Iarigai 2009 Printing By The Numbers

Printing by the numbers
Petter Kolseth
Luc Lanat, Örjan Sävborg
Stora Enso
Sweden & France
petter.i.kolseth@storaenso.com
www.storaenso.com

36th International Research Conference
Stockholm, Sweden

Printing by the numbers on commercial paper
Petter Kolseth, Luc Lanat, Örjan Sävborg

Standardised Print

September 2009 Printing by the numbers / Kolseth-Lanat-Sävborg 3

Standardised Print

So where was the Paper Industry…?


Standardised Print – Why Now?

• Fogra offset process standards
date back to the 1980’s
• ISO 12647-2 appeared first in 1996
• Paper sales was approached by printers only over last couple of years

• Print is moving towards an industrial process


Potential sources for confusion and debate

• "Numbers" in the ISO standards
– Paper shade
– Primary and secondary colours
– Tone Value Increase – tonal transfer

• Measurement conditions and calibration procedures
– Paper industry: D65/10°, C/2°, D50/2°
– Graphic industry: M0, M1, M2, M3

• Paper fluorescence


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


Ludovic Coppel, Innventia

Paper shade

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

Print substrate used for proofing
ISO 12647-2: Offset lithography

• 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

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

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

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*


Paper shade – Elrepho D65/10°

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*


Paper shade – Elrepho C/2°
Paper Type 1 – gloss 90-250 gsm

0

-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*


Paper shade – Spectrolino D50/2°

0

-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*


Shades of double-coated glossy papers
More than 80% would fit into a proposed new recommended range
0,00

-1,00

-2,00

-3,00
CIELAB-b*

-4,00

-5,00

-6,00

-7,00

-8,00

-9,00
0,00 0,50 1,00 1,50 2,00 2,50
CIELAB-a*

Presentation WG3TF1 Paper Characterization (Bertholdt, ISO TC130 WG3, Bangkok 2007-05-15)


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*


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*


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*


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

Andreas Paul, FOGRA

Primaries and Secondaries

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


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


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*


Conclusions – Primaries and Secondaries

No (or very small) influence of paper brand

Target colours can be reached with standard inks

Ludovic Coppel, Innventia

Paper fluorescence

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


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


Primaries and Secondaries – Elrepho D65/10°
Elrepho D65/10°
100

80

60

40
b*

20

0

-20

-40

-60
-80 -60 -40 -20 0 20 40 60 80
a*


Primaries and Secondaries – i1 D50/2°

100

80

60

40
b*

20

0

-20

-40

-60
-80 -60 -40 -20 0 20 40 60 80
a*


Primaries and Secondaries – D50/2°
Elrepho D50/2°
100

80

60

40
b*

20

0

-20

-40

-60
-80 -60 -40 -20 0 20 40 60 80
a*


Primaries and Secondaries – D50/2° UV excluded
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*


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


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


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*


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

Tone Value Increase: Black and Cyan

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


Optical dot gain
Effect on tone value and colour

AM

FM

after Matthieu Bossan, Creo, 2002


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>


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, %



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, %



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, %



Black halftone seen in the microscope


Thresholding between peaks in histogram


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


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


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

What is next?

Luc LANAT Stora Enso PrintNet at iarigai Stockholm Sept 2009

Optics – What next?

• To define (White) Paper shade targets
– Use ISO 5631-1 or 2 Colour L*a*b* C/2° or D65/10°

• ISO 13655-2009 must not be used to specify (white) papers
– Use ISO 5631-3 Colour L*a*b* D50/2°

• To evaluate Fluorescence in papers
– Use ISO 2470-2 (Note 8.4) on D65 Brightness
– Use ISO 11476 (Note 10.3), ISO 11475 (Clause 10.3). Whiteness

• Organize UV calibration of D50 illuminant is a MUST


Dot Gain – TVI

• ISO TS 10128-2008 « Methods of adjustment of the colour reproduction
of a printing system to match a set of characterisation data »

– When measuring quality of a print thru reflectance, you are indeed
integrating all variations, variations coming from base, thus paper,
variations coming from inks, from press, etc…

– To define Dot Gain or TVI of a paper is a misunderstanding


Standardization – What next?

• There is no ISO compliant paper
– See Paperdam statement Sept 2009
– We recommend publicly available colour profiles and
characterization data (ECI, PSR, FOGRA…)

• ISO TC 6 Berlin, support creation of NWI
– Develop ISO 5630-7, aging under light conditions to evaluate light
fastness
– Develop D 50 UV calibration rules

• ISO TC 130 Beijing, support creation of NWI
– How to measure proof papers
– JWG (joint working group) liaison TC 6 – TC 130


The last slide – 3 points

• The daily challenge in a paper mill is to fulfil paper specifications
communicated in Technical Data Sheets, in this order
– Brightness and shade
– Smoothness (PPS,…)
– Gloss
– Anything to satisfy printing results at printer

• Process Management at printer and at papermaker is the topic
– For a given grade, work on process consistency and not on
upgrade of paper definition to reach better printed results

• It is common interest of all players in this market to help standardization
and support quality of printed media at lowest cost


Iarigai 2009 Printing By The Numbers

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Iarigai 2009 Printing By The Numbers