Minimization of Metamerism in Wood Grain Printing using ...

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Master's Theses Graduate College

6-2016

Minimization of Metamerism in Wood Grain Printing using Minimization of Metamerism in Wood Grain Printing using

Different GCR Settings Different GCR Settings

Vinay Anil Turke

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MINIMIZATION OF METAMERISM IN WOOD GRAIN PRINTING

USING DIFFERENT GCR SETTINGS

by

Vinay Anil Turke

A thesis submitted to the Graduate College

in partial fulfillment of the requirements

for the Degree of Master of Science

Chemical and Paper Engineering

Western Michigan University

June 2016

Thesis Committee:

Dr. Paul D. Fleming, Ph.D., Chair

Dr. Alexandra Pekarovicova, Ph.D.

Dr. Veronika Husovska, Ph.D.

MINIMIZATION OF METAMERISM IN WOOD GRAIN

PRINTING USING DIFFERENT GCR SETTINGS

Vinay Anil Turke, M.S.

Western Michigan University, 2016

In printing industry, prototyping is necessary to ensure quality

reproduction of jobs. Conventional printing processes like gravure cannot be used

for prototyping because of high manufacturing cost of gravure cylinders. Such

challenges can be successfully tackled by use of relatively cheap and flexible

printing processes, such as inkjet. Even though inkjet printing is a cost effective

way for prototyping, it has its own limitations, especially in the case of wood-

grain printing. Wood-grain patterns need to be printed with a release coating and

adhesive. Inkjet printers are incapable of printing release coating and adhesive

because release coat and adhesive require certain amount of coat weight, which is

not possible with inkjet printing. Inaccurate color reproduction, metamerism and

incompatibility with release coat are the commonly seen problems during

prototyping. The main aim of study was to resolve problems of metamerism and

achieve close color match. A Design of Experiments (DOE) was carried out by

using different factors such as gray component replacement (GCR) settings,

release coat weight and use of tie coat to analyze its effect on metamerism.

Results showed that GCR setting was the most influential factor among all

factors.

Copyright by

Vinay Anil Turke

2016

ii

ACKNOWLEDGMENTS

I would like to thank Western Michigan University for providing me such a

wonderful opportunity to pursue my career in the Paper and Printing Science program. In

addition, I would like to thank the Department of Chemical and Paper Engineering for

providing me necessary facilities and help for the completion of the thesis.

I would like to express my humble gratitude to my thesis committee chair Prof.

Dr. Paul D Fleming who continuously helped me in my thesis and master’s program.

His knowledge, dedication and kindness inspired me a lot in my academic and personal

life as well.

I also want to thank my thesis committee members Prof. Prof. Dr. Alexandra

Pekarovicova and Dr. Veronika Husovska for their valuable advice and encouragement

throughout the thesis.

I would like to give my sincere thanks to Mr. Adelbert Bell and my all ProEdge

Inc. colleagues for providing me necessary equipment and support for the completion of

the project.

Most importantly, I would like thank my mother Mrs. Varsha Turke for

everything she has done for me at every stage of my life. In addition, I want to thank my

uncle Mr. Prakash Turke who always stood behind me as a fatherly figure and inspired

me to continue family legacy by perusing career in printing industry. I want thank all my

family members for supporting me through this journey.

iii

Acknowledgments – continued

Finally, I must express my very profound gratitude to Mr. Shreyas Pradeep

Pathak who stood by me as a real friend during all difficulties of my life.

Vinay Anil Turke

iv

TABLE OF CONTENTS

ACKNOWLEDGMENTS .................................................................................................. ii

LIST OF TABLES ............................................................................................................. vi

LIST OF FIGURES .......................................................................................................... vii

CHAPTER .......................................................................................................................... 1

I. LITERATURE REVIEW ................................................................................................ 1

Printing Processes ..................................................................................................... 1

Gravure Printing .............................................................................................. 1

Inkjet Printing .................................................................................................. 3

Chemistry of Printing Inks ........................................................................................ 7

Gravure Inks .................................................................................................. 11

Inkjet Inks ...................................................................................................... 12

Essential Color Management Concepts .................................................................. 15

Metamerism ................................................................................................... 15

Metamerism Index ......................................................................................... 16

UCR and GCR ............................................................................................... 18

II. PROBLEM STATEMENT .......................................................................................... 20

III. EXPERIMENTAL ...................................................................................................... 22

Phase-I ..................................................................................................................... 22

Phase-II ................................................................................................................... 23

Selection Criteria of Factors for Design of Experiments ........................................ 25

v

Table of Contents – Continued

CHAPTER

IV. RESULTS AND DISCUSSION ................................................................................. 28

Phase-I ..................................................................................................................... 28

Effect of Customized ICC Profile and Manual GCR Adjustment on ∆E ...... 28

Effect of Customized ICC Profile and Manual GCR Adjustment on

Metamerism Index ......................................................................................... 30

Effect of Customized ICC Profile and Manual GCR Adjustment on

Spectral Curves ............................................................................................. 32

Phase-II ................................................................................................................... 35

Effect of GCR Settings on ∆E and Metamerism Index ................................. 36

Effect of GCR Settings on Spectral Curve Distribution ................................ 45

Effect of Color Gamut Volume on Metamerism Index ................................. 54

Design of Experiments Analysis ................................................................... 57

CONCLUSION ................................................................................................................. 62

BIBLIOGRAPHY ............................................................................................................. 64

APPENDICES .................................................................................................................. 68

vi

LIST OF TABLES

1: Trials for Design of Experiments .................................................................. 24

2: Analysis of Variance (ANOVA) for Smooth Grey. ...................................... 58

3: Analysis of Variance (ANOVA) for Hunter 655. .......................................... 58

4: Analysis of Variance (ANOVA) for Galaxy Oak. ......................................... 59

5: Analysis of Variance (ANOVA) for Rustic Maple. ...................................... 59

vii

LIST OF FIGURES

1. Basic Schematic of Gravure Printing Process (4) ............................................... 2

2. Overview of Inkjet Printing Process (7) ............................................................. 4

3. Continuous Inkjet Printing Process (7) ............................................................... 5

4. Thermal(A), Piezoelectric(B) and Electrostatic(C) drop on demand inkjet (7) .. 6

5. Sample Patches, with CIE LAB values............................................................. 23

6. Schematic of Wood Grain Layers. .................................................................... 25

7. Galaxy Oak: Phase-I ∆E Comparison. .............................................................. 28

8. Smooth Grey: Phase-I ∆E Comparison............................................................. 29

9. Hunter 655 Phase-I ∆E Comparison. ................................................................ 29

10. Rustic Maple Phase-I ∆E Comparison. ........................................................... 30

11. Galaxy Oak Phase-I Metamerism Index. ........................................................ 31

12. Smooth Grey Phase-I Metamerism Index. ...................................................... 31

13. Hunter 655 Phase-I Metamerism Index. ......................................................... 32

14. Rustic Maple: Phase-I Metamerism Index. ..................................................... 32

15. Galaxy Oak Phase-I Spectral Curve Comparison. .......................................... 33

16. Smooth Grey Phase-I Spectral Curve Comparison. ........................................ 34

17. Hunter 655 Phase-I Spectral Curve Comparison. ........................................... 34

18. Rustic Maple Phase-I Spectral Curve Comparison. ........................................ 35

19. Galaxy Oak 7g/m2 Release Coat + Tie Coat ∆E & Metamerism Index. ........ 37

20. Smooth Grey 7g/m2 Release Coat + Tie Coat ∆E & Metamerism Index. ...... 37

21. Hunter 655 7g/m2 Release Coat + Tie Coat ∆E & Metamerism Index. ......... 38

viii

List of Figures – Continued

22. Rustic Maple 7g/m2 Release Coat + Tie Coat ∆E & Metamerism Index. ...... 38

23. Galaxy Oak 7g/m2 Release Coat only ∆E & Metamerism Index. .................. 39

24. Smooth Grey 7g/m2 Release Coat only ∆E & Metamerism Index. ................ 39

25. Hunter 655 7g/m2 Release Coat only ∆E & Metamerism Index. ................... 40

26. Rustic Maple 7g/m2 Release Coat only ∆E & Metamerism Index. ................ 40

27. Galaxy Oak 10.5 g/m2 Release Coat + Tie Coat ∆E & Metamerism Index. .. 41

28. Smooth Grey 10.5 g/m2 Release Coat + Tie Coat ∆E & Metamerism Index. 41

29. Hunter 655 10.5 g/m2 Release Coat + Tie Coat ∆E & Metamerism Index. ... 42

30. Rustic Maple 10.5 g/m2 Release Coat + Tie Coat ∆E & Metamerism Index. 42

31. Galaxy Oak 10.5 g/m2 Release Coat only ∆E & Metamerism Index. ............ 43

32. Smooth Grey 10.5 g/m2 Release Coat only ∆E & Metamerism Index. .......... 43

33. Hunter 655 10.5 g/m2 Release Coat only ∆E & Metamerism Index. ............. 44

34. Rustic Maple 10.5 g/m2 Release Coat only ∆E & Metamerism Index. .......... 44

35. Spectral Curve 7g/m2 plus Tie Coat- Galaxy Oak. ......................................... 46

36. Spectral Curve 7g/m2 plus Tie Coat- Smooth Grey. ....................................... 46

37. Spectral Curve 7g/m2 plus Tie Coat- Hunter 655. .......................................... 47

38. Spectral Curve 7g/m2 plus Tie Coat- Rustic Maple. ....................................... 47

39. Spectral Curve 7g/m2 Release Coat only- Galaxy Oak. ................................. 48

40. Spectral Curve 7g/m2 Release Coat only- Smooth Grey. ............................... 48

41. Spectral Curve 7g/m2 Release Coat only-Hunter 655..................................... 49

42. Spectral Curve 7g/m2 Release Coat only- Rustic Maple. ............................... 49

43. Spectral Curve 10.5 g/m2 plus Tie Coat- Galaxy Oak. ................................... 50

ix

List of Figures – Continued

44. Spectral Curve 10.5 g/m2 plus Tie Coat- Smooth Grey. ................................. 50

45. Spectral Curve 10.5 g/m2 plus Tie Coat- Hunter 655. .................................... 51

46. Spectral Curve 10.5 g/m2 plus Tie Coat- Rustic Maple. ................................. 51

47. Spectral Curve 10.5 g/m2 Release Coat only- Galaxy Oak. ............................ 52

48. Spectral Curve 10.5 g/m2 Release Coat only - Smooth Grey.......................... 52

49. Spectral Curve 10.5 g/m2 Release Coat only - Hunter 655. ............................ 53

50. Spectral Curve 10.5 g/m2 Release Coat only- Rustic Maple. .......................... 53

51. Gamut Volume Comparison ........................................................................... 54

52. Metamerism Index vs. Color Gamut Volume- Galaxy Oak ........................... 55

53. Metamerism Index vs. Color Gamut Volume- Smooth Grey ......................... 55

54. Metamerism Index vs. Color Gamut Volume- Hunter655 ............................. 56

55. Metamerism Index vs. Color Gamut Volume- Rustic Maple ......................... 56

56. Main Effect Plot- Smooth Grey. ..................................................................... 60

57. Main Effect Plot- Hunter 655. ........................................................................ 60

58. Main Effect Plot- Galaxy Oak. ....................................................................... 61

59. Main Effect Plot- Rustic Maple. ..................................................................... 61

1

CHAPTER I

LITERATURE REVIEW

Printing Processes

Gravure Printing

Gravure printing is one of the important printing processes in the graphics

communication industry and occupies 10-15% share of market in industrialized

countries (1). It was developed from the Intaglio printing process and has its

presence since early 15th century. The first intaglio plate was made in Germany in

1446 during the renaissance (2). Later, various versions of plates were developed

but weren’t successful due to incompatibility with Gutenberg`s press.

Simplicity and comparatively fewer set up parameters make gravure

printing a more controllable process among other printing processes, but its costly

image carrier manufacturing limits it only for long run jobs. However, the modern

gravure industry has come up with narrow presses technology, with cheaper

image carriers (3). There are four basic components of gravure printing process

shown in Figure 1.

2

Figure 1: Basic Schematic of Gravure Printing Process (4)

a) Gravure Image carrier: This is the most important component of the

process on which the image area is engraved. A gravure cylinder consists

of a steel base with steel journals, which are covered by copper in multiple

layers based on the type of gravure cylinder. The actual image is engraved

into copper and is plated with a protective chrome layer to reduce wearing

of the cylinder surface from the doctor blade. The image can be engraved

on the cylinder by various methods, such as etching, electromechanical

engraving or direct or indirect laser engraving into a black mask followed

by chemical etching. Laser engraved cylinders give the possibility to

engrave various shapes of cells with differing aspect ratio compared to the

electromechanical engraving process, where the aspect ratio is

predetermined by the geometry of the engraving diamond stylus (5).

b) Doctor Blade: The main function of the doctor blade is to remove

excessive ink from the gravure cylinder surface. It is believed that the

3

doctor blade name evolved from the blade that was used in the letterpress

printing process in association with a “ductor” blade. It can be made from

different materials, such as steel or plastic. Mostly in gravure, steel doctor

blades of 0.004 to 0.015" are used (6). The doctor blade angle, pressure

and material type has a huge impact on printability, as well as on

runnability of the gravure process. The doctor blade angle, which is also

called the blade contact angle, is usually between 55° and 65° (6).

c) Inking Unit: The gravure cylinder rotates in the ink pan and picks up

gravure ink in the engraved cells and carries it to the substrate. A

continuous supply of ink is provided to the ink pan by a pumping system

and is controlled depending on speed of the printing press.

d) Impression roller: The main function of the impression roller is to ensure

controlled transfer of ink onto the substrate. Generally, impression rollers

are made up of rubber or elastomer coated steel rollers.

Inkjet Printing

It is one of the most rapidly developing printing processes. As it does

not have any image carrier, and the print head is located above the print

substrate, it falls under the category of non-impact printing processes. Inkjet

processes can be of various types, but they are mainly divided into two

categories based on their drop formation. ‘Continuous inkjet’ and ‘Drop on

demand’ are two types of inkjet printing processes. Figure 2 shows an

overview of different types of inkjet printing processes.

4

Figure 2: Overview of Inkjet Printing Process (7)

In continuous ink jet printing a continuous stream of droplets is

created and jetted towards the substrate (Figure 3). Image forming droplets

fall on the substrate, while non-image forming dots are deflected, collected

into the gutter, filtered and recycled. Continuous ink jet can be divided into

two sub-types, binary deflection and multi-deflection. In binary deflection

droplets that are supposed to print are uncharged, while non-image forming

droplets are charged for deflection in an electric field. In multi-deflection, dots

receive different charges so as they pass through the electric field and they get

deflected based on their position (7).

5

Figure 3: Continuous Inkjet Printing Process (7)

In drop on demand inkjet printing, droplets are formed only if they are

required. This process can be subcategorized into three types based on the

way of droplet formation. DOD-thermal, DOD-piezo and DOD-electrostatic

are three types of drop on demand inkjet printing processes. In thermal DOD

inkjet, droplets are formed by evaporating liquid, creating bubbles that force

ink through a nozzle to form droplets. In piezo inkjet, droplets are made due to

mechanical movement of a piezoelectric ceramic membrane. Mechanical

movement of a piezoelectric membrane is controlled by the electric controller.

In electrostatic DOD inkjet, an electric field exists between substrate and print

nozzle. The droplets are formed by changing surface tension ratios between

the ink and the nozzle. Droplets are results of field forces (7). Figures 4 A, B

and C show thermal, piezo and electrostatic drop on demand inkjet printing

processes, respectively.

6

Figure 4: Thermal (A), Piezoelectric (B) and Electrostatic (C) Drop on Demand

Inkjet (7)

A

B

C

7

Chemistry of Printing Inks

Printing inks are an integral part of all printing processes and have been so

for a very long time. Writing inks were made in Egypt, as well as in China, in

2500 B.C., but the 1st printing ink was made in China almost 3000 years later

using carbon black pigment, which is today known as a lamp black. Pigmented

inks using synthetic organic pigments were made in 1772, whereas printing inks

with dyes were developed in 19th century (8).

Components of printing inks can be roughly divided into four groups:

A) Colorants

The basic role of colorants is to give color to the ink, but at the

same time, they provide other essential properties to ink, such as opacity,

or transparency. Colorants can be mainly of two types:

a) Pigments: They can be of particle size of 1-2 µm, although usually

less than 400 nm (9), and have a tendency to agglomerate, so they

must be held in suspension by various dispersants (10). About 10%

of pigments are present in ink films on the surface. They have

smaller color intensity as compared to dyes, but pigments have

very good light fastness in comparison with dyes. Specialty

pigments can be used as opacifiers or as an extender. Extenders are

made of various clays, calcium carbonate or silica, and are

generally used to reduce color strength of an ink. When looking at

the gravure inks, formulation of gravure ink contains 50-70% of

solvent, so the selected pigment should have good resistance to

8

solvents and should not have any negative effect on flow

characteristics. Pigments also fulfill some other additional

requirements, such as impart gloss, ink rheology, lightfastness and

tinctorial strength. For organic pigments at normal press viscosity,

pigmentation should not exceed 15%. On the contrary, for

inorganic pigments, 25-35% of pigmentation is common,

especially for TiO2, where high opacity is required (12).

b) Dyes: Dye molecules are dissolved by solvent, therefore every

molecule has a higher tendency to absorb photons and hence

possess higher color intensity than pigments, but lack in providing

light fastness due to UV instability.

B) Resins

a) They are also known as binders. Resins form ink film and bond to

the substrate. Besides that, they impart other functional properties,

such as ink flow, flexibility or toughness, gloss, resistance to

water, chemicals and heat. Pigments are homogenously dispersed

in resin vehicles and are enclosed by dispersants that avoid

pigment agglomeration and cluster formation. The most commonly

used resins are acrylics, alkyds, styrene acrylics, urethanes,

derivatives of cellulose, maleic, etc. It is practically difficult to

identify a sole resin that will fulfill all requirements of an ink.

Hence, an ink is formulated using combinations of two or three

9

resins. Requirements of resins vary by product, but they should

possess some basic characteristics, such as sufficient adhesion,

good solubility in solvent, tack free ink film, good rub resistance

and flexibility. Based on end use application, they should have

secondary properties, such as no odor, resistance to soap or alkali,

etc.

C) Solvents

a) Solvents play an important role in maintaining fluidity of the ink,

so that the ink can be transferred to the substrate. Different printing

processes require different amounts of solvent in their inks. Most

of the time, solvent gets separated from an ink by means various

drying and curing methods after transfer of ink film to the substrate

occurs. Solvent requirements are different for different printing

processes. Rotogravure and flexography require volatile solvents

(Boiling point below 120oC). On the contrary, offset printing

requires high boiling point (240°C to 320°C) hydrocarbon

solvents. Screen printing inks go with moderately high boiling

point solvents (8). Selection of a solvent is dependent on end use

and type of a substrate. For example, in food packaging

applications the solvent used should be odorless after drying. Most

common solvents, which create odorless ink films are ethanol,

isopropanol, ethyl acetate, isopropyl acetate, acetone, methyl ethyl

10

ketone etc. Other commonly used solvents are xylene and toluene,

but those have hazardous effects, thus they should be handled with

care. One more consideration, which should be taken in to account

while selecting solvent, is that it should offer excellent doctor

blade lubrication to avoid engraved cell wall wear due to cylinder

doctoring.

D) Additives

a) Like solvents, additives selected for an ink are dependent on the

type of printing process to provide properties such as drying, flow

and ink film plasticity. Additives not only enhance the runnability

properties, but also improve some other end use properties, such as

rub resistance, coefficient of friction, etc. Waxes, plasticizer,

chelating agents, antioxidants, surfactants and defoamers are some

common additives used in printing inks. Additives in inks

improves overall performance of an ink from printability and

runnability points of view. Some additives are required to perform

during initial manufacturing of an ink, such as enhancing pigment

wetting, and on the other hand, some additives should be added to

improve end properties, such as addition of plasticizers to impart

additional flexibility to an ink film. The type of ink system, such as

solvent based or water based, also affects the selection of additives.

11

In waterborne inks, surfactants are added to reduce the high

surface tension of water and improve wettability of the substrate.

Gravure Inks

Typical gravure ink formulations contain 8-15% pigments, along with

extenders, 15-20% resins, 60-70% solvent, and 0.5-5% additives (11).

Formulation and performance characteristics of an ink are dependent on the type

of printing process. Like flexography, gravure inks are also fluid. Viscosity, flow

and rheology are a few important factors that should be considered before

formulating gravure ink in order to ensure runnability on a press.

Viscosity

The viscosity, determined as efflux time for gravure inks is generally kept

between 15 and 25 s for a Zahn cup #2 at 25oC (12). The viscosity range is highly

dependent on other influencing factors such as, ink rheology, rate of drying

(evaporation), printing speed, gravure cylinder cell shape and depth, doctor blade

type and profile and type of substrate. To ensure good printability, the viscosity

range should be within the specified range. Too high of viscosity might affect the

flow of ink from cells to substrate creating a pattern that is commonly known as

‘screening’. On the other hand, ‘Halo or slurring problems’ are results of too low

of viscosity (12).

12

To achieve fine printing quality, ink laydown on the substrate is crucial.

As ink is transferred from engraved cells onto the substrate, the flow of the ink

plays an important role. To ensure good laydown, gravure ink needs to change

from low viscosity ink to solid matter within fractions of seconds. Solvent

evaporation rate and tack-free attending level of resin play a critical role in it.

After evaporation of solvent, resins bind colorants to the substrate whereas

pigments provide colors. There are other supplementary factors that also influence

flow and rheology to make sure good printing quality that includes doctor blade

pressure and angle, impression roller shore hardness and pressure and type of

engraving.

Inkjet Inks

The basis for inkjet technology is earlier work of Lord Rayleigh in modeling

instability of a capillary jet formation, where excitation of a jet is done by

destabilization to form ink droplets (13). Inkjet inks can be divided into three

main categories; aqueous, non-aqueous and hot melt. A typical aqueous inkjet ink

has 2-8% colorant, 35-80% carrier (vehicle), 0.1-2.0% surfactants, 10-30%

humectant, 1-5% penetrant, 2-5% dye solubilizer and 20-50% additives based on

the type of inkjet process and substrate (14).

A) Physical properties of inkjet inks

In inkjet printing, good dot formation is based on formation of

spherical droplets of equal size, spacing and shape. Poor dot formation

results from ‘satellites’, i.e. tail like appearance to the end of the drop due

to improper splitting of droplets. Properties such as ink viscosity, surface

13

tension, nozzle size, jet velocity, pressure and temperature play very

significant roles in drop formation. Those physical properties change

depending on the type of ink. For example, inkjet inks can be formulated

over a wide range of surface tensions (22-45 mN/m), but for solvent based

inks, surface tension is strictly kept between 25 to 30 mN/m with a

tolerance of ± 3 mN/m (13).

B) Components of Inkjet Inks

a) Colorants: Inkjet ink can be designed using either dyes or

pigments, but each has its own advantages and disadvantages.

Pigmented inks can be made < 1 µm in size, typically being around

100 nm (15) (16). Pigments must be suspended in homogenous

mixtures of solvent/resin suspensions, otherwise pigment particles

are prone to agglomeration. Inherently, some of the pigments are

of abrasive nature, so it is comparatively hard to achieve particle

size and homogenous stability for pigments over dyes, but

pigments provide good light fastness over dyes (15) (16). On the

other hand, dyes exhibit good solubility, more saturated colors and

low impurities, but have poor lightfastness and waterfastness.

b) Solvents: They provide homogenous suspensions to colorants in

the ink, as well as work as solvents to carry pigments. The type of

solvent has a great impact on drying rate of an ink. In order to

achieve good printability, drying rate of a solvent should be

controlled. If the ink has excessive amount of a fast drying solvent,

14

it might cause skin formation or nozzle clogging, but if it is too

slow drying, then it could impact printing speed and introduce new

printing defects, such as smudging. Commonly used solvents are

methyl ethyl ketone (MEK), acetates, ketones, alcohols and glycol

ethers. Volatility of a solvent is the main concern, as temperature

gets higher during printing, hence printing is usually done in a

controlled environment.

c) Binders: They can be combinations of one or more polymers and

act as binding media between ink and substrate. The ideal

requirement of a binder is to provide good adhesion with

comparatively low viscosity, considering end use performance at

the customer end. Similar resins as used in flexography and

rotogravure are generally used for ink jet formulations that provide

durable coating, but they must have a lower degree of

polymerization (molecular weight) to generate appropriate inks

with lower viscosity (13).

d) Additives: Like other printing inks, inkjet inks also have additives

that impart specific properties, such as modifying surface tension,

plasticizing binders, reducing tack, improving flow properties, etc.

In inkjet inks, even 0.1% of addition of an additive could

drastically affect ink performance. The main additive used in inkjet

is conductive salt that provides conductivity to droplets in

continuous ink jet ink formulations. Again, conductive salts are

15

only added into continuous ink jet ink formulations. Metal salt

impurities can also be used to induce conductivity, but might lead

to issues such as corrosion.

Essential Color Management Concepts

Metamerism

It is an effect where two colors or shades match visually in one lighting

condition, but do not match when compared in other light source. Such two

samples are called a metameric pair, hence the phenomenon is called the

metamerism effect (17). Metameric nature is common and is an important issue in

various application fields such as automotive, textile and graphic arts.

Cause of Metamerism

There are three different types of cones present in human eyes. Integrated

stimulation of these three types of cones causes the human eye to responds to

light, which is a compilation of various wavelengths. The human eye does not

respond to light on wavelength to wavelength basis. If two stimuli are identical, or

somewhat the same, to the stimulus created by three cones in human retina, then

those two stimuli visually appear to be the same, even though their spectral

distributions are different from each other (17). For a visually matching pair, if

the spectral distribution of one color crosses the spectral distribution of another

color three or more times, then usually that pair is considered as a metameric pair

(18). But, if two spectral curves cross one another any number of times and the

16

RMS difference (with unit weight) is less than 1%, then the metamerism effect is

unnoticeable to human eyes and corresponds to small ∆E under any illuminant.

Metamerism can be divided into two types:

1) Illuminant Metamerism: In this type two pairs match one another under a

certain illuminant, but do not under another light source for the same

observer. To avoid this phenomenon, pairs should be matched under a D

illuminant light source and be tolerable under a number of non D

illuminants.

2) Observer Metamerism: This kind of metamerism occurs when two pairs

match for certain observers but at the same time are mismatches for other

observers. It might occur if pairs are being observed at different CIE

observer conditions, such as one at 2° viewing angle and another at 10°

viewing angle. Also various color sensitivities of different observers is

another probable cause for observer metamerism.

Metamerism Index

The greater is the difference between spectral power reflectance of two

metameric samples, then a greater amount change in color occurs when

illuminants or observers are changed. Though it is impossible to eliminate

metamerism, it can be reduced to certain acceptable levels. The degree of

metamerism can be quantified by calculating the metamerism index. Metamerism

indices can be of two types; general indices and special indices.

17

1) General indices: These are spectral indices based on spectral differences

between the members of the metameric pair and are independent of

illuminant. Bridgeman`s Index (BMAN) was used for calculation of an

index, but it does not consider the variation of eye sensitivity throughout

the visible spectrum of light. Hence the Nimeroff and Yurow`s index was

introduced (19). Even though the new index is modified, if the spectral

difference is averaged throughout the spectrum, it decreases the difference

in spectral values and may be lessened as two ends of spectra are

approached. Therefore, it is important to calculate the difference and it is

mainly dependent on illuminant and observer. Hence, it is more

mathematically accurate to use a special metamerism index than a general

one (17).

2) Special indices: These indices are based on XYZ tristimulus values.

Especially for illuminants, there are two commonly used special

metamerism indices:

a) CIE special metamerism index, in which metamerism index is

calculated assuming the ΔE difference between the pair under

the reference illuminant is equal to zero.

b) DIN 6172 metamerism index, in which metamerism index is

calculated assuming the ΔE difference between the pair under

reference illuminant is not equal to zero (18).

18

Special metamerism indices should not be used if ΔE difference between

two samples under reference illuminant is more than 5 (20). CIE special

metamerism index can be calculated based on following formula:

𝑀𝐼 = √(𝛥𝐿𝑛1 − 𝛥𝐿𝑛2)2 + (𝛥𝑎𝑛1 − 𝛥𝑎𝑛2)2 + (𝛥𝑏𝑛1 − 𝛥𝑏𝑛2)2 (1)

Where, n1 is the 1st illuminant and n2 is the 2nd illuminant and Δ=Value of sample

– Values of standard (21).

Equation 1 is algebraically equal to both the CIE and DIN indices, but the

interpretation is different. Under the CIE index, the colors perfectly match under

an illuminant and small MI means they match well under a second illuminant. For

the DIN index, the colors are assumed to match well under an illuminant and

small MI means they match almost as well under a second illuminant. In either

case, if the MI value is high, then there is a significant color difference between

the sample pair under different illuminants.

UCR and GCR

UCR (Under Color Removal) and GCR (Gray Component Replacement)

basically deal with color separations of four process colors and are widely used in

offset litho printing due to its advantages, but it has equally important applications

in other printing processes. As per the subtractive color theory, when all

secondary colors (Cyan, Magenta and Yellow) are printed over the others, they

should create black, but in reality they give brownish or muddy black appearance.

Black ink is used to compensate for this deficiency, hence black is called the Key

color in color printing, thus the K in CMYK. The main difference between UCR

19

and GCR is that UCR is process of removal of cyan, magenta and yellow,

wherever black is present, whereas GCR is process of replacing the gray

component in an image (made from CMY) and replacing with black ink (22).

GCR is preferred over UCR because UCR deals with removal of CMY

inks in dark and near neutral areas. Contrary to that, GCR is capable of replacing

gray component from all colors in separation including highlights. Use of GCR

has multiple advantages, such as fewer trapping problems, less dot gain

fluctuation and fewer registration problems of use of only one ink instead of three.

Use of GCR reduces consumption of ink substantially, reducing cost of an ink by

50% (23). Also GCR improves color gamut, as level black increases, color gamut

volume also increase to some extent (24). The color gamut volume, is a volume in

Lab space that represents the number of colors that the device (here ink jet

printer) can produce with a tolerance of the √3 (25).

20

CHAPTER II

PROBLEM STATEMENT

Currently, most of the décor or wood-grain printing is mainly done by the

gravure printing process, due to its effectiveness in achieving consistent results in

long run jobs. But as market requirements are changing, customers are looking for

more diverse wood-grain design jobs, specifically in small quantities. Gravure

printing is cost effective only if it is used for large quantity jobs because of

relatively high cost for cylinder engraving. Hence, many printers are exploring

other printing processes for wood-grain prototyping and production of small

quantity jobs. Every conventional impact printing process requires an image

carrier that increases cost. Therefore, the inkjet printing process is one the most

feasible options to print wood-grain patterns in a most cost effective way with

flexibility of short quantity jobs. But inkjet printing has its own disadvantages,

too. An inkjet printer uses process inks, whereas gravure uses spot color inks to

print wood-grain patterns. Thus, color matching is one of the main concerns while

doing ink jet prototyping. Simultaneously, pigments used in inkjet inks are

different from those used in gravure inks. Hence, it often leads to metamerism.

Color matching issues can be resolved by implementation of color

management systems into the process workflow. Using customized ICC profiles,

instead of default ICC profiles from the RIP, gives a comparatively closer color

match in prototyping. Metamerism can be minimized by using the same or

21

somewhat similar types of pigments for both printing processes. It helps to get a

closer spectral match between samples, but it is an expensive option.

The focus of this study was to achieve close color match between two

printing processes by conducting a Design of Experiments of multiple level

factors. Experiments were carried out mainly in two phases.

22

CHAPTER III

EXPERIMENTAL

Phase-I

Four gravure printed shades of wood grains were selected as reference

patches. These four shades were printed as solid patches for ease of measurement.

CIE LAB values of gravure reference patches were measured using an X-Rite

Ci6x spectrophotometer. Four sample patches were constructed in Adobe

Illustrator by assigning previously measured CIE-LAB values of the reference

patches. Patches were labeled as Galaxy Oak, Smooth Grey, Hunter 655 and

Rustic Maple, respectively. The primary focus of Phase-I was to print sample

patches using Roland VS 540i inkjet printer and closely color match it with

reference patches. (∆E less than 5) and also to analyze significance of custom

created ICC profile in close color matching in comparison with the default printer

profile as well as to determine the significance of manual GCR adjustment.

A customized ICC profile was created using X-Rite ‘i1Profiler’ profile

making software. For customized ICC profile creation, no standard color chart

was used instead it was created using the 800 patch chart from i1Profiler software.

Sample Patches (Figure 5) were printed on the Roland VS 540i inkjet printer by

applying the standard printer profile and customized ICC profile. Patches were

again printed by applying customized ICC profile, but with additional manual

GCR adjustment. In manual GCR adjustment, a % of CMY ink was replaced by

the same % of K ink. ∆E and metamerism indices for the four patches were

23

calculated and spectral graphs were compared to determine the initial significance

of custom created ICC profile over default printer profile as well as effectiveness

of manual GCR adjustment and its effect on metamerism index.

Figure 5: Sample Patches, with CIE LAB values.

Phase-II

To analyze the influence of various factors on metamerism, a Design of

Experiments (DOE) was conducted by using different factors. Factors in DOE

included GCR level settings, release coat weight and use of tie coat. (Tie coat is

24

an acrylic based clear used to promote adhesion between printed ink and

adhesive.) Table 1 shows number of trials and factors for a DOE experiment.

Table 1: Trials for Design of Experiments

Trials Factor 1: Release

Coat Weight

(g/m2)

Factor 2: Use of

Tie Coat

Factor 3: GCR

levels

1 7 Yes Minimum

2 10.5 No Medium+

3 7 Yes Maximum

4 10.5 No Minimum

5 7 Yes Medium+

6 10.5 No Maximum

7 7 No Minimum

8 10.5 Yes Medium+

9 7 No Maximum

10 10.5 Yes Minimum

11 7 No Medium+

12 10.5 Yes Maximum

Trials 3, 6, 9 and 12 were conducted again with additional manual GCR

adjustment in Adobe illustrator to check its effect on metamerism index. Spectral

25

graphs were compared. Metamerism indices and ∆E were calculated to

understand effect of DOE factors on metamerism index.

Selection Criteria of Factors for Design of Experiments

Printed wood grain products are transferred onto the base wood by means

of heat and pressure. Thus, all layers of the product need to print in reverse order.

All the layers of the wood grains in order are shown in the Figure 6.

Figure 6: Schematic of Wood Grain Layers.

Factor 1: Release coat weight

After application of wood grain to the wood, release coat is the top layer

of the wood grain that gives chemical and abrasive resistance to wood grain

product. In the absence of tie coat, the release coat is the 1st layer that comes in

contact with inkjet ink. Release coat weight decides the degree of chemical and

abrasive resistance as well as gloss or matt finish of the product. Initially

substrates with 3 g/m2 of release coat were used to create the customized ICC

26

profile. Substrates were unable to take more than 100% total ink limit value

during media calibration for the Roland VS540i inkjet printer. Cracks were

observed after drying. The recommended minimum total ink limit as per printer

manufacturer is 140% to achieve acceptable print quality. To increase total ink

limit value, substrates with higher release coat were used. 7g/m2 and 10.5g/m2

substrates showed higher total ink limit than 140%. Higher release coat substrates

showed some cracking but it was not as visible to naked eyes. 7g/m2 and 10g/m2

were able to accept 180% and 200% of total ink limit, respectively.

Factor 2: Use of Tie Coat

The vehicles in the inkjet ink were making polymers in release coat less

elastic and the increased stresses due to shrinking were causing cracks in a print

area after drying.

In wood grain printing, tie coat is usually used to promote adhesion

between printed ink and adhesive but it can also be used as an alternative to the

original release coat. Tie coat has low molecular weight, hence it creates

relatively soft and flexible layer of coating than release coat, which avoids

cracking after drying. But use of tie leads to reduced rub resistance because of its

low molecular weight hence, tie coat was coated over release coat to maintain

original rub resistance of the substrate as well as to avoid cracking.

When substrates with tie coat over release coat were calibrated for Roland

VS540i inkjet printer, they showed no ink cracking. However, tie coat did not

27

significantly improve total ink limit capability of substrate. 7g/m2 and 10g/m2

substrates with tie coat both were able to accept 160% of total ink limit.

Factor 3: GCR settings

Unlike older version of X-Rite profile making software “Profile Maker

5.0”, the new software i1Profiler does not specify percent of grey component

replacement. Instead it provides 8 different steps under the name “Black

Generation Curve”. 8 GCR settings options are minimum, light, light+, medium,

medium+, heavy, heavy+ and maximum. To analyze effect of the GCR, three

settings of GCR (minimum, medium+ and maximum) were used in the design of

experiments.

The fundamental approach behind the use of factors 1 and 2 was to

increase color gamut volume by improving total ink limit and to analyze the effect

of increased color gamut volume on metamerism index. Use of factor 3 was

straightforward i.e. to understand effect of increasing GCR setting on metamerism

index.

28

CHAPTER IV

RESULTS AND DISCUSSION

Phase-I

For all four patches, ∆E comparison of inkjet sample patches and gravure

reference patches showed less than five color difference. Thus, the close color

matches shown in Figures 7-10.

Effect of Customized ICC Profile and Manual GCR Adjustment on ∆E

For all four patches, ∆E comparison of inkjet sample patches and gravure

reference patches (Figures 7-10) show that customized the ICC profile

significantly decreased color difference for all illuminants. On the other hand,

manual GCR adjustment in addition to customized ICC profile increased color

difference for all patches, except Galaxy Oak.

Figure 7: Galaxy Oak: Phase-I ∆E Comparison.

0.00

2.00

4.00

6.00

8.00

10.00

12.00

D65 CWF A10

DEL

TA E

ILLUMINANTS

Galaxy Oak: Phase-I Delta E

Default Printer Profile

Customized ICC profile

Customized ICC profile withManual adjustment

29

Figure 8: Smooth Grey: Phase-I ∆E Comparison.

Figure 9: Hunter 655 Phase-I ∆E Comparison.

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

D65 CWF A10

DEL

TA E

ILLUMINANTS

Smooth Grey: Phase-I Delta E

Default Printer Profile

Customized ICC profile

Customized ICC profile withManual adjustment

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

D65 CWF A10

DEL

TA E

ILLUMINANTS

Hunter655: Phase-I Delta E

Default Printer Profile

Customized ICC profile

Customized ICC profile withManual adjustment

30

Figure 10: Rustic Maple Phase-I ∆E Comparison.

Effect of Customized ICC Profile and Manual GCR Adjustment on Metamerism

Index

Metamerism Index comparison of all four sample patches (Figures 11-14)

showed that customized ICC profile significantly improved the metamerism index

for all illuminants and unlike ∆E difference, metamerism index was decreased

further by use of manual GCR adjustment in the custom ICC profile, except for

Galaxy Oak.

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

D65 CWF A10

DEL

TA E

ILLUMINANTS

Rustic Maple: Phase-I Delta E

Default Printer Profile

Customized ICC profile

Customized ICC profile withManual adjustment

31

Figure 11: Galaxy Oak Phase-I Metamerism Index.

Figure 12: Smooth Grey Phase-I Metamerism Index.

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

D65 & CWF CWF & A10 A10 & D65

MET

AM

ERIS

M IN

DEX

ILLUMINANTS

Galaxy Oak: Phase-I Metamerism Index

Default Printer Profile

Customized ICC profile

Customized ICC profile withManual adjustment

0.00

1.00

2.00

3.00

4.00

5.00

6.00

D65 & CWF CWF & A10 A10 & D65

MET

AM

ERIS

M IN

DEX

ILLUMINANTS

Smooth Grey: Phase-I Metamerism Index

Default Printer Profile

Customized ICC profile

Customized ICC profile withManual adjustment

32

Figure 13: Hunter 655 Phase-I Metamerism Index.

Figure 14: Rustic Maple: Phase-I Metamerism Index.

Effect of Customized ICC Profile and Manual GCR Adjustment on Spectral

Curves

Spectral reflectance of gravure printed reference patches and inkjet printed

sample patches with default printer profile, manual GCR adjustment and

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

D65 & CWF CWF & A10 A10 & D65

MET

AM

ERIS

M IN

DEX

ILLUMINANTS

Hunter655: Phase-I Metamerism Index

Default Printer Profile

Customized ICC profile

Customized ICC profile withManual adjustment

0.00

1.00

2.00

3.00

4.00

5.00

6.00

D65 & CWF CWF & A10 A10 & D65

MET

AM

ERIS

M IN

DEX

ILLUMINANTS

Rustic Maple: Phase-I Metamerism Index

Default Printer Profile

Customized ICC profile

Customized ICC profile withManual adjustment

33

customized ICC profile were plotted on graphs for comparison. Spectral

reflectance plots of all patches (Figures 15-18) showed that custom created ICC

profiles brought spectral reflectance curve closer to the reference spectral curve,

mainly because of improvement in ∆E (especially improvement in lightness).

Manual GCR setting, in addition to custom ICC profiles improved spectral plot to

some extent, but not in a significant amount except for Smooth Grey Patch.

Figure 15: Galaxy Oak Phase-I Spectral Curve Comparison.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Galaxy Oak: Spectral Curve Distribution

Reference Patch

Sample Patch withDefault printer profile

Sample Patch withManual Adjust

Sample Patch withCustomized profile

34

Figure 16: Smooth Grey Phase-I Spectral Curve Comparison.

Figure 17: Hunter 655 Phase-I Spectral Curve Comparison.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Smooth Grey: Spectral Curve Distribution

Reference Patch

Sample Patch withDefault printer profile

Sample Patch withManual Adjust

Sample Patch withCustomized profile

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Hunter655: Spectral Curve Distribution

Reference Patch

Sample Patch with Defaultprinter profile

Sample Patch with ManualAdjust

Sample Patch withCustomized profile

35

Figure 18: Rustic Maple Phase-I Spectral Curve Comparison.

Phase-II

Use of a custom created ICC profile showed significant improvement in

∆E in comparison with default RIP printer profile. Manual adjustment of GCR

showed some improvement in spectral curve and metamerism index. To explore

the effect of different factors on the metamerism index, a design of experiments

was conducted. Manual GCR adjustment were done to the trials with maximum

GCR setting and compared with other DOE trials.

For ease of analysis 12 trials were divided into 4 substrate types based on

release coat weight and use of tie coat and each substrate was analyzed for 3

different GCR settings. Four different color patches were printed to understand

for which CIE L*a*b* values improvement in metamerism index was significant.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Rustic Maple: Spectral Curve Distribution

Reference Patch

Sample Patch with Defaultprinter profile

Sample Patch with ManualAdjust

Sample Patch withCustomized profile

36

Effect of GCR Settings on ∆E and Metamerism Index

To analyze the effect of GCR settings on ∆E and Metamerism Index

simultaneously, GCR settings are plotted on the X-axis, whereas both ∆E and

Metamerism index are plotted on the Y-axis for all Figures from 19 to 34. For all

types of substrates, color patches and for all illuminants (D65, CWF and A10), the

minimum GCR setting showed the highest metameric index, whereas the

maximum GCR setting showed the smallest metameric index (Figures 19 to 34).

∆E and GCR settings did not show any significant correlation between each other

except for the Smooth Gray patch. For Smooth Grey patch, ∆E decreased

significantly with increase in GCR settings (Figures 20-32), contrary to that for

rest of the patches ∆E fluctuated by 1-2 ∆E range. Among all patches Smooth

Grey patch showed the highest improvement in metamerism index (Figures 20,

24, 28 and 32), Hunter 655 showed least improvement whereas Galaxy Oak and

Rustic Maple showed slightly more improvement than Hunter 655. For all trials

manual GCR adjustment neither improved metamerism index nor ∆E to a

significant extent.

I) 7g/m2 release coat with tie coat

37

Figure 19: Galaxy Oak 7g/m2 Release Coat + Tie Coat- ∆E & Metamerism Index.

Figure 20: Smooth Grey 7g/m2 Release Coat + Tie Coat- ∆E & Metamerism

Index.

0

0.5

1

1.5

2

2.5

3

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

7g/m2 Release Coat plus Tie Coat: Galaxy Oak

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0

0.5

1

1.5

2

2.5

3

3.5

4

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

7g/m2 Release Coat plus Tie Coat: Smooth Grey

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

38

Figure 21: Hunter 655 7g/m2 Release Coat + Tie Coat- ∆E & Metamerism Index.

Figure 22: Rustic Maple 7g/m2 Release Coat + Tie Coat- ∆E & Metamerism

Index.

0

1

2

3

4

5

6

0

1

2

3

4

5

6

7

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

7g/m2 Release Coat plus Tie Coat: Hunter 655

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

0

0.5

1

1.5

2

2.5

3

3.5

4

0

1

2

3

4

5

6

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

7g/m2 Release Coat plus Tie Coat: Rustic Maple

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

39

II) 7g/m2 release coat

Figure 23: Galaxy Oak 7g/m2 Release Coat only- ∆E & Metamerism Index.

Figure 24: Smooth Grey 7g/m2 Release Coat only- ∆E & Metamerism Index.

0

0.5

1

1.5

2

2.5

0

0.5

1

1.5

2

2.5

3

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

7g/m2 Release Coat: Galaxy Oak

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

7g/m2 Release Coat: Smooth Grey

D65: DeltaE

CWF: DeltaE

A10: DeltaE

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

40

Figure 25: Hunter 655 7g/m2 Release Coat only- ∆E & Metamerism Index.

Figure 26: Rustic Maple 7g/m2 Release Coat only- ∆E & Metamerism Index.

0

1

2

3

4

5

6

0

1

2

3

4

5

6

7

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

7g/m2 Release Coat: Hunter 655

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

7g/m2 Release Coat: Rustic Maple

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

41

III) 10.5g/m2 release coat with tie coat

Figure 27: Galaxy Oak 10.5 g/m2 Release Coat + Tie Coat- ∆E & Metamerism

Index.

Figure 28: Smooth Grey 10.5 g/m2 Release Coat + Tie Coat- ∆E & Metamerism

Index.

0

0.5

1

1.5

2

2.5

0

0.5

1

1.5

2

2.5

3

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

10.5g/m2 Release Coat plus Tie Coat: Galaxy Oak

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0

0.5

1

1.5

2

2.5

3

3.5

4

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

10.5g/m2 Release Coat plus Tie Coat: Smooth Grey

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

42

Figure 29: Hunter 655 10.5 g/m2 Release Coat + Tie Coat- ∆E & Metamerism

Index.

Figure 30: Rustic Maple 10.5 g/m2 Release Coat + Tie Coat- ∆E & Metamerism

Index.

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0

1

2

3

4

5

6

7

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

10.5g/m2 Release Coat plus Tie Coat: Hunter 655

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0

1

2

3

4

5

6

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

10.5g/m2 Release Coat plus Tie Coat: Rustic Maple

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

43

IV) 10.5 g/m2 release coat

Figure 31: Galaxy Oak 10.5 g/m2 Release Coat only- ∆E & Metamerism Index.

Figure 32: Smooth Grey 10.5 g/m2 Release Coat only- ∆E & Metamerism Index.

0

0.5

1

1.5

2

2.5

3

0

0.5

1

1.5

2

2.5

3

3.5

4

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

10.5 g/m2 Release Coat: Galaxy Oak

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

10.5 g/m2 Release Coat: Smooth Grey

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

44

Figure 33: Hunter 655 10.5 g/m2 Release Coat only- ∆E & Metamerism Index.

Figure 34: Rustic Maple 10.5 g/m2 Release Coat only- ∆E & Metamerism Index.

0

1

2

3

4

5

6

0

1

2

3

4

5

6

7

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M I

ND

EX

DEL

TA E

GCR SETTINGS

10.5 g/m2 Release Coat: Hunter 655

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

Minimum Medium+ Maximum Manual

MET

AM

ERIS

M IN

DEX

DEL

TA E

GCR SETTINGS

10.5 g/m2 Release Coat: Rustic Maple

D65: Delta E

CWF: Delta E

A10: Delta E

Met. IndexD65 & CWF

Met. IndexCWF & A10

Met. IndexA10 & D65

45

Effect of GCR Settings on Spectral Curve Distribution

As manual adjustment did not show any significant improvement in

metamerism index, hence it was not included in Spectral Distribution

Curve comparison. Spectral reflectance of gravure printed reference

patches, inkjet printed sample patches with Minimum, Medium+, and

Maximum GCR setting were plotted on a graph for comparison.

Spectral graphs, of all color patches, crossed reference patches spectral

reflectance curve patch thrice and thus considered metameric. Even

though color patches were metameric, Spectral reflectance curves of

maximum GCR setting were closest to the spectral curve of reference

patch followed by medium GCR setting and minimum GCR setting

spectral curve respectively. Among all patches, Smooth Grey patch

showed highest improvement in spectral curve (Figure 36, 40, 44 and 48),

Hunter 655 showed the least improvement (Figure 37, 41, 45 and 49),

whereas Galaxy Oak (Figure 35, 39, 43 and 47) and Rustic Maple (Figure

38, 42, 46 and 50) showed slightly more improvement than Hunter 655.

I) 7g/m2 release coat with tie coat

46

Figure 35: Spectral Curve 7g/m2 plus Tie Coat- Galaxy Oak.

Figure 36: Spectral Curve 7g/m2 plus Tie Coat- Smooth Grey.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

40

0

42

0

44

0

46

0

48

0

50

0

52

0

54

0

56

0

58

0

60

0

62

0

64

0

66

0

68

0

70

0

72

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 7g/m2 plus tie Galaxy Oak

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

38

0

40

0

42

0

44

0

46

0

48

0

50

0

52

0

54

0

56

0

58

0

60

0

62

0

64

0

66

0

68

0

70

0

72

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 7g/m2 plus tie Smooth Grey

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

47

Figure 37: Spectral Curve 7g/m2 plus Tie Coat- Hunter 655.

Figure 38: Spectral Curve 7g/m2 plus Tie Coat- Rustic Maple.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

40

0

42

0

44

0

46

0

48

0

50

0

52

0

54

0

56

0

58

0

60

0

62

0

64

0

66

0

68

0

70

0

72

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 7g/m2 plus tie Hunter 655

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

40

0

42

0

44

0

46

0

48

0

50

0

52

0

54

0

56

0

58

0

60

0

62

0

64

0

66

0

68

0

70

0

72

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 7g/m2 plus tie Rustic Maple

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

48

II) 7g/m2 release coat

Figure 39: Spectral Curve 7g/m2 Release Coat only- Galaxy Oak.

Figure 40: Spectral Curve 7g/m2 Release Coat only- Smooth Grey.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 7g/m2 : Galaxy

Oak

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 7g/m2: Smooth Grey

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

49

Figure 41: Spectral Curve 7g/m2 Release Coat only-Hunter 655.

Figure 42: Spectral Curve 7g/m2 Release Coat only- Rustic Maple.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 7g/m2: Hunter 655

Reference Patch

Sample Patch with Min.GCR

Sample Patch with Med+.GCR

Sample Patch with Max.GCR

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 7g/m2: Rustic Maple

Reference Patch

Sample Patch with Min.GCR

Sample Patch with Med+.GCR

Sample Patch with Max.GCR

50

III) 10.5g/m2 release coat with tie coat

Figure 43: Spectral Curve 10.5 g/m2 plus Tie Coat- Galaxy Oak.

Figure 44: Spectral Curve 10.5 g/m2 plus Tie Coat- Smooth Grey.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTI

ON

WAVELENGTH (NM)

Spectral Curve: 10.5g/m2 plus tie Galaxy Oak

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTI

ON

WAVELENGTH (NM)

Spectral Curve: 10.5g/m2 plus tie Smooth Grey

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

51

Figure 45: Spectral Curve 10.5 g/m2 plus Tie Coat- Hunter 655.

Figure 46: Spectral Curve 10.5 g/m2 plus Tie Coat- Rustic Maple.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTI

ON

WAVELENGTH (NM)

Spectral Curve: 10.5g/m2 plus tie Hunter 655

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTI

ON

WAVELENGTH (NM)

Spectral Curve: 10.5g/m2 plus tie Rustic Maple

Reference Patch

Sample Patch with Min.GCR

Sample Patch withMed+. GCR

Sample Patch with Max.GCR

52

IV) 10.5 g/m2 release coat

Figure 47: Spectral Curve 10.5 g/m2 Release Coat only- Galaxy Oak.

Figure 48: Spectral Curve 10.5 g/m2 Release Coat only - Smooth Grey.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 10.5 g/m2: Galaxy Oak

Reference Patch

Sample Patch with Min.GCR

Sample Patch with Med+.GCR

Sample Patch with Max.GCR

0.00

0.10

0.20

0.30

0.40

0.50

0.60

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 10.5 g/m2: Smooth Grey

Reference Patch

Sample Patch with Min.GCR

Sample Patch with Med+.GCR

Sample Patch with Max.GCR

53

Figure 49: Spectral Curve 10.5 g/m2 Release Coat only - Hunter 655.

Figure 50: Spectral Curve 10.5 g/m2 Release Coat only- Rustic Maple.

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 10.5 g/m2: Hunter 655

Reference Patch

Sample Patch with Min.GCR

Sample Patch with Med+.GCR

Sample Patch with Max.GCR

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

38

0

41

0

44

0

47

0

50

0

53

0

56

0

59

0

62

0

65

0

68

0

71

0

SPEC

TRA

L R

EFLE

CTA

NC

E

WAVELENGTH (NM)

Spectral Curve: 10.5 g/m2: Rustic Maple

Reference Patch

Sample Patch with Min.GCR

Sample Patch with Med+.GCR

Sample Patch with Max.GCR

54

Effect of Color Gamut Volume on Metamerism Index

Figure 51 shows color gamut volume comparison of all 4 substrates.

ICC profiles for the 7g release coat plus tie coat and 10.5g release coat plus tie

coat substrate were created with 160% total ink limit values, whereas 7g

release coat and 10.5g release coat substrates without any tie coat were

profiled with 180% and 200% total ink limit, respectively. As expected,

higher total ink limit substrate i.e. 10.5 g with no tie coat showed the highest

color gamut volume and lowest total ink limit substrate i.e. 7g plus tie coat

showed the smallest color gamut volume. Apparently, the tie coat stopped

cracking of the ink but restricted the color gamut volume of the substrates

drastically because of low total ink limit value around 140%.

Figure 51: Gamut Volume Comparison

7g only (304,802 CCU)

10.5g only (357,646 CCU)

10.5g plus tie coat (147,850 CCU)

7g plus tie coat (138,827 CCU)

55

Figure 52: Metamerism Index vs. Color Gamut Volume- Galaxy Oak

Figure 53: Metamerism Index vs. Color Gamut Volume- Smooth Grey

0

0.5

1

1.5

2

2.5

138827 CCU(7g plus tie

coat)

147850 CCU(10.5g plus

tie coat)

304802 CCU(7g only)

357646 CCU(10.5g only)

MET

AM

ERIS

M IN

DEX

SUBSTATES WITH INCREASING COLOR GAMUT VOLUME

Metamerism Index vs. Color Gamut Volume: Galaxy Oak

D65 & CWF Met. Index

CWF & A10 Met. Index

A10 & D65 Met. Index

0

0.5

1

1.5

2

2.5

3

138827 CCU(7g plus tie

coat)

147850 CCU(10.5g plus

tie coat)

304802 CCU(7g only)

357646 CCU(10.5g only)

MET

AM

ERIS

M IN

DEX

SUBSTATES WITH INCREASING COLOR GAMUT VOLUME

Metamerism Index vs. Color Gamut Volume: Smooth Grey

D65 & CWF Met. Index

CWF & A10 Met. Index

A10 & D65 Met. Index

56

Figure 54: Metamerism Index vs. Color Gamut Volume- Hunter655

Figure 55: Metamerism Index vs. Color Gamut Volume- Rustic Maple

To analyze the effect of color gamut volume over metamerism index, the

metamerism index of substrates were plotted against color gamut volume for all

four patches (Figures 52-55).

0

1

2

3

4

5

6

138827 CCU(7g plus tie

coat)

147850 CCU(10.5g plus

tie coat)

304802 CCU(7g only)

357646 CCU(10.5g only)

MET

AM

ERIS

M IN

DEX

SUBSTATES WITH INCREASING COLOR GAMUT VOLUME

Metamerism Index vs. Color Gamut Volume: Hunter 655

D65 & CWF Met. Index

CWF & A10 Met. Index

A10 & D65 Met. Index

0

0.5

1

1.5

2

2.5

3

3.5

4

138827 CCU(7g plus tie

coat)

147850 CCU(10.5g plus

tie coat)

304802 CCU(7g only)

357646 CCU(10.5g only)

MET

AM

ERIS

M IN

DEX

SUBSTATES WITH INCREASING COLOR GAMUT VOLUME

Metamerism Index vs. Color Gamut Volume: Rustic Maple

D65 & CWF Met. Index

CWF & A10 Met. Index

A10 & D65 Met. Index

57

For all color patches except Smooth Grey, the metamerism index between

illuminant D65 & CWF and metamerism index between illuminant CWF & A10,

increased with increase in color gamut volume. Metamerism index between

illuminant A10 and D65 did not changed significantly with increase in color

gamut volume.

For Smooth Grey patch, metamerism index did not show any correlation

with increasing color gamut volume. But overall metamerism index definitely

increased for higher gamut volume substrates but not in linear way. However, in

many cases the larger color gamut profile gave lower ∆E values, so higher MI

values could indicate good color matches for different illuminants.

Design of Experiments Analysis

All patches were analyzed for Analysis of Variance. Tables 2 to 5 show

the Analysis of Variance (ANOVA) results for metamerism index obtained from

12 DOE trials for all patches. P-values from the Tables 2-5 showed that for all

patches except Hunter 655, GCR settings significantly influenced Metamerism

Index followed by tie coat. For Hunter 655 patch, use of tie coat was the most

significant factor. However, release coat weight had an insignificant effect on the

Metamerism Index response. This indicates that after a certain release coat

weight, there is no value to increasing the release coat weight. Based on the

observed results, this value is about 7 g/m2.

58

Table 2: Analysis of Variance (ANOVA) for Smooth Grey.

Table 3: Analysis of Variance (ANOVA) for Hunter 655.

59

Table 4: Analysis of Variance (ANOVA) for Galaxy Oak.

Table 5: Analysis of Variance (ANOVA) for Rustic Maple.

The main effect graph was ploted to determine the best possible

combination of GCR settings and Tie coat for minimum metamerism. Figures 56-

59 show main effect plot diagram for all patches.

60

Figure 56: Main Effect Plot- Smooth Grey.

Figure 57: Main Effect Plot- Hunter 655.

61

Figure 58: Main Effect Plot- Galaxy Oak.

Figure 59: Main Effect Plot- Rustic Maple.

The main effect plot (Figures 56-59) suggested that use of tie coat with

maximum GCR setting would give reduced metmaerism index for all patches.

62

CHAPTER V

CONCLUSION

This study outlined the workflow that can reduce metamerism to some

extent for wood grain printing.

The results of Phase-I showed that custom created ICC profile improved

metamerism index and ∆E difference significantly, when compared with the

generic RIP printer profile. Analysis of spectral reflectance curves also justified

the significance of custom created ICC profile over generic RIP printer profile.

Manual GCR adjustment in addition to custom created ICC profile decreased

metamerism index further but at the same time increased ∆E difference to some

extent.

Design of Experiments consisting of 12 trials was conducted in Phase-II

using different multi-level factors. Results of Phase-II showed that increased GCR

settings had considerable amount of impact on metamerism index. Impact of GCR

settings varied as per color shade. Darker patches showed the highest reduction in

metamerism index, contrary to that, the response to GCR settings by lighter

patches was none or insignificant. Analysis of spectral reflectance showed similar

results for dark and light patches of colors. GCR settings neither improved nor

deteriorated color difference. ∆E difference fluctuated up and down in range of 1-

2 ∆E units. Increased color gamut volume and metamerism index had no linear

correlation between each other, but overall increase in color gamut volume

increased metamerism index for all color types of color patches.

63

ANOVA analysis showed that GCR setting was the most influential factor

followed by use of the tie coat. Release Coat weight was an insignificant factor. In

addition to that, the main effect plot showed maximum GCR settings with the use

of tie coat would be the best combination of those tested get maximum reduction

in metamerism index.

Recommendation for Future Work

Metamerism has huge impact on almost every industry that involves color

pigments. This study evaluated the effect of different GCR settings on

metamerism index for conventional process colors i.e. CMYK inks. For future

study, it is recommended to explore effect of GCR where 7 colors inks (extended

color gamut) are used for printing. Also, substrates used for profiling in this study

were able to sustain up to 200% of total ink limit, which is exactly half of the

possible ink limit achievable by any process color printer. It is recommended that

future study should be done using substrate/ink combinations that can accept at

least 260% total ink limit value.

64

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23) Zou, Jiayi. “An Investigation of Ink Usage in Offset Process Printing.”

(2012). ScholarWorks. Rochester Institute of Technology. Web.

<http://scholarworks.rit.edu/theses/3885/>

67

24) Spiridonov, I., and M. Shopova. “Determination of the Effect of Gray

Component Replacement Level on Colorimetric Characteristics of Color

Proof.” Journal of Chemical Technology and Metallurgy 48.3 (2013):

247-53. Print.

25) V. Chovancova-Lovell and P. D. Fleming III, “Color Gamut – New Tool

in the Pressroom?”, TAPPI J, February 2009, pp4-11

68

APPENDICES

Table 6: 7g/m2 only Metamerism Index and ∆E for Galaxy Oak

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 83.41 0.79 5.08

Reference

A-10 83.85 1.87 5.42

CWF 83.76 0.6 5.92

2 D65 82.77 -1.82 5.78 2.78 2.24

Minimum

GCR

A-10 82.95 1.16 4.97 1.23 0.89

CWF 82.57 -0.44 6.24 1.61 1.71

3 D65 83.02 -1.84 5.5 2.69 2.10

Medium

GCR

A-10 83.18 0.99 4.71 1.31 0.78

CWF 82.83 -0.51 5.91 1.45 1.67

4 D65 82.85 -1.76 5.46 2.64 1.88

Maximum

GCR

A-10 83.01 0.85 4.74 1.49 0.72

CWF 82.72 -0.57 5.91 1.57 1.51

5 D65 82.89 -1.74 5.46 2.61 1.88

Manual A-10 83.06 0.88 4.75 1.43 0.72

69

GCR CWF 82.76 -0.55 5.92 1.52 1.51

Table 7: 7g/m2 only Metamerism Index and ∆E for Smooth Grey

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 67.02 0.3 3.05

Reference

A-10 67.27 0.83 3.27

CWF 67.25 0.12 3.56

2 D65 68.72 -2.97 4.29 3.89 4.72

Minimum

GCR

A-10 68.66 1.83 2.52 1.87 2.12

CWF 67.83 -0.29 4.17 0.94 3.14

3 D65 68.82 -2.15 3.86 3.15 4.09

Medium

GCR

A-10 68.82 2.11 2.42 2.18 1.81

CWF 68.05 0.1 3.73 0.82 2.70

4 D65 68.96 -1.25 3.29 2.49 2.66

Maximum

GCR

A-10 69.03 1.69 2.39 2.15 1.17

CWF 68.52 0.15 3.35 1.29 1.77

5 D65 68.7 -1.27 3.28 2.31 2.67

70

Manual

GCR

A-10 68.77 1.68 2.38 1.94 1.17

CWF 68.26 0.14 3.34 1.03 1.78

Table 8: 7g/m2 only Metamerism Index and ∆E for Hunter 655

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 73.88 8.2 20.06

Reference

A-10 76.05 10.79 23.01

CWF 75.53 5.4 23.4

2 D65 74.26 3.25 18.71 5.14 5.21

Minimum

GCR

A-10 75.76 10.18 18.85 4.21 1.85

CWF 74.37 4.38 20.82 3.01 4.40

3 D65 74.09 3.14 18.45 5.31 5.09

Medium

GCR

A-10 75.55 9.93 18.61 4.51 1.74

CWF 74.21 4.24 20.51 3.38 4.38

4 D65 73.99 2.62 17.9 5.98 4.89

Maximum

GCR

A-10 75.37 9.1 18 5.33 1.70

CWF 74.15 3.7 19.94 4.09 4.35

71

5 D65 73.77 2.71 18.22 5.79 4.95

Manual

GCR

A-10 75.18 9.28 18.33 4.99 1.74

CWF 73.93 3.79 20.3 3.84 4.34

Table 9: 7g/m2 only Metamerism Index and ∆E for Rustic Maple

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 74.26 5.21 11.38

Reference

A-10 75.6 7.06 13.16

CWF 75.23 3.69 13.4

2 D65 75.01 1.57 11.45 3.72 4.24

Minimum

GCR

A-10 75.91 7.09 11.15 2.03 1.63

CWF 74.84 2.95 12.64 1.13 3.22

3 D65 75.08 1.45 11.14 3.86 4.01

Medium

GCR

A-10 75.95 6.72 10.88 2.33 1.48

CWF 74.94 2.75 12.31 1.47 3.15

4 D65 74.83 1.05 10.44 4.30 3.57

Maximum

GCR

A-10 75.62 5.79 10.19 3.23 1.27

CWF 74.76 2.21 11.58 2.39 3.01

72

5 D65 74.43 1.1 10.36 4.24 3.56

Manual

GCR

A-10 75.21 5.83 10.12 3.30 1.24

CWF 74.35 2.25 11.48 2.56 3.01

Table 10: 7g/m2 only Spectral Reflectance Values

Wavelength (nm)

Galaxy Oak

Reference Minimum GCR Medium GCR Maximum GCR

380 0.10 0.06 0.06 0.06

390 0.18 0.13 0.13 0.13

400 0.33 0.25 0.25 0.25

410 0.45 0.38 0.38 0.39

420 0.51 0.46 0.46 0.47

430 0.53 0.49 0.49 0.50

440 0.54 0.51 0.51 0.51

450 0.56 0.53 0.53 0.53

460 0.56 0.55 0.55 0.55

470 0.56 0.58 0.58 0.57

480 0.56 0.60 0.60 0.60

490 0.57 0.62 0.62 0.61

500 0.58 0.64 0.63 0.63

510 0.59 0.64 0.63 0.63

520 0.59 0.62 0.62 0.61

73

530 0.60 0.59 0.59 0.59

540 0.61 0.58 0.58 0.58

550 0.61 0.58 0.58 0.58

560 0.62 0.57 0.57 0.58

570 0.62 0.57 0.57 0.58

580 0.63 0.59 0.59 0.59

590 0.64 0.62 0.61 0.61

600 0.64 0.63 0.62 0.62

610 0.64 0.63 0.62 0.62

620 0.64 0.63 0.62 0.62

630 0.64 0.63 0.62 0.62

640 0.64 0.63 0.63 0.63

650 0.64 0.64 0.63 0.63

660 0.64 0.64 0.64 0.63

670 0.64 0.65 0.64 0.63

680 0.64 0.64 0.63 0.63

690 0.63 0.64 0.63 0.63

700 0.63 0.63 0.63 0.63

710 0.64 0.63 0.62 0.63

720 0.63 0.64 0.63 0.63

730 0.63 0.65 0.64 0.64

Wavelength (nm)

Smooth Grey

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.04 0.05 0.05

74

390 0.14 0.08 0.08 0.09

400 0.23 0.15 0.15 0.16

410 0.28 0.21 0.22 0.24

420 0.30 0.25 0.26 0.29

430 0.31 0.27 0.28 0.31

440 0.32 0.29 0.30 0.32

450 0.32 0.32 0.32 0.34

460 0.32 0.34 0.35 0.35

470 0.32 0.38 0.37 0.37

480 0.32 0.41 0.40 0.39

490 0.32 0.43 0.43 0.41

500 0.33 0.45 0.44 0.41

510 0.33 0.44 0.43 0.41

520 0.34 0.40 0.40 0.39

530 0.34 0.35 0.36 0.36

540 0.34 0.33 0.33 0.35

550 0.35 0.33 0.33 0.35

560 0.35 0.31 0.32 0.34

570 0.35 0.30 0.31 0.33

580 0.35 0.33 0.33 0.35

590 0.35 0.37 0.37 0.38

600 0.35 0.39 0.39 0.39

610 0.35 0.39 0.39 0.39

620 0.35 0.39 0.39 0.39

630 0.35 0.40 0.40 0.40

75

640 0.35 0.41 0.41 0.40

650 0.35 0.42 0.42 0.41

660 0.35 0.43 0.43 0.42

670 0.35 0.44 0.44 0.42

680 0.35 0.43 0.43 0.42

690 0.35 0.42 0.42 0.41

700 0.36 0.41 0.41 0.41

710 0.36 0.41 0.41 0.41

720 0.36 0.42 0.42 0.42

730 0.37 0.45 0.45 0.44

Wavelength (nm)

Hunter 655

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.04 0.04 0.04

390 0.13 0.08 0.08 0.08

400 0.19 0.12 0.13 0.13

410 0.22 0.18 0.18 0.18

420 0.23 0.21 0.21 0.21

430 0.25 0.22 0.23 0.23

440 0.27 0.24 0.24 0.25

450 0.28 0.27 0.27 0.27

460 0.29 0.30 0.30 0.30

470 0.29 0.34 0.34 0.34

480 0.29 0.39 0.39 0.39

490 0.30 0.44 0.44 0.43

76

500 0.32 0.47 0.47 0.46

510 0.34 0.48 0.47 0.47

520 0.37 0.45 0.45 0.44

530 0.39 0.40 0.40 0.40

540 0.42 0.39 0.39 0.39

550 0.44 0.39 0.39 0.40

560 0.47 0.39 0.39 0.39

570 0.49 0.39 0.39 0.40

580 0.52 0.44 0.44 0.44

590 0.54 0.52 0.51 0.51

600 0.56 0.56 0.56 0.55

610 0.56 0.58 0.58 0.56

620 0.57 0.59 0.58 0.57

630 0.57 0.59 0.59 0.57

640 0.58 0.60 0.59 0.58

650 0.59 0.60 0.60 0.58

660 0.59 0.61 0.60 0.59

670 0.60 0.61 0.61 0.59

680 0.60 0.61 0.60 0.58

690 0.61 0.60 0.60 0.58

700 0.61 0.60 0.59 0.58

710 0.62 0.60 0.59 0.58

720 0.63 0.60 0.60 0.58

730 0.63 0.62 0.61 0.60

Wavelength (nm) Rustic Maple

77

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.05 0.05 0.05

390 0.15 0.09 0.09 0.09

400 0.23 0.16 0.17 0.16

410 0.29 0.23 0.24 0.24

420 0.31 0.28 0.29 0.29

430 0.33 0.30 0.31 0.31

440 0.34 0.32 0.33 0.33

450 0.36 0.34 0.35 0.35

460 0.36 0.38 0.38 0.38

470 0.36 0.41 0.41 0.41

480 0.37 0.45 0.45 0.44

490 0.37 0.48 0.48 0.47

500 0.38 0.50 0.50 0.48

510 0.40 0.50 0.50 0.48

520 0.41 0.47 0.47 0.46

530 0.42 0.43 0.43 0.43

540 0.44 0.41 0.41 0.41

550 0.45 0.41 0.42 0.42

560 0.46 0.41 0.41 0.41

570 0.49 0.41 0.41 0.41

580 0.51 0.45 0.45 0.45

590 0.52 0.51 0.51 0.50

600 0.53 0.54 0.54 0.52

78

610 0.54 0.55 0.55 0.53

620 0.54 0.56 0.55 0.53

630 0.54 0.56 0.56 0.54

640 0.54 0.57 0.56 0.54

650 0.54 0.58 0.57 0.55

660 0.54 0.59 0.58 0.55

670 0.54 0.59 0.58 0.56

680 0.54 0.58 0.57 0.55

690 0.55 0.58 0.57 0.55

700 0.55 0.57 0.56 0.54

710 0.55 0.57 0.56 0.54

720 0.56 0.58 0.57 0.55

730 0.56 0.60 0.59 0.56

Table 11: 7g/m2 plus Tie Coat Metamerism Index and ∆E for Galaxy Oak

Sr. No Illuminant L a b

Delta E

1976

Metameri

sm

index

1 D65 83.41 0.79 5.08

Reference

A-10 83.85 1.87 5.42

CWF 83.76 0.6 5.92

2 D65 82.7 -2.23 7.36 3.85 2.49

Minimum A-10 82.93 1.07 6.59 1.69 1.00

79

GCR CWF 82.54 -0.75 7.87 2.67 1.78

3 D65 82.96 -2.41 7.39 3.97 2.38

Medium

GCR

A-10 83.18 0.76 6.62 1.77 0.97

CWF 82.84 -0.97 7.94 2.72 1.72

4 D65 82.86 -2.37 7.64 4.10 2.13

Maximum

GCR

A-10 83.1 0.57 6.97 2.16 0.92

CWF 82.83 -1.1 8.28 3.05 1.52

5 D65 82.83 -2.36 7.68 4.13 2.12

Manual

GCR

A-10 83.08 0.58 7.02 2.19 0.93

CWF 82.81 -1.1 8.33 3.10 1.51

Table 12: 7g/m2 plus Tie Coat Metamerism Index and ∆E for Smooth Grey

Sr. No Illuminant L a b

∆E

1976

Metameri

sm

index

1 D65 67.02 0.3 3.05

Reference

A-10 67.27 0.83 3.27

CWF 67.25 0.12 3.56

2 D65 68.69 -2.53 4.5 3.59 4.10

Minimum A-10 68.69 1.79 3.18 1.72 1.62

80

GCR CWF 67.88 -0.21 4.06 0.87 2.87

3 D65 69.19 -1.76 2.94 2.99 3.15

Medium

GCR

A-10 69.17 1.64 1.88 2.49 1.13

CWF 68.5 0.07 2.5 1.64 2.41

4 D65 68.86 -1.52 3.34 2.60 1.65

Maximum

GCR

A-10 68.91 0.44 2.76 1.76 0.53

CWF 68.65 -0.59 3.4 1.58 1.28

5 D65 68.91 -1.5 3.57 2.66 1.69

Manual

GCR

A-10 68.98 0.51 3 1.76 0.59

CWF 68.71 -0.58 3.66 1.62 1.25

Table 13: 7g/m2 plus Tie Coat Metamerism Index and ∆E for Hunter 655

Sr. No Illuminant L a b

∆E

1976

Metameri

sm

index

1 D65 73.88 8.2 20.06

Reference

A-10 76.05 10.79 23.01

CWF 75.53 5.4 23.4

2 D65 74.4 2.98 19.93 5.25 4.79

Minimum A-10 75.93 9.65 20.45 2.80 1.22

81

GCR CWF 74.59 3.89 21.67 2.48 4.30

3 D65 74.56 2.71 19.92 5.53 4.75

Medium

GCR

A-10 76.06 9.3 20.39 3.01 1.24

CWF 74.77 3.64 21.71 2.56 4.29

4 D65 74.45 2.28 19.14 6.02 4.54

Maximum

GCR

A-10 75.86 8.56 19.55 4.12 1.18

CWF 74.69 3.2 20.92 3.42 4.27

5 D65 74.57 2.29 19.14 6.02 4.49

Manual

GCR

A-10 75.98 8.53 19.58 4.11 1.14

CWF 74.82 3.19 20.91 3.40 4.26

Table 14: 7g/m2 plus Tie Coat Metamerism Index and ∆E for Rustic Maple

Sr. No Illuminant L a b

∆E

1976

Metameri

sm

index

1 D65 74.26 5.21 11.38

Reference

A-10 75.6 7.06 13.16

CWF 75.23 3.69 13.4

2 D65 74.72 1.24 10.46 4.10 3.78

Minimum A-10 75.53 6.3 10.32 2.94 0.99

82

GCR CWF 74.51 2.54 11.19 2.59 3.32

3 D65 75.14 1.37 9.84 4.23 3.45

Medium

GCR

A-10 75.93 6.07 9.76 3.56 0.85

CWF 74.98 2.51 10.59 3.06 3.16

4 D65 75.28 0.6 9.4 5.12 3.02

Maximum

GCR

A-10 75.96 4.69 9.27 4.57 0.84

CWF 75.23 1.61 10.21 3.81 2.98

5 D65 75.45 0.57 9.6 5.11 3.03

Manual

GCR

A-10 76.13 4.68 9.48 4.41 0.59

CWF 75.41 1.58 10.11 3.91 3.11

Table 15: 7g/m2 plus Tie Spectral Reflectance Values

Wavelength (nm) Reference Minimum GCR Medium GCR Maximum GCR

380 0.10 0.062 0.06 0.06

390 0.18 0.1257 0.13 0.12

400 0.33 0.2428 0.24 0.24

410 0.45 0.3752 0.38 0.38

420 0.51 0.4511 0.46 0.46

430 0.53 0.4772 0.48 0.48

440 0.54 0.4928 0.50 0.50

450 0.56 0.5111 0.51 0.51

83

460 0.56 0.533 0.54 0.53

470 0.56 0.5575 0.56 0.55

480 0.56 0.5851 0.58 0.58

490 0.57 0.6133 0.61 0.60

500 0.58 0.6331 0.63 0.62

510 0.59 0.6381 0.64 0.63

520 0.59 0.6241 0.62 0.62

530 0.60 0.5991 0.60 0.60

540 0.61 0.5861 0.59 0.59

550 0.61 0.5856 0.59 0.59

560 0.62 0.5774 0.58 0.59

570 0.62 0.5748 0.58 0.59

580 0.63 0.5925 0.59 0.60

590 0.64 0.6182 0.62 0.62

600 0.64 0.6302 0.63 0.62

610 0.64 0.6322 0.63 0.62

620 0.64 0.6321 0.63 0.62

630 0.64 0.6325 0.63 0.62

640 0.64 0.6353 0.63 0.63

650 0.64 0.6396 0.64 0.63

660 0.64 0.6445 0.64 0.63

670 0.64 0.6455 0.64 0.63

680 0.64 0.6424 0.64 0.63

690 0.63 0.6384 0.63 0.63

700 0.63 0.6351 0.63 0.62

84

710 0.64 0.6338 0.63 0.62

720 0.63 0.6389 0.63 0.63

730 0.63 0.6512 0.65 0.64

Wavelength (nm)

Smooth Grey

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.0492 0.05 0.05

390 0.14 0.0905 0.09 0.09

400 0.23 0.16 0.17 0.17

410 0.28 0.236 0.25 0.26

420 0.30 0.2772 0.30 0.31

430 0.31 0.294 0.31 0.32

440 0.32 0.3077 0.33 0.33

450 0.32 0.3229 0.34 0.34

460 0.32 0.3411 0.36 0.35

470 0.32 0.3633 0.37 0.36

480 0.32 0.3901 0.39 0.37

490 0.32 0.4183 0.42 0.38

500 0.33 0.4382 0.43 0.39

510 0.33 0.4382 0.43 0.39

520 0.34 0.4085 0.40 0.39

530 0.34 0.3673 0.37 0.37

540 0.34 0.3452 0.35 0.37

550 0.35 0.3391 0.35 0.37

560 0.35 0.3239 0.33 0.36

85

570 0.35 0.3146 0.32 0.36

580 0.35 0.3352 0.34 0.36

590 0.35 0.3731 0.37 0.38

600 0.35 0.3954 0.39 0.38

610 0.35 0.4013 0.40 0.38

620 0.35 0.4043 0.40 0.38

630 0.35 0.408 0.40 0.38

640 0.35 0.4144 0.41 0.39

650 0.35 0.4242 0.42 0.39

660 0.35 0.435 0.43 0.40

670 0.35 0.4394 0.43 0.40

680 0.35 0.4356 0.43 0.40

690 0.35 0.4286 0.42 0.40

700 0.36 0.4206 0.42 0.39

710 0.36 0.417 0.41 0.39

720 0.36 0.426 0.42 0.40

730 0.37 0.4504 0.44 0.41

Wavelength (nm)

Hunter 655

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.0465 0.05 0.05

390 0.13 0.0798 0.08 0.08

400 0.19 0.1354 0.13 0.14

410 0.22 0.1927 0.19 0.19

420 0.23 0.2239 0.22 0.23

86

430 0.25 0.2375 0.24 0.24

440 0.27 0.2503 0.25 0.25

450 0.28 0.2677 0.27 0.27

460 0.29 0.2917 0.29 0.30

470 0.29 0.3233 0.32 0.33

480 0.29 0.3653 0.36 0.37

490 0.30 0.4158 0.41 0.41

500 0.32 0.4593 0.46 0.45

510 0.34 0.4774 0.48 0.47

520 0.37 0.458 0.46 0.45

530 0.39 0.422 0.42 0.42

540 0.42 0.4063 0.41 0.41

550 0.44 0.4105 0.41 0.42

560 0.47 0.4054 0.41 0.41

570 0.49 0.4079 0.41 0.42

580 0.52 0.4495 0.45 0.45

590 0.54 0.5163 0.52 0.51

600 0.56 0.5631 0.56 0.55

610 0.56 0.5829 0.58 0.57

620 0.57 0.591 0.59 0.58

630 0.57 0.5951 0.59 0.58

640 0.58 0.5999 0.60 0.58

650 0.59 0.6056 0.60 0.59

660 0.59 0.6115 0.61 0.59

670 0.60 0.6132 0.61 0.59

87

680 0.60 0.6101 0.61 0.59

690 0.61 0.6054 0.60 0.59

700 0.61 0.601 0.60 0.58

710 0.62 0.5995 0.60 0.58

720 0.63 0.6052 0.60 0.59

730 0.63 0.62 0.62 0.60

Wavelength (nm)

Rustic Maple

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.0506 0.05 0.05

390 0.15 0.095 0.10 0.10

400 0.23 0.1718 0.17 0.18

410 0.29 0.2532 0.26 0.27

420 0.31 0.2981 0.30 0.32

430 0.33 0.3172 0.32 0.34

440 0.34 0.3319 0.34 0.35

450 0.36 0.3503 0.35 0.37

460 0.36 0.3739 0.38 0.39

470 0.36 0.4026 0.40 0.41

480 0.37 0.4372 0.43 0.44

490 0.37 0.4737 0.47 0.47

500 0.38 0.5002 0.49 0.49

510 0.40 0.5048 0.49 0.49

520 0.41 0.4781 0.47 0.47

530 0.42 0.4385 0.43 0.45

88

540 0.44 0.4202 0.42 0.43

550 0.45 0.422 0.42 0.44

560 0.46 0.4138 0.41 0.43

570 0.49 0.4123 0.41 0.43

580 0.51 0.4471 0.45 0.46

590 0.52 0.5018 0.50 0.50

600 0.53 0.5356 0.53 0.52

610 0.54 0.5472 0.54 0.53

620 0.54 0.5521 0.54 0.53

630 0.54 0.5558 0.54 0.53

640 0.54 0.5615 0.55 0.54

650 0.54 0.569 0.56 0.54

660 0.54 0.5775 0.56 0.55

670 0.54 0.5802 0.57 0.55

680 0.54 0.5767 0.56 0.55

690 0.55 0.5707 0.56 0.54

700 0.55 0.5649 0.55 0.54

710 0.55 0.5624 0.55 0.54

720 0.56 0.5696 0.56 0.55

730 0.56 0.5884 0.58 0.56

Table 16: 10.5 g/m2 plus Tie Coat Metamerism Index and ∆E for Galaxy Oak

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

89

1 D65 83.41 0.79 5.08

Reference

A-10 83.85 1.87 5.42

CWF 83.76 0.6 5.92

2 D65 83.15 -2.03 5.17 2.83 1.97

Minimum

GCR

A-10 83.27 0.64 4.39 1.71 0.59

CWF 82.94 -0.69 5.43 1.61 1.73

3 D65 82.98 -1.93 5.08 2.75 1.85

Medium

GCR

A-10 83.11 0.63 4.35 1.80 0.57

CWF 82.8 -0.67 5.37 1.68 1.64

4 D65 83.22 -1.76 4.9 2.56 1.54

Maximum

GCR

A-10 83.35 0.48 4.27 1.87 0.49

CWF 83.12 -0.69 5.23 1.60 1.43

5 D65 83.22 -1.73 4.96 2.53 1.58

Manual

GCR

A-10 83.36 0.56 4.33 1.77 0.50

CWF 83.11 -0.64 5.3 1.53 1.45

Table 17: 10.5 g/m2 plus Tie Coat Metamerism Index and ∆E for Smooth Grey

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 67.02 0.3 3.05

90

Reference

A-10 67.27 0.83 3.27

CWF 67.25 0.12 3.56

2 D65 69.39 -2 4.5 3.61 3.94

Minimum

GCR

A-10 69.45 2.21 3.33 2.58 1.66

CWF 68.65 0.13 4.13 1.51 2.66

3 D65 69.09 -2.06 4.64 3.52 3.55

Medium

GCR

A-10 69.16 1.77 3.57 2.13 1.48

CWF 68.46 -0.14 4.41 1.50 2.39

4 D65 69.39 -1.23 2.63 2.85 1.70

Maximum

GCR

A-10 69.43 0.77 2.02 2.50 0.52

CWF 69.1 -0.26 2.57 2.13 1.38

5 D65 69.83 -1.11 2.75 3.16 1.68

Manual

GCR

A-10 69.89 0.89 2.18 2.84 0.53

CWF 69.56 -0.17 2.72 2.48 1.34

Table 18: 10.5 g/m2 plus Tie Coat Metamerism Index and ∆E for Hunter 655

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 73.88 8.2 20.06

Reference A-10 76.05 10.79 23.01

91

CWF 75.53 5.4 23.4

2 D65 74.56 2.86 18.62 5.57 4.58

Minimum

GCR

A-10 76.01 9.23 19.09 4.22 1.59

CWF 74.14 3.75 20.31 3.77 4.54

3 D65 74.24 2.74 18.8 5.62 4.55

Medium

GCR

A-10 75.68 9.08 19.27 4.13 1.13

CWF 74.44 3.62 20.53 3.55 4.27

4 D65 73.64 2.48 18.54 5.92 4.43

Maximum

GCR

A-10 75.04 8.63 18.97 4.69 1.16

CWF 73.87 3.34 20.31 4.07 4.23

5 D65 74.83 2.11 18.31 6.41 4.37

Manual

GCR

A-10 76.18 8.14 18.69 5.07 1.16

CWF 75.07 3.01 20.05 4.14 4.27

Table 19: 10.5 g/m2 plus Tie Coat Metamerism Index and ∆E for Rustic Maple

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 74.26 5.21 11.38

Reference

A-10 75.6 7.06 13.16

CWF 75.23 3.69 13.4

92

2 D65 75.27 1.04 12.68 4.48 4.02

Minimum

GCR

A-10 76.19 6.41 12.57 1.06 1.33

CWF 75.18 2.33 13.73 1.40 3.16

3 D65 74.95 0.94 12.33 4.43 3.82

Medium

GCR

A-10 75.83 6.08 12.23 1.37 1.20

CWF 74.89 2.15 13.37 1.58 3.08

4 D65 75.33 0.28 10.92 5.07 3.33

Maximum

GCR

A-10 76.07 4.76 10.74 3.37 0.99

CWF 75.31 1.41 11.89 2.74 3.02

5 D65 75.39 0.42 11.09 4.93 3.31

Manual

GCR

A-10 76.15 4.9 10.95 3.14 0.99

CWF 75.39 1.51 12.1 2.54 2.96

Table 20: 10.5 g/m2 plus Tie Spectral Reflectance Values

Wavelength (nm)

Galaxy Oak

Reference Minimum GCR Medium GCR Maximum GCR

380 0.10 0.0518 0.05 0.05

390 0.18 0.1204 0.12 0.12

400 0.33 0.2477 0.25 0.25

410 0.45 0.3942 0.40 0.40

93

420 0.51 0.4793 0.48 0.49

430 0.53 0.5064 0.51 0.52

440 0.54 0.5207 0.52 0.53

450 0.56 0.5367 0.54 0.55

460 0.56 0.5556 0.55 0.56

470 0.56 0.5757 0.57 0.58

480 0.56 0.5972 0.59 0.60

490 0.57 0.6188 0.61 0.61

500 0.58 0.6334 0.63 0.63

510 0.59 0.6356 0.63 0.63

520 0.59 0.6215 0.62 0.62

530 0.60 0.5972 0.59 0.60

540 0.61 0.5841 0.58 0.59

550 0.61 0.5832 0.58 0.59

560 0.62 0.5747 0.57 0.59

570 0.62 0.5712 0.57 0.59

580 0.63 0.5868 0.59 0.60

590 0.64 0.6103 0.61 0.61

600 0.64 0.62 0.62 0.62

610 0.64 0.6205 0.62 0.62

620 0.64 0.62 0.62 0.62

630 0.64 0.6202 0.62 0.62

640 0.64 0.6234 0.62 0.62

650 0.64 0.6279 0.62 0.63

660 0.64 0.6334 0.63 0.63

94

670 0.64 0.6343 0.63 0.63

680 0.64 0.6314 0.63 0.63

690 0.63 0.6274 0.62 0.62

700 0.63 0.6235 0.62 0.62

710 0.64 0.6229 0.62 0.62

720 0.63 0.628 0.62 0.63

730 0.63 0.641 0.64 0.64

Wavelength (nm)

Smooth Grey

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.0353 0.04 0.04

390 0.14 0.0794 0.08 0.09

400 0.23 0.1537 0.15 0.17

410 0.28 0.2313 0.23 0.26

420 0.30 0.2759 0.28 0.31

430 0.31 0.2943 0.29 0.33

440 0.32 0.3075 0.30 0.34

450 0.32 0.3233 0.32 0.35

460 0.32 0.3422 0.33 0.36

470 0.32 0.3648 0.35 0.37

480 0.32 0.3914 0.38 0.38

490 0.32 0.4192 0.40 0.39

500 0.33 0.4385 0.42 0.40

510 0.33 0.4383 0.42 0.40

520 0.34 0.4088 0.40 0.39

95

530 0.34 0.3678 0.36 0.37

540 0.34 0.3458 0.34 0.36

550 0.35 0.3403 0.34 0.36

560 0.35 0.3253 0.33 0.35

570 0.35 0.3156 0.32 0.35

580 0.35 0.3365 0.34 0.36

590 0.35 0.3752 0.37 0.38

600 0.35 0.3978 0.39 0.38

610 0.35 0.4035 0.39 0.38

620 0.35 0.4066 0.40 0.39

630 0.35 0.4106 0.40 0.39

640 0.35 0.4174 0.40 0.39

650 0.35 0.4275 0.41 0.40

660 0.35 0.439 0.42 0.40

670 0.35 0.4432 0.43 0.41

680 0.35 0.4394 0.42 0.41

690 0.35 0.4325 0.42 0.40

700 0.36 0.424 0.41 0.40

710 0.36 0.4204 0.41 0.40

720 0.36 0.4302 0.42 0.41

730 0.37 0.4552 0.44 0.42

Wavelength (nm)

Smooth Grey

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.0352 0.04 0.04

96

390 0.13 0.0723 0.07 0.07

400 0.19 0.1329 0.13 0.13

410 0.22 0.1932 0.19 0.19

420 0.23 0.2269 0.23 0.22

430 0.25 0.242 0.24 0.23

440 0.27 0.2551 0.25 0.25

450 0.28 0.2734 0.27 0.26

460 0.29 0.2977 0.30 0.29

470 0.29 0.3287 0.33 0.32

480 0.29 0.3695 0.37 0.36

490 0.30 0.4176 0.41 0.40

500 0.32 0.4576 0.45 0.44

510 0.34 0.4735 0.47 0.46

520 0.37 0.4543 0.45 0.44

530 0.39 0.4193 0.42 0.41

540 0.42 0.4038 0.40 0.40

550 0.44 0.4082 0.41 0.40

560 0.47 0.4039 0.40 0.40

570 0.49 0.4067 0.41 0.40

580 0.52 0.4474 0.45 0.44

590 0.54 0.5124 0.51 0.50

600 0.56 0.5572 0.55 0.54

610 0.56 0.5758 0.57 0.55

620 0.57 0.5832 0.58 0.56

630 0.57 0.5871 0.58 0.56

97

640 0.58 0.5917 0.58 0.57

650 0.59 0.597 0.59 0.57

660 0.59 0.6031 0.60 0.58

670 0.60 0.6046 0.60 0.58

680 0.60 0.6016 0.59 0.57

690 0.61 0.5971 0.59 0.57

700 0.61 0.5932 0.59 0.57

710 0.62 0.5923 0.59 0.57

720 0.63 0.5976 0.59 0.57

730 0.63 0.6114 0.60 0.58

Wavelength (nm)

Smooth Grey

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.041 0.04 0.04

390 0.15 0.0833 0.08 0.09

400 0.23 0.1561 0.16 0.17

410 0.29 0.2313 0.24 0.26

420 0.31 0.2742 0.28 0.31

430 0.33 0.2923 0.30 0.32

440 0.34 0.3077 0.31 0.34

450 0.36 0.3268 0.33 0.35

460 0.36 0.3525 0.35 0.38

470 0.36 0.3835 0.38 0.40

480 0.37 0.4204 0.42 0.43

490 0.37 0.46 0.46 0.46

98

500 0.38 0.4892 0.48 0.48

510 0.40 0.4965 0.49 0.49

520 0.41 0.4727 0.47 0.47

530 0.42 0.435 0.43 0.45

540 0.44 0.4179 0.42 0.43

550 0.45 0.4204 0.42 0.44

560 0.46 0.4133 0.41 0.43

570 0.49 0.413 0.41 0.43

580 0.51 0.4481 0.45 0.46

590 0.52 0.5029 0.50 0.50

600 0.53 0.5368 0.53 0.53

610 0.54 0.5486 0.54 0.53

620 0.54 0.5533 0.54 0.54

630 0.54 0.5567 0.55 0.54

640 0.54 0.562 0.55 0.54

650 0.54 0.5689 0.56 0.55

660 0.54 0.5767 0.57 0.55

670 0.54 0.579 0.57 0.56

680 0.54 0.5758 0.56 0.55

690 0.55 0.5706 0.56 0.55

700 0.55 0.5652 0.55 0.55

710 0.55 0.5635 0.55 0.55

720 0.56 0.5702 0.56 0.55

730 0.56 0.5874 0.58 0.57

99

Table 21: 10.5 g/m2 Metamerism Index and ∆E for Galaxy Oak

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 83.41 0.79 5.08

Reference

A-10 83.85 1.87 5.42

CWF 83.76 0.6 5.92

2 D65 83.12 -2.23 7.11 3.65 2.55

Minimum

GCR

A-10 83.34 1.08 6.24 1.25 1.17

CWF 82.96 -0.75 7.72 2.39 1.76

3 D65 82.76 -1.76 7.25 3.41 2.51

Medium

GCR

A-10 83.04 1.57 6.5 1.38 1.20

CWF 82.63 -0.38 7.93 2.51 1.65

4 D65 83.03 -1.74 7.23 3.34 2.26

Maximum

GCR

A-10 83.31 1.35 6.56 1.36 1.09

CWF 82.96 -0.5 7.94 2.44 1.50

5 D65 83.19 -1.77 7.14 3.29 2.22

Manual

GCR

A-10 83.47 1.28 6.46 1.25 1.06

CWF 83.13 -0.53 7.84 2.32 1.49

Table 22: 10.5 g/m2 Metamerism Index and ∆E for Smooth Grey

100

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 67.02 0.3 3.05

Reference

A-10 67.27 0.83 3.27

CWF 67.25 0.12 3.56

2 D65 69.47 -0.88 4.64 3.15 4.44

Minimum

GCR

A-10 69.66 3.84 3.4 3.85 2.30

CWF 68.73 1.27 4.7 2.19 2.56

3 D65 69.42 -0.71 4.5 2.98 3.98

Medium

GCR

A-10 69.63 3.59 3.43 3.63 2.09

CWF 68.78 1.19 4.62 2.15 2.29

4 D65 69.88 -0.95 3.55 3.16 2.50

Maximum

GCR

A-10 70.01 1.88 2.79 2.97 1.17

CWF 69.52 0.29 3.69 2.28 1.58

5 D65 70.21 -1.07 3.55 3.51 2.47

Manual

GCR

A-10 70.33 1.72 2.77 3.23 1.14

CWF 69.86 0.17 3.69 2.61 1.58

Table 23: 10.5 g/m2 Metamerism Index and ∆E for Hunter 655

101

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 73.88 8.2 20.06

Reference

A-10 76.05 10.79 23.01

CWF 75.53 5.4 23.4

2 D65 74.36 3.58 17.23 5.44 4.94

Minimum

GCR

A-10 75.81 10.22 17.44 5.60 1.62

CWF 74.44 4.61 19.19 4.42 4.36

3 D65 74.11 3.57 17.69 5.21 4.95

Medium

GCR

A-10 75.58 10.23 17.92 5.14 1.65

CWF 74.22 4.58 19.71 4.00 4.32

4 D65 74.05 3.2 17.79 5.49 4.94

Maximum

GCR

A-10 75.49 9.81 17.97 5.16 1.69

CWF 74.18 4.25 19.84 3.98 4.34

5 D65 74.49 3.01 17.42 5.85 4.88

Manual

GCR

A-10 75.89 9.51 17.56 5.60 1.65

CWF 74.62 4.06 19.42 4.30 4.35

Table 24: 10.5 g/m2 Metamerism Index and ∆E for Rustic Maple

102

Sr. No Illuminant L a b

∆E

1976

Metamerism

index

1 D65 74.26 5.21 11.38

Reference

A-10 75.6 7.06 13.16

CWF 75.23 3.69 13.4

2 D65 75.16 1.62 11.33 3.70 4.19

Minimum

GCR

A-10 76.06 7.09 11.04 2.17 1.61

CWF 74.99 2.97 12.52 1.16 3.20

3 D65 75.09 1.72 11.12 3.60 3.96

Medium

GCR

A-10 75.99 6.97 10.92 2.28 1.48

CWF 74.97 2.96 12.32 1.33 3.08

4 D65 75.29 0.85 10.85 4.51 3.72

Maximum

GCR

A-10 76.08 5.73 10.55 2.97 1.37

CWF 75.21 2.09 12.04 2.10 3.07

5 D65 75.55 0.8 10.75 4.64 3.68

Manual

GCR

A-10 76.32 5.62 10.44 3.16 1.36

CWF 75.47 2.02 11.93 2.24 3.05

Table 25: 10.5 g/m2 Spectral Reflectance Values

Wavelength (nm) Galaxy Oak

103

Reference Minimum GCR Medium GCR Maximum GCR

380 0.10 0.0494 0.05 0.05

390 0.18 0.1165 0.12 0.12

400 0.33 0.232 0.23 0.24

410 0.45 0.365 0.36 0.37

420 0.51 0.4416 0.44 0.45

430 0.53 0.4694 0.47 0.48

440 0.54 0.4892 0.49 0.50

450 0.56 0.5119 0.51 0.52

460 0.56 0.5377 0.53 0.54

470 0.56 0.5632 0.56 0.56

480 0.56 0.5899 0.59 0.59

490 0.57 0.6158 0.61 0.61

500 0.58 0.6325 0.63 0.62

510 0.59 0.6345 0.63 0.63

520 0.59 0.6183 0.61 0.62

530 0.60 0.592 0.59 0.59

540 0.61 0.5788 0.58 0.58

550 0.61 0.5796 0.58 0.59

560 0.62 0.5727 0.57 0.58

570 0.62 0.5714 0.57 0.58

580 0.63 0.5909 0.59 0.60

590 0.64 0.6175 0.62 0.62

600 0.64 0.6291 0.63 0.63

104

610 0.64 0.6304 0.63 0.64

620 0.64 0.6303 0.63 0.63

630 0.64 0.6312 0.64 0.64

640 0.64 0.6344 0.64 0.64

650 0.64 0.6395 0.64 0.64

660 0.64 0.6453 0.65 0.64

670 0.64 0.6461 0.65 0.65

680 0.64 0.6425 0.64 0.64

690 0.63 0.6384 0.64 0.64

700 0.63 0.635 0.64 0.64

710 0.64 0.6337 0.64 0.64

720 0.63 0.6401 0.64 0.64

730 0.63 0.6528 0.65 0.65

Wavelength (nm)

Smooth Grey

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.038 0.04 0.04

390 0.14 0.08 0.08 0.09

400 0.23 0.1477 0.15 0.17

410 0.28 0.2192 0.22 0.25

420 0.30 0.2607 0.26 0.30

430 0.31 0.2816 0.28 0.32

440 0.32 0.3003 0.30 0.33

450 0.32 0.3242 0.32 0.34

460 0.32 0.3518 0.35 0.36

105

470 0.32 0.3814 0.38 0.38

480 0.32 0.4116 0.40 0.39

490 0.32 0.437 0.43 0.41

500 0.33 0.4496 0.44 0.42

510 0.33 0.4413 0.43 0.41

520 0.34 0.4029 0.40 0.40

530 0.34 0.3537 0.35 0.37

540 0.34 0.331 0.33 0.36

550 0.35 0.3311 0.33 0.36

560 0.35 0.3189 0.32 0.35

570 0.35 0.3126 0.32 0.35

580 0.35 0.3437 0.35 0.36

590 0.35 0.3916 0.39 0.39

600 0.35 0.4154 0.41 0.40

610 0.35 0.4196 0.41 0.40

620 0.35 0.4224 0.41 0.40

630 0.35 0.4272 0.42 0.41

640 0.35 0.4356 0.43 0.41

650 0.35 0.4481 0.44 0.42

660 0.35 0.462 0.45 0.43

670 0.35 0.4671 0.46 0.43

680 0.35 0.462 0.45 0.43

690 0.35 0.4538 0.44 0.42

700 0.36 0.4434 0.43 0.42

710 0.36 0.4384 0.43 0.42

106

720 0.36 0.45 0.44 0.43

730 0.37 0.4792 0.47 0.44

Wavelength (nm)

Hunter 655

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.0365 0.04 0.04

390 0.13 0.0721 0.07 0.07

400 0.19 0.1287 0.12 0.12

410 0.22 0.1846 0.18 0.18

420 0.23 0.2174 0.21 0.21

430 0.25 0.2359 0.23 0.23

440 0.27 0.2548 0.25 0.25

450 0.28 0.2809 0.27 0.27

460 0.29 0.3141 0.31 0.31

470 0.29 0.3525 0.35 0.34

480 0.29 0.3966 0.39 0.39

490 0.30 0.4403 0.44 0.43

500 0.32 0.4695 0.46 0.46

510 0.34 0.4731 0.47 0.46

520 0.37 0.4429 0.44 0.44

530 0.39 0.3989 0.40 0.40

540 0.42 0.3813 0.38 0.38

550 0.44 0.3892 0.39 0.39

560 0.47 0.3866 0.38 0.38

570 0.49 0.3922 0.39 0.39

107

580 0.52 0.4427 0.44 0.44

590 0.54 0.5167 0.51 0.51

600 0.56 0.5633 0.56 0.55

610 0.56 0.5811 0.58 0.57

620 0.57 0.5884 0.58 0.57

630 0.57 0.5928 0.59 0.58

640 0.58 0.5982 0.59 0.58

650 0.59 0.6053 0.60 0.59

660 0.59 0.6128 0.60 0.60

670 0.60 0.6144 0.61 0.60

680 0.60 0.6106 0.60 0.59

690 0.61 0.606 0.60 0.59

700 0.61 0.6012 0.59 0.59

710 0.62 0.5995 0.59 0.58

720 0.63 0.6072 0.60 0.59

730 0.63 0.623 0.61 0.61

Wavelength (nm)

Rustic Maple

Reference Minimum GCR Medium GCR Maximum GCR

380 0.09 0.041 0.04 0.04

390 0.15 0.0847 0.09 0.09

400 0.23 0.1562 0.16 0.16

410 0.29 0.2325 0.24 0.24

420 0.31 0.2759 0.28 0.29

430 0.33 0.2972 0.30 0.31

108

440 0.34 0.3177 0.32 0.33

450 0.36 0.344 0.35 0.35

460 0.36 0.3754 0.38 0.38

470 0.36 0.4101 0.41 0.41

480 0.37 0.4476 0.44 0.45

490 0.37 0.4824 0.48 0.48

500 0.38 0.5037 0.50 0.50

510 0.40 0.5028 0.50 0.50

520 0.41 0.4711 0.47 0.47

530 0.42 0.4272 0.43 0.44

540 0.44 0.4082 0.41 0.42

550 0.45 0.4136 0.41 0.43

560 0.46 0.4085 0.41 0.42

570 0.49 0.4103 0.41 0.42

580 0.51 0.4525 0.45 0.46

590 0.52 0.5132 0.51 0.51

600 0.53 0.5479 0.54 0.53

610 0.54 0.5588 0.55 0.54

620 0.54 0.5634 0.55 0.55

630 0.54 0.5676 0.56 0.55

640 0.54 0.5737 0.56 0.55

650 0.54 0.5826 0.57 0.56

660 0.54 0.5917 0.58 0.57

670 0.54 0.5942 0.58 0.57

680 0.54 0.5901 0.58 0.57

109

690 0.55 0.5843 0.57 0.56

700 0.55 0.5776 0.57 0.56

710 0.55 0.5754 0.57 0.56

720 0.56 0.584 0.57 0.56

730 0.56 0.6037 0.59 0.58

Table 26: Data Table for ANOVA

Input Output: Metamerism Index (D65 & CWF)

Trials

Factor 1:

Release

Coat

Weight

(g/m2)

Factor

2: Use

of Tie

Coat

Factor 3: GCR

levels

Galaxy

Oak

Smooth

Grey

Hunter

655

Rustic

Maple

1 7 Yes Minimum 2.49 4.1 4.79 3.78

2 10.5 No Medium+ 2.51 3.98 4.95 3.96

3 7 Yes Maximum 2.13 1.65 4.54 3.02

4 10.5 No Minimum 2.55 4.44 4.94 4.19

5 7 Yes Medium+ 2.38 3.15 4.75 3.45

6 10.5 No Maximum 2.26 2.5 4.94 3.72

7 7 No Minimum 2.24 4.72 5.21 4.24

8 10.5 Yes Medium+ 1.85 3.55 4.55 3.82

9 7 No Maximum 1.88 2.66 4.89 3.57

110

10 10.5 Yes Minimum 1.97 3.94 4.58 4.02

11 7 No Medium+ 2.1 4.09 5.09 4.01

12 10.5 Yes Maximum 1.54 1.7 4.43 3.33