Printing as a Means of Paper Testing

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Presented at the Symposium Platte und Papier, Hochschule der Medien, Stuttgart, 2009-10-28

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Printing as a Means of Paper Testing

  1. 1. Printing as a Means of Paper Testing Petter Kolseth
  2. 2. The structure of paper Ink on matt-coated fine paper Ink film thickness of 1-2 µm on ~15 µm coating 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 2
  3. 3. Ink film thickness on coated fine paper Silk Matt 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 3
  4. 4. Runnability in sheet-fed offset Full-scale trial on low-grammage coated 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 4
  5. 5. Different types of print • Newspapers Reproduction of text and • Magazines images to please the reader, advertiser or • Special interest magazines artist • Manuals Expectations • Books Total impression • Art books, coffee table prints Print quality • Corporate communication, Annual reports • Sales promotion • Direct mail • Paper testing Reproduction of technical areas that reveal the potential of the paper 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 5
  6. 6. What should we include in print quality potential? • Print mottle Today’s presentation – back-trap, water-induced, halftone, gloss • Colour gamut • Tone Value Increase • Print evenness – Potential to carry dark and heavily inked images • Ink drying and ink setting • Trapping values 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 6
  7. 7. How to determine print quality potential? • Full-scale print trials – Lab prints are not enough • Controlled print run – Target densities – Standard settings (impression, speed…) – Controlled climate – Standard supplies (inks, plates, blankets…) • Calibrated press – Ink roller settings – Fount roller settings (use FOGRA’s test form!) • Dedicated print layout – Technical areas – No images 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 7
  8. 8. Sheet offset on coated woodfree Standardised Print • Market follow-up on 50 European papers – Paper Type 1 and 2 • Comparison of 10 inks on three papers – Gloss, silk, matt (Type 1 and 2) Gretag Spectrolino Scanning densitometer Print layout 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 8
  9. 9. A print layout for print quality potential: K-C-M-Y-C Print Mottle Print gloss Black Ink scuffing C50 + M50 C80C + M40M Print gloss 400% C100 C100 Ink setting and drying 5th unit No back-trap 2nd unit C100 K40 2nd unit Ink Setting No back-trap No back-trap Tone 400 K40 K K40 Curves B G R Print Evenness Y M C 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 9
  10. 10. Different types of mottled print • Back-trap mottle – Uneven ink films and transparent inks • Water-induced mottle – Uneven ink transfer – Ink refusal where excess fount can’t be accommodated in coating • Paper optics – Halftone mottle – Yule-Nielsen effects in screen tones – Gloss mottle • Ink trap mottle – Uneven trapping of second ink 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 10
  11. 11. Print Mottle Solid Cyan Blue halftones C+M 40% black 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 11
  12. 12. What is back trap? • ’Trapping’ is when ink is transferred to a wet ink film on the paper – (e.g. magenta on cyan) • Back trap is when the wet ink is transferred from the paper to the following blanket – (e.g. cyan onto magenta blanket) • Ideally, an equilibrium ink-film thickness is formed on back-trap blankets • Subsequent ink-film splits in back trap level out the unevenness formed by collapsing ink filaments (higher print density in black after back trap) 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 12
  13. 13. Four-colour offset printing Black ink Cyan ink Magenta ink Yellow ink Blanket to paper Blanket to paper Blanket to paper Blanket to paper Black ink Black ink Black ink Paper to blanket Paper to blanket Paper to blanket Cyan ink Cyan ink Paper to blanket Paper to blanket Magenta ink Paper to blanket 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 13
  14. 14. Five-cylinder configuration with chain transfer systems 0,25 s 2,5 s 0,25 s Y M C K 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 14
  15. 15. Back-trap equilibrium is more easily disturbed for the first inks down 2,00 1,80 equilibrium equilibrium equilibrium Print density 1,60 paper with 1,40 slow ink setting paper with 1,20 slow change to paper with back to paper with paper with ink setting medium ink-setting rate slow ink setting medium ink-setting rate 1,00 paper with Printing order slow ink setting 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 15
  16. 16. Immobilisation of a setting ink film immobilisation front moves upwards through ink film 0,1 s 1s 3s 10 s 30 s 1 min 3 min Ink setting time 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 16
  17. 17. Shift of ink split position after changing to a faster setting paper back-trap ink on last blanket 50% splitting of non- immobilized ink film non-immobilized ink non-immobilized ink 50% immobilized ink immobilized ink paper coating paper coating 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 17
  18. 18. The effect is highly dependent on ink-setting rate 2,20 2,00 Print density 1,80 equilibrium equilibrium equilibrium 1,60 paper with slow 1,40 ink setting paper with paper with 1,20 slow change to paper with back to paper with fast ink setting fast ink-setting rate slow ink setting ink-setting rate 1,00 paper with Printing order slow ink setting 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 18
  19. 19. Print on sheet with uneven ink-setting characteristics sheet with ”slow-setting spots” gets mottled after back-trap 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 19
  20. 20. The memory effect Uneven print also on next sheet ”spotless” sheet gets mottled print due to back-trap 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 20
  21. 21. Water-induced print mottle • Printing on pilot-coated paper • Low coating porosity resulting in unwanted hold-out of fount • Excessive feed of fount in all print units • Ink refusal where coated surface was too wet 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 21
  22. 22. Increasing the fount supply results in white spots in the solid print low fount supply high fount supply Solid areas printed without pre-damp but with back-trap (10 pts SB-latex) 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 22
  23. 23. Back-trap will improve print quality in areas with excessive pre-damp no back-trap with back-trap 70% areas printed with pre-damp (15 pts PVAc-latex) 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 23
  24. 24. Excessive pre-damp may ruin print quality of high binder content coatings no pre-damp with pre-damp 70% areas printed with back-trap (20 pts SB-latex) 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 24
  25. 25. Disturbed ink transfer after excessive fount supply in four printing units burnout Gloss-coated 250 gsm 2nd unit 5th unit 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 25
  26. 26. Disturbed ink transfer after excessive fount supply in four printing units burnout Silk-coated 250 gsm 2nd unit 5th unit 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 26
  27. 27. Mottle in black screen tones • High contrast between black dots and surrounding white paper • Total reflectance is average of unprinted white and (non-reflecting) black dots • Ink film density not very important • Yule-Nielsen shadows in white areas is a major contribution 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 27
  28. 28. Optical dot gain Yule-Nielsen shadows Stefan Gustavson, LiU 1998 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 28
  29. 29. Optical dot gain Effect on tone value and colour AM FM after Matthieu Bossan, Creo, 2002 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 29
  30. 30. Optical dot gain Yule-Nielsen shadows coating base sheet 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 30
  31. 31. Optical dot gain Yule-Nielsen shadows Lost light ray due to lateral light scattering in base sheet 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 31
  32. 32. Halftone mottle correlates to coat weight variations Print mottle in 40% black 2.0 1.8 1.6 Further evidence: SEM images show that 1.4 Dark regions have thin coating (more Yule-Nielsen shadow from 1.2 base paper) 1.0 No significant difference in physical 0.0 2.5 5.0 7.5 (mechanical) tone between dark and Coat-weight variations (burnout test) light regions 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 32
  33. 33. Burn out – Coat weight variations Halftone mottle = 1,51 Coat weight = 18 gsm Halftone mottle = 0,94 Coat weight = 22 gsm 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 33
  34. 34. Ink-trap mottle and more… Blue halftones (Cyan+Magenta) • Blue halftones combine ink-trap mottle and the two basic types of mottle: – the halftone character showing dot gain variation – the transparent ink film showing ink film thickness variation 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 34
  35. 35. Print evenness is important in heavy images Quality index, Fruit 10 8 6 4 2 0 0 2 4 6 8 Print evenness 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 35
  36. 36. Print evenness Gloss mottle – Print gloss homogeneity Mikael Lindstrand, STFI 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 36
  37. 37. Print evenness three different surfaces on a curved sample holder plastic film good WFC poor LWC 1 mm Mikael Lindstrand, STFI 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 37
  38. 38. Print evenness – Surface roughness 5 4 Print evenness 3 2 1 0,40 0,60 0,80 1,00 1,20 1,40 Surface roughness Gloss-Coated 200 – 350 gsm 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 38
  39. 39. Print evenness – Paper gloss 5 4 Print evenness 3 2 1 55 60 65 70 75 80 85 Paper gloss Gloss-Coated 200 – 350 gsm 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 39
  40. 40. Print evenness – Print gloss 400 5 4 Print evenness 3 2 1 75 80 85 90 95 Print gloss 400% Gloss-Coated 200 – 350 gsm 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 40
  41. 41. Paper shade Ludovic Coppel, Innventia Paper shade
  42. 42. Print substrate colour and gloss ISO 12647-2: Offset lithography • Five typical paper types and their shade/colour and gloss: Paper type L* a* b* gloss 1. Gloss-coated, woodfree 93(95) 0(0) -3(-2) 65 2. Matte-coated, woodfree 92(94) 0(0) -3(-2) 38 3. Gloss-coated, web 87(92) -1(0) 3(5) 55 4. Uncoated, white 92(95) 0(0) -3(-2) 6 5. Uncoated, slightly yellowish 88(90) 0(0) 6(9) 6 Tolerance ±3 ±2 ±2 ±5 ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- – Black backing to allow for showthrough from reverse print Values in brackets refer to white backing Substrate backing (white) is standard in paper industry – D50 illuminant, 2° observer, 0/45 or 45/0 geometry D65/10° or C/2° and d/0° geometry is standard in paper industry 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 42
  43. 43. Print substrate used for proofing ISO 12647-2: Offset lithography • Five typical paper types and their shade/colour and gloss: Paper type L* a* b* gloss 1. Gloss-coated, woodfree 93(95) 0(0) -3(-2) 65 2. Matte-coated, woodfree 92(94) 0(0) -3(-2) 38 3. Gloss-coated, web 87(92) -1(0) 3(5) 55 4. Uncoated, white 92(95) 0(0) -3(-2) 6 5. Uncoated, slightly yellowish 88(90) 0(0) 6(9) 6 Tolerance ±3 ±2 ±2 ±5 ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- • Print substrate used for proofing – identical to that of the production • If not possible – close match in colour, gloss, surface grammage • Press proofing on closest match to five typical paper surface types • Proof substrate to conform … to attributes in Table 1 of the paper type representing the production paper 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 43
  44. 44. Paper shade – Elrepho D65/10° Paper Type 1 – 90-250 gsm 0 -1 Measurements according -2 to paper industry -3 standard CIELAB-b* -4 -5 All products out-of-range -6 -7 -8 -9 -10 -5 -4 -3 -2 -1 0 1 2 3 4 5 CIELAB-a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 44
  45. 45. Paper shade – Elrepho D65/10° Paper Type 2 – 90-250 gsm 0 -1 Measurements according -2 to paper industry -3 standard CIELAB-b* -4 -5 All except one products -6 out-of-range -7 -8 -9 -10 -5 -4 -3 -2 -1 0 1 2 3 4 5 CIELAB-a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 45
  46. 46. Paper shade – Elrepho C/2° Paper Type 1 – gloss 90-250 gsm 0 -1 Measurements according -2 to "indoor whiteness" -3 standard CIELAB-b* -4 -5 Some products in the box -6 -7 -8 -9 -10 -5 -4 -3 -2 -1 0 1 2 3 4 5 CIELAB-a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 46
  47. 47. Paper shade – Spectrolino D50/2° Paper Type 1 – 90-250 gsm 0 -1 Measurements according -2 to printing industry -3 standard CIELAB-b* -4 UV content not known -5 Most products in the box -6 -7 -8 -9 -10 -5 -4 -3 -2 -1 0 1 2 3 4 5 CIELAB-a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 47
  48. 48. Paper shade – D65/10° - D50/2° - i1 D50/2° Paper Type 2 – Silk-coated fine paper 20 Moderate fluorescence 15 The D65 UV setting high 10 enough to offset the b* 5 b* 0 -5 -10 -15 D50 i1D50 D65 -20 -20 -15 -10 -5 0 5 10 15 20 a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 48
  49. 49. Paper shade – D65/10° - D50/2° - i1 D50/2° Paper Type 3 – Uncoated fine paper 20 Strong fluorescence 15 The D65 UV setting gives 10 even larger offset in b* 5 b* 0 -5 -10 -15 D50 i1D50 D65 -20 -20 -15 -10 -5 0 5 10 15 20 a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 49
  50. 50. Paper shade – D65/10° - D50/2° - i1 D50/2° Paper Type 4 – Uncoated WoodFree without OBA 20 No fluorescence 15 D65 and D50 quite close, 10 but D50 slightly more red 5 b* 0 -5 -10 -15 D50 i1D50 D65 -20 -20 -15 -10 -5 0 5 10 15 20 a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 50
  51. 51. Conclusions – Paper Shade A matter of taste – forget "ISO compliant" ISO does not specify allowed shades Should be determined with dedicated equipment Most papers are within a narrow range of shades
  52. 52. Primaries and Secondaries Andreas Paul, FOGRA Primaries and Secondaries
  53. 53. Colour gamut – Spectrolino D50/2° Paper Type 1 and 2, gloss/matt/silk 90-250 100 Gloss b* Matt/Silk 80 All prints rather close to Target values 60 target colour CMYRGB 40 Original RGB targets 20 -a* a* 0 -100 -80 -60 -40 -20 0 20 40 60 80 100 -20 -40 -60 -80 -b* -100 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 53
  54. 54. Colour gamut – Spectrolino D50/2° Paper Type 1 and 2, gloss/matt/silk 90-250 100 b* 80 All prints very close to 60 target colour CMYRGB 40 After the 2004 Amendment 20 -a* a* 0 -100 -80 -60 -40 -20 0 20 40 60 80 100 -20 -40 -60 -80 -b* -100 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 54
  55. 55. Ten inks on gloss, silk and matt paper Colour gamut – Elrepho C/2° 100 Ten inks on Gloss paper CIE b* Ten inks on Silk paper 80 Ten inks on Matt paper 30 ink-paper 60 combinations but almost identical results 40 20 CIE -a* 0 CIE a* -100 -80 -60 -40 -20 0 20 40 60 80 100 -20 -40 -60 -80 -100 CIE -b* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 55
  56. 56. Conclusions – Primaries and Secondaries No (or very small) influence of paper brand Target colours can be reached with standard inks
  57. 57. Paper fluorescence Ludovic Coppel, Innventia Paper fluorescence
  58. 58. Fluorescence – CIE Whiteness (D65) 70 60 Fluorescence (D65/10°) 50 40 30 20 10 100 110 120 130 140 150 CIE Whiteness (D65/10°) Gloss-Coated 200 – 350 gsm 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 58
  59. 59. CIE Whiteness – CIELAB-b* (D65) 150 140 CIE Whiteness (D65/10°) 130 120 110 100 -14 -12 -10 -8 -6 -4 -2 0 CIELAB-b* (D65/10°) Gloss-Coated 200 – 350 gsm 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 59
  60. 60. Primaries and Secondaries – Elrepho D65/10° Paper Type 2 – Silk-coated fine paper Elrepho D65/10° 100 80 60 40 b* 20 0 -20 -40 -60 -80 -60 -40 -20 0 20 40 60 80 a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 60
  61. 61. Primaries and Secondaries – i1 D50/2° Paper Type 2 – Silk-coated fine paper 100 80 60 40 b* 20 0 -20 -40 -60 -80 -60 -40 -20 0 20 40 60 80 a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 61
  62. 62. Primaries and Secondaries – D50/2° Paper Type 2 – Silk-coated fine paper Elrepho D50/2° 100 80 60 40 b* 20 0 -20 -40 -60 -80 -60 -40 -20 0 20 40 60 80 a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 62
  63. 63. Primaries and Secondaries – D50/2° UV excluded Paper Type 2 – Silk-coated fine paper Elrepho D50/2° UV excluded 100 80 60 40 b* 20 0 -20 -40 -60 -80 -60 -40 -20 0 20 40 60 80 a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 63
  64. 64. Spectral power and Relative UV content Illuminants D65, C, D50, A Relative to 560 nm (max colour vision) Relative to 440 nm fluorescence peak 300 2,00 1,75 250 1,50 Spectral Power 200 Spectral Power 1,25 150 1,00 0,75 100 0,50 50 0,25 0 0,00 350 400 450 500 550 600 650 700 750 340 360 380 400 420 440 460 480 500 520 540 560 Wavelength, nm Wavelength, nm D65 C D50 A D65rel Crel D50rel Arel Relative power of A is almost twice that of C between 340 and 380 nm 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 64
  65. 65. Illumination is NOT same as Illuminant Illumination 5000K and Illuminant D50 D50 2 D65 5000K CCT 5000K CCT + UV Relative Power 1,5 1 0,5 0 300 350 400 450 500 550 600 650 700 750 Wavelength (nm) Ludovic Coppel, Innventia, 2008 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 65
  66. 66. Proof substrates from one supplier x-rite iOne – a*-b* data 6,0 Red symbols denote 4,0 certified proof substrates 2,0 Green symbols denote production 0,0 paper PT2 and PT4 CIELAB-b* -2,0 Type 2 -4,0 -6,0 Type 4 -8,0 -10,0 -12,0 -14,0 -2,0 -1,5 -1,0 -0,5 0,0 0,5 1,0 1,5 2,0 2,5 3,0 CIELAB-a* 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 66
  67. 67. Conclusions – Paper Fluorescence Fluorescence make papers whiter (more blue) Effect is very dependent on illumination Fluorescence shines through all print Matching proof to print with proper choice of proof substrate and illumination
  68. 68. Tone Value Increase Tone Value Increase
  69. 69. Tone Value Increase: Black and Cyan Paper Type 1 – 90-250 gsm 30% 30% 25% 25% Black Tone Value Increase Cyan Tone Value Increase 20% 20% +/- 4 20% 20% +/- 4 15% 15% 10% 10% 5% 5% 0% 0% 0% 20% 40% 60% 80% 100% 0% 20% 40% 60% 80% 100% Nominal tone Nominal tone Black and Cyan Dot Gain are both within tolerance 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 69
  70. 70. Optical dot gain Effect on tone value and colour AM FM after Matthieu Bossan, Creo, 2002 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 70
  71. 71. Reflectance histograms of K100, K40 and paper white 13,2% TVI(40) 2,5 25,0 2,0 20,0 Frequency, % 1,5 15,0 1,0 10,0 0,5 5,0 0,0 0,0 0 20 40 60 80 100 Reflectance, % <K40> <BLACK> <WHITE> 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 71
  72. 72. Reflectance histograms of K100, K40 and paper white 20,1% TVI(40) 2,5 25,0 2,0 20,0 Frequency, % 1,5 15,0 1,0 10,0 0,5 5,0 0,0 0,0 0 20 40 60 80 100 Reflectance, % <K40> <BLACK> <WHITE> 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 72
  73. 73. Reflectance histograms of K100, K40 and paper white 13,2% TVI(40) 2,5 25,0 Halftone dots Between dots 2,0 20,0 Frequency, % 1,5 15,0 Unimaged Solid black paper 1,0 10,0 0,5 5,0 0,0 0,0 0 20 40 60 80 100 Reflectance, % <K40> <BLACK> <WHITE> 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 73
  74. 74. Reflectance histograms of K100, K40 and paper white 20,1% TVI(40) 2,5 25,0 Halftone dots 2,0 20,0 Unimaged Frequency, % paper 1,5 15,0 Between Solid black dots 1,0 10,0 0,5 5,0 0,0 0,0 0 20 40 60 80 100 Reflectance, % <K40> <BLACK> <WHITE> 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 74
  75. 75. Black halftone seen in the microscope 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 75
  76. 76. Thresholding between peaks in histogram 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 76
  77. 77. Tone Value comparison Densitometer readings vs. microscopy 56 Microscopy Tone Value 54 52 50 48 46 50 52 54 56 58 60 62 64 Densitometer Tone Value 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 77
  78. 78. Optical Tone Value Increase Tone Values by microscopy 10,0 Single-coat matt 8,0 Optical TVI multicoat 6,0 gloss multicoat silk 4,0 2,0 0,0 -20 -15 -10 -5 0 Reduction in paper reflectance between dots 28 Octoberl 2009 Printing for Paper Testing / Petter Kolseth 78
  79. 79. Conclusions – Tone Value Increase Mechanical TVI is small (in the ideal case) Optical TVI is quite large Optical TVI is an inherent paper property (but not related to brand) TVI variations are mechanical due to press settings
  80. 80. Stay in control…

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