is not simply a source for prepress. We are your graphics provider, brand developer, technical expert, press-side troubleshooter, equipment consultant and your means to establish even stronger relationships with your customers. Our goal is to grow your business by becoming technical partners. Together we can educate and inspire your customer base to expand on the relationship, growing business together. LISTEN. CREATE. DELIVER. • 50% More Color Space • Press-Neutral Technology • Drive Quality & Productivity TAKE YOUR FLEXO TO THE HIGHEST LEVEL Let OEC Graphics... Let OEC Graphics... Wisconsin . Chicago . California . Atlanta VISIT US AT INFO*FLEX 2012 BOOTH #418 REQUEST A SAMPLE... call Marshall Hogenson at 612.280.8472 or email email@example.com oecgraphics.com Spartanburg, S.C. USA 1-800-624-1985 www.laserengrave.com Engraving Quality Through Experience And Technology FTA InfoFlex BOOTH #232 Drupa 2012 Hall 15, Booth 15; B25 Laser Engraved Ceramic Anilox Service • High definition anilox engravings • Specialty engravings for your custom process laes to h/dloc , s e vis e h da , s gnita o C • application engravings htiw tsis s a o t e civre s lacinh c e T • your specification needs yrts u d ni e ht ni e m it daeltsetr o h S •