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Paper, the Fifth Color Current Classifications Optical Brighteners By Trish Wales Sappi Fine Paper March 15,2006 April 9, 2006
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First Segmentation U.S. vs. EU Coated Supercalendered Newsprint Uncoated Coated Supercalendered Newsprint Uncoated
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U.S. Coated Paper Classification ClassificationBrightness [Tappi T452] Premium94+ No. 1 Coated91-94 No. 2 Coated87-91 No. 3 Coated82-87 No. 4 Coated75-82 No 5 Coated ]N/A Coated Free Sheet Classification ClassificationBrightness [Tappi T452} PremiumN/A No. 1 CoatedN/A No. 2 Coated87+ No. 3 Coated82-87 No. 4 Coated75-82 No. 5 CoatedUnder 75 Coated Groundwood Classification
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Supercalendered Classification GE Brightness75 0 Gloss SC-A++> 73> low 50's SC-A+70-72High 40's - low 50's SC-A67-69High 30's - low 40's SC-B64-66Low 30's SC-C60-64Low 30's or <
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Uncoated Paper Classification Quality and Use –Offset Utility Opaque Premium Opaque Copy Paper –Text and cover Writing Papers Bristols –Newsprint Finish –Smooth –Vellum –Embossed Laid Wove
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Brightness
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Paper Ink Film Illuminant Brightness is measured at one wave length 457 nm Brightness
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Test Methods BrightnessTAPPI - Paper (GE Brightness) ISO - Paper Standard IDTAPPI T452ISO 2469, 2470 GeometryDirectionalDiffuse IlluminantCD65 [C]
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Test Comparison
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European Classification Related to paper manufacturing process Separated by fiber type Number of coating layers considered
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European Papers Chemical Pulp Mechanical Pulp Art Std WFC UWF Std. LWC HWC MWC FCO MFC SC Newsprint Relative Quality Relative Price
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ISO 12647-2 Five types Optical characterization Shade/Gloss
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ISO 12647-2 Categories 1. Gloss Coated, woodfree 2. Matte Coated, woodfree 3. Gloss Coated, web 4. Uncoated, white 5. Uncoated, slightly yellowish
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Paper Types Type L* Black L* White a* Black a* White b* Black b* White Gloss/ ISO BRT 1939500-3-265/89 2929400-3-238/89 3879203555/70 4929500-3-26/93 5889000696/73 Toler ance +/-3 +/-2 +/-5
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Fluorescence
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Optical Brighteners Prevalent Increasing Measurement nightmare Visual Matching challenge
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What are they? Chemical additives –Textiles –Paints –Paper
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Paper OBA Properties Absorb light in UV More UV, more absorbed, more emitted Emit in blue region No UV, no emission Unstable in light –Paper goes from white to yellow
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Optical Brighteners Absorption 300 Wavelength in nm 350400450500550600650700 -100 -50 0 50 100 Re-Emission
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OBA affects Print See effect in the white spaces See effect through cyan ink Effect blocked by magenta and black ink Yellow ink effect depends on ink transparency On-line measurements give false reading –Pulsed Xenon –White point compensation
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Optical Brighteners
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Questions????
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