ISO 2846-1:2006
(Main)Graphic technology — Colour and transparency of printing ink sets for four-colour printing — Part 1: Sheet-fed and heat-set web offset lithographic printing
Graphic technology — Colour and transparency of printing ink sets for four-colour printing — Part 1: Sheet-fed and heat-set web offset lithographic printing
ISO 2846-1:2006 specifies the colour and transparency characteristics that have to be met by each ink in a process colour ink set intended for proof and production printing using offset lithography. The specified printing conditions (which use a laboratory printability tester), the defined substrate and a method for testing to ensure conformance are also defined. Characteristics are specified for inks used for sheet-fed, heat-set web and radiation-curing processes.
Technologie graphique — Couleur et transparence des gammes d'encre d'impression en quadrichromie — Partie 1: Impression lithographique offset sur feuilles et à chaud
Grafična tehnologija - Barvni učinki in prozornost sklanih (procesnih) tiskarskih barv - 1. del: Ofsetni tisk na pole in ofsetni tisk na rotacijah z vročim sušenjem (heat-set)
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INTERNATIONAL ISO
STANDARD 2846-1
Second edition
2006-11-15
Graphic technology — Colour and
transparency of printing ink sets for four-
colour printing —
Part 1:
Sheet-fed and heat-set web offset
lithographic printing
Technologie graphique — Couleur et transparence des gammes
d'encre d'impression en quadrichromie —
Partie 1: Impression lithographique offset sur feuilles et à chaud
Reference number
ISO 2846-1:2006(E)
©
ISO 2006
---------------------- Page: 1 ----------------------
ISO 2846-1:2006(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2006
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2006 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 2846-1:2006(E)
Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Test method. 2
4.1 Procedure . 2
4.2 Test print preparation. 2
4.3 Colour measurement procedures . 3
5 Requirements for colour, transparency and ink film thickness range. 4
5.1 General. 4
5.2 Colorimetric values. 4
5.3 Transparency characteristics. 4
5.4 Ink film thickness. 4
Annex A (normative) Reference substrate . 5
Annex B (informative) Extended explanation of the test procedures, including examples . 6
Annex C (informative) Spectral data. 10
Annex D (informative) Tristimulus values for 8°:di geometry and illuminant D65 . 13
Bibliography . 15
© ISO 2006 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO 2846-1:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 2846-1 was prepared by Technical Committee ISO/TC 130, Graphic technology.
This second edition cancels and replaces the first edition (ISO 2846-1:1997), of which subclauses 4.2 and 5.2
and Annex D have been technically revised. Some very minor changes have been made for the purposes of
simplification, and an effort has been made to clarify and update this document in some places. Clauses 4
and 5 have been interchanged with each other. In addition, the test-print preparation requirements have been
deleted and referenced to ISO 2834-1. Annex B, describing the history of the development of the colour
standard, has been removed and Annex E relettered to Annex B.
ISO 2846 consists of the following parts, under the general title Graphic technology — Colour and
transparency of printing ink sets for four-colour printing:
⎯ Part 1: Sheet-fed and heat-set web offset lithographic printing
⎯ Part 2: Coldset offset lithographic printing
⎯ Part 3: Publication gravure printing
⎯ Part 4: Screen printing
⎯ Part 5: Flexographic printing
iv © ISO 2006 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 2846-1:2006(E)
Introduction
This part of ISO 2846 defines the colour and transparency of lithographic printing inks. Different sets of inks
(both for proof and production printing) conforming to this part of ISO 2846 will produce a similar colour when
printed on the same substrate at the appropriate film thickness. This enables colour separations for offset-
lithographic printing to be based on known colour references and simplifies the task of consistently printing the
same images in multiple printing sites.
It should be noted that the colorimetric characteristics specified can only be obtained when the inks are
printed on the reference substrate. However, the similarity of two inks on a reference substrate generally
ensures similarity on another substrate, and it is this similarity that has enabled industry specifications or
[1]
standards such as ISO 12647-2 , which specifies the colour of these inks on other substrates, to be
developed.
The colour specified in the previous edition of this part of ISO 2846 was based on extensive measurements of
commercial ink sets made in Europe, Japan and the USA. A working group of ISO/TC 130 process control
and material experts examined data sets from various countries at the time that edition was prepared and
found that a single set of colour coordinates could adequately represent all three proposals within reasonable
tolerances. In addition, they found that the transparency of various inks could also be adequately represented
by a new method of evaluation. A review undertaken prior to the revision of this edition suggested that there
had been little change in the colour and transparency of the inks commercially available and that the
characteristics specified in this part of ISO 2846 could be reconfirmed.
© ISO 2006 – All rights reserved v
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 2846-1:2006(E)
Graphic technology — Colour and transparency of printing ink
sets for four-colour printing —
Part 1:
Sheet-fed and heat-set web offset lithographic printing
1 Scope
This part of ISO 2846 specifies the colour and transparency characteristics that have to be met by each ink in
a process colour ink set intended for proof and production printing using offset lithography. The specified
printing conditions (which use a laboratory printability tester), the defined substrate and a method for testing to
ensure conformance are also defined. Characteristics are specified for inks used for sheet-fed, heat-set web
and radiation-curing processes.
This part of ISO 2846 does not apply to fluorescent inks and it does not specify pigments (or spectral
characteristics — except informatively) in order not to preclude developments which may enable different
pigment combinations to be used advantageously while still achieving the colorimetric requirements specified
in this part of ISO 2846.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 535, Paper and board — Determination of water absorptiveness — Cobb method
ISO 536, Paper and board — Determination of grammage
ISO 2144, Paper, board and pulps — Determination of residue (ash) on ignition at 900 °C
ISO 2834-1, Graphic technology — Laboratory preparation of test prints — Part 1: Paste inks
ISO 6588-1, Paper, board and pulps — Determination of pH of aqueous extracts — Part 1: Cold extraction
ISO 8254-1, Paper and board — Measurement of specular gloss — Part 1: 75° gloss with a converging beam,
TAPPI method
ISO 8791-4, Paper and board — Determination of roughness/smoothness (air leak methods) — Part 4: Print-
surf method
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images
ANSI CGATS.5:2003, Graphic technology — Spectral measurement and colorimetric computation for graphic
arts images
© ISO 2006 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO 2846-1:2006(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
standard ink
ink intended for four-colour printing which, when printed on the reference substrate and within the applicable
range of ink film thicknesses, complies to the colorimetric and transparency specifications of this part of
ISO 2846
3.2
transparency
ability of an ink film to transmit light
NOTE It is generally expressed as some measure of the unwanted scattering.
3.3
transparency measurement value
T
reciprocal of the slope of the regression line between ink film thickness and colour difference for overprints of
chromatic inks over black substrate
4 Test method
4.1 Procedure
Colorimetric conformance shall be verified by printing each ink on the reference substrate, described in
Annex A, at a range of ink film thicknesses. The colours of the resultant test prints shall be measured and the
colour difference determined between the sample and the pertinent value given in Table 1. If at least one of
these samples has a smaller colour difference than that specified in 5.2, the ink conforms colorimetrically to
this part of ISO 2846.
NOTE It is often more convenient to determine the colorimetric conformance of an ink graphically. This is achieved
by calculating the colour difference (∆E* ) from the values in Table 1 for each of the prints made and plotting this against
ab
the ink film thickness. The ink conforms if the resultant curve shows a pronounced minimum which is below the ∆E* value
ab
specified in Table 1. (See Annex B for further information.)
Transparency value, T, shall be determined by printing each of the chromatic process inks on to a black
substrate meeting the requirements of 4.2.2, at a range of ink film thicknesses. The colour difference, ∆E* , is
ab
determined for each sample between the overprinted and unprinted black substrate. The gradient of the linear
regression of ink film thickness on colour difference shall be determined. An ink conforms to the transparency
requirements of this part of ISO 2846 if the reciprocal of the gradient is negative, or greater than the value
specified. (See Annex B for further information.)
The gradient of the regression equation may be determined directly from the data obtained. However, it is
recommended that it be obtained from a graphical plot of the values of ∆E* against ink film thickness. Such a
ab
plot enables any unexpected characteristics of the data to be easily visualised. (See Annex B for further
information.)
If one or more printed samples of each ink conform to the colorimetric values within the tolerances specified,
and the ink also meets the transparency criteria, that ink can be said to comply to this part of ISO 2846.
4.2 Test print preparation
4.2.1 Prints for colorimetric evaluation
For each of the inks to be evaluated, a number of test prints shall be made, each produced at a different ink
film thickness, according to the conditions specified in ISO 2834-1.
2 © ISO 2006 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 2846-1:2006(E)
They shall be made on the reference substrate specified in Annex A. The range of ink film thicknesses
produced shall encompass that specified for the process for which the ink is intended. (See 5.4.)
4.2.2 Prints for transparency evaluation
The test prints for transparency evaluation shall be produced by printing the inks to be tested on a black
substrate such that a minimum of four samples is achieved, each with a different ink film thickness. The
printing shall be undertaken as described in ISO 2834-1. The range of ink film thicknesses achieved should at
least cover that defined in 5.4.
The black substrate shall have a lightness, L*, less than 6 when determined in accordance with ISO 13655
(with the exception that a white backing shall be used when measuring the print; see 4.3).
Although in principle it is possible for the user to produce, themselves, the black substrate by printing, it is
difficult to ensure that the lightness is sufficiently low without adversely affecting the gloss and printing
properties of the substrate. It is usually preferable to use a black substrate or a substrate pre-printed
commercially. However, if it is necessary to print the black, the recommendations given in Annex B should be
1)
followed. Appropriate substrates are the contrast card or the contrast strip .
4.2.3 Drying of test prints
Prior to colour measurement, all samples shall be thoroughly dry. Inks formulated for oxidation drying shall be
left for at least 24 h, those formulated for radiation curing shall be dried with an appropriate radiation source
within the appropriate time and heat-set inks shall be heat dried with appropriate drying equipment.
NOTE Be aware that the appropriate time for radiation curing inks can be down to parts of a second only.
4.3 Colour measurement procedures
Test prints shall be measured in accordance with ISO 13655, except that a white backing which is in
conformance with ANSI CGATS.5 shall be used.
Conforming to ISO 13655 means that samples shall be measured spectrally, with a 0°:45°a or 45°a:0°
geometry instrument, and for calculation of CIELAB colour values the CIE 1931 (2°) standard colorimetric
observer data is used together with CIE standard illuminant D50; see Reference [3]. Where spectral data is
obtained at wavelength intervals greater than 5 nm, the weighting functions for the standard colorimetric
observer specified in ISO 13655 are used.
For calculating the colour difference from the reference values, the CIE 1976 colour difference, ∆E* , shall be
ab
used.
NOTE 1 ISO 13655 is currently under revision and it is the intent of the committee to add a white backing condition
identical to that of ANSI CGATS.5.
NOTE 2 For the comparison of measurements, it is useful to record the following details:
⎯ the ink designation and batch number;
⎯ the ink layer thicknesses;
⎯ the substrate used;
⎯ the printability tester used and the settings used on the tester (speed, force, printing forme);
⎯ environmental conditions (lab temperature and relative humidity);
⎯ spectrophotometer used;
⎯ any deviations from this part of ISO 2846.
1) Leneta paper or card (No. 105 C) which may be purchased from Leneta Corp., Mahwah, NJ, USA; contrast strip:
comparison test strips Ka APCO C with contrast band (several widths) which may be purchased from IGT Testing
Systems, Amsterdam, The Netherlands. These products are examples of suitable products available commercially. This
information is given for the convenience of users of this part of ISO 2846 and does not constitute an endorsement by ISO
of these products.
© ISO 2006 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO 2846-1:2006(E)
5 Requirements for colour, transparency and ink film thickness range
5.1 General
For an ink to conform to this part of ISO 2846 it shall meet the specifications for colour defined in 5.2, and the
specification for transparency defined in 5.3, at some ink film thickness within the range specified in 5.4.
5.2 Colorimetric values
When printed in accordance with Clause 4, an ink shall produce a colour that falls within the defined colour
difference tolerances, ∆E* , from the L*, a*, b* values specified in Table 1.
ab
Table 1 — Colorimetric values for 0°:45°a geometry, illuminant D50, 2° observer
a a
CIELAB values Tolerances
Ink
L* a* b* ∆E* ∆a* ∆b* L*
ab
Yellow 91,0 −5,1 95,0 4,0 — — —
Magenta 50,0 76,0 4,0 — — —
−3,0
Cyan 57,0 −39,2 −46,0 4,0 — — —
b
Black 18,0 0,8 0,0 — ± 1,5 ± 3,0
18,0
a
Parameters L*, a*, b*, ∆E* ,∆a*and ∆b* are defined in ISO 13655.
ab
b
For black, there is no symmetrical tolerance for L* but an upper limit.
NOTE 1 Typical spectral data for inks conforming to this part of ISO 2846 are provided in Annex C. Reference spectral
data for 8°:di or di:8° geometry are also included in Annex C.
NOTE 2 Reference data for tristimulus values calculated from the CIE 1931 (2°) standard colorimetric observer,
together with CIE illuminant D65, are included in A
...
SLOVENSKI STANDARD
SIST ISO 2846-1:2008
01-januar-2008
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Graphic technology - Colour and transparency of printing ink sets for four-colour printing
- Part 1: Sheet-fed and heat-set web offset lithographic printing
Ta slovenski standard je istoveten z: ISO 2846-1:2006
ICS:
37.100.01 *UDILþQDWHKQRORJLMDQD Graphic technology in
VSORãQR general
87.080 Barvila. Tiskarske barve Inks. Printing inks
SIST ISO 2846-1:2008 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 2846-1:2008
---------------------- Page: 2 ----------------------
SIST ISO 2846-1:2008
INTERNATIONAL ISO
STANDARD 2846-1
Second edition
2006-11-15
Graphic technology — Colour and
transparency of printing ink sets for four-
colour printing —
Part 1:
Sheet-fed and heat-set web offset
lithographic printing
Technologie graphique — Couleur et transparence des gammes
d'encre d'impression en quadrichromie —
Partie 1: Impression lithographique offset sur feuilles et à chaud
Reference number
ISO 2846-1:2006(E)
©
ISO 2006
---------------------- Page: 3 ----------------------
SIST ISO 2846-1:2008
ISO 2846-1:2006(E)
PDF disclaimer
This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but
shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In
downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat
accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.
Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation
parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In
the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.
© ISO 2006
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2006 – All rights reserved
---------------------- Page: 4 ----------------------
SIST ISO 2846-1:2008
ISO 2846-1:2006(E)
Contents Page
Foreword. iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 2
4 Test method. 2
4.1 Procedure . 2
4.2 Test print preparation. 2
4.3 Colour measurement procedures . 3
5 Requirements for colour, transparency and ink film thickness range. 4
5.1 General. 4
5.2 Colorimetric values. 4
5.3 Transparency characteristics. 4
5.4 Ink film thickness. 4
Annex A (normative) Reference substrate . 5
Annex B (informative) Extended explanation of the test procedures, including examples . 6
Annex C (informative) Spectral data. 10
Annex D (informative) Tristimulus values for 8°:di geometry and illuminant D65 . 13
Bibliography . 15
© ISO 2006 – All rights reserved iii
---------------------- Page: 5 ----------------------
SIST ISO 2846-1:2008
ISO 2846-1:2006(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 2846-1 was prepared by Technical Committee ISO/TC 130, Graphic technology.
This second edition cancels and replaces the first edition (ISO 2846-1:1997), of which subclauses 4.2 and 5.2
and Annex D have been technically revised. Some very minor changes have been made for the purposes of
simplification, and an effort has been made to clarify and update this document in some places. Clauses 4
and 5 have been interchanged with each other. In addition, the test-print preparation requirements have been
deleted and referenced to ISO 2834-1. Annex B, describing the history of the development of the colour
standard, has been removed and Annex E relettered to Annex B.
ISO 2846 consists of the following parts, under the general title Graphic technology — Colour and
transparency of printing ink sets for four-colour printing:
⎯ Part 1: Sheet-fed and heat-set web offset lithographic printing
⎯ Part 2: Coldset offset lithographic printing
⎯ Part 3: Publication gravure printing
⎯ Part 4: Screen printing
⎯ Part 5: Flexographic printing
iv © ISO 2006 – All rights reserved
---------------------- Page: 6 ----------------------
SIST ISO 2846-1:2008
ISO 2846-1:2006(E)
Introduction
This part of ISO 2846 defines the colour and transparency of lithographic printing inks. Different sets of inks
(both for proof and production printing) conforming to this part of ISO 2846 will produce a similar colour when
printed on the same substrate at the appropriate film thickness. This enables colour separations for offset-
lithographic printing to be based on known colour references and simplifies the task of consistently printing the
same images in multiple printing sites.
It should be noted that the colorimetric characteristics specified can only be obtained when the inks are
printed on the reference substrate. However, the similarity of two inks on a reference substrate generally
ensures similarity on another substrate, and it is this similarity that has enabled industry specifications or
[1]
standards such as ISO 12647-2 , which specifies the colour of these inks on other substrates, to be
developed.
The colour specified in the previous edition of this part of ISO 2846 was based on extensive measurements of
commercial ink sets made in Europe, Japan and the USA. A working group of ISO/TC 130 process control
and material experts examined data sets from various countries at the time that edition was prepared and
found that a single set of colour coordinates could adequately represent all three proposals within reasonable
tolerances. In addition, they found that the transparency of various inks could also be adequately represented
by a new method of evaluation. A review undertaken prior to the revision of this edition suggested that there
had been little change in the colour and transparency of the inks commercially available and that the
characteristics specified in this part of ISO 2846 could be reconfirmed.
© ISO 2006 – All rights reserved v
---------------------- Page: 7 ----------------------
SIST ISO 2846-1:2008
---------------------- Page: 8 ----------------------
SIST ISO 2846-1:2008
INTERNATIONAL STANDARD ISO 2846-1:2006(E)
Graphic technology — Colour and transparency of printing ink
sets for four-colour printing —
Part 1:
Sheet-fed and heat-set web offset lithographic printing
1 Scope
This part of ISO 2846 specifies the colour and transparency characteristics that have to be met by each ink in
a process colour ink set intended for proof and production printing using offset lithography. The specified
printing conditions (which use a laboratory printability tester), the defined substrate and a method for testing to
ensure conformance are also defined. Characteristics are specified for inks used for sheet-fed, heat-set web
and radiation-curing processes.
This part of ISO 2846 does not apply to fluorescent inks and it does not specify pigments (or spectral
characteristics — except informatively) in order not to preclude developments which may enable different
pigment combinations to be used advantageously while still achieving the colorimetric requirements specified
in this part of ISO 2846.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 535, Paper and board — Determination of water absorptiveness — Cobb method
ISO 536, Paper and board — Determination of grammage
ISO 2144, Paper, board and pulps — Determination of residue (ash) on ignition at 900 °C
ISO 2834-1, Graphic technology — Laboratory preparation of test prints — Part 1: Paste inks
ISO 6588-1, Paper, board and pulps — Determination of pH of aqueous extracts — Part 1: Cold extraction
ISO 8254-1, Paper and board — Measurement of specular gloss — Part 1: 75° gloss with a converging beam,
TAPPI method
ISO 8791-4, Paper and board — Determination of roughness/smoothness (air leak methods) — Part 4: Print-
surf method
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic arts
images
ANSI CGATS.5:2003, Graphic technology — Spectral measurement and colorimetric computation for graphic
arts images
© ISO 2006 – All rights reserved 1
---------------------- Page: 9 ----------------------
SIST ISO 2846-1:2008
ISO 2846-1:2006(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
standard ink
ink intended for four-colour printing which, when printed on the reference substrate and within the applicable
range of ink film thicknesses, complies to the colorimetric and transparency specifications of this part of
ISO 2846
3.2
transparency
ability of an ink film to transmit light
NOTE It is generally expressed as some measure of the unwanted scattering.
3.3
transparency measurement value
T
reciprocal of the slope of the regression line between ink film thickness and colour difference for overprints of
chromatic inks over black substrate
4 Test method
4.1 Procedure
Colorimetric conformance shall be verified by printing each ink on the reference substrate, described in
Annex A, at a range of ink film thicknesses. The colours of the resultant test prints shall be measured and the
colour difference determined between the sample and the pertinent value given in Table 1. If at least one of
these samples has a smaller colour difference than that specified in 5.2, the ink conforms colorimetrically to
this part of ISO 2846.
NOTE It is often more convenient to determine the colorimetric conformance of an ink graphically. This is achieved
by calculating the colour difference (∆E* ) from the values in Table 1 for each of the prints made and plotting this against
ab
the ink film thickness. The ink conforms if the resultant curve shows a pronounced minimum which is below the ∆E* value
ab
specified in Table 1. (See Annex B for further information.)
Transparency value, T, shall be determined by printing each of the chromatic process inks on to a black
substrate meeting the requirements of 4.2.2, at a range of ink film thicknesses. The colour difference, ∆E* , is
ab
determined for each sample between the overprinted and unprinted black substrate. The gradient of the linear
regression of ink film thickness on colour difference shall be determined. An ink conforms to the transparency
requirements of this part of ISO 2846 if the reciprocal of the gradient is negative, or greater than the value
specified. (See Annex B for further information.)
The gradient of the regression equation may be determined directly from the data obtained. However, it is
recommended that it be obtained from a graphical plot of the values of ∆E* against ink film thickness. Such a
ab
plot enables any unexpected characteristics of the data to be easily visualised. (See Annex B for further
information.)
If one or more printed samples of each ink conform to the colorimetric values within the tolerances specified,
and the ink also meets the transparency criteria, that ink can be said to comply to this part of ISO 2846.
4.2 Test print preparation
4.2.1 Prints for colorimetric evaluation
For each of the inks to be evaluated, a number of test prints shall be made, each produced at a different ink
film thickness, according to the conditions specified in ISO 2834-1.
2 © ISO 2006 – All rights reserved
---------------------- Page: 10 ----------------------
SIST ISO 2846-1:2008
ISO 2846-1:2006(E)
They shall be made on the reference substrate specified in Annex A. The range of ink film thicknesses
produced shall encompass that specified for the process for which the ink is intended. (See 5.4.)
4.2.2 Prints for transparency evaluation
The test prints for transparency evaluation shall be produced by printing the inks to be tested on a black
substrate such that a minimum of four samples is achieved, each with a different ink film thickness. The
printing shall be undertaken as described in ISO 2834-1. The range of ink film thicknesses achieved should at
least cover that defined in 5.4.
The black substrate shall have a lightness, L*, less than 6 when determined in accordance with ISO 13655
(with the exception that a white backing shall be used when measuring the print; see 4.3).
Although in principle it is possible for the user to produce, themselves, the black substrate by printing, it is
difficult to ensure that the lightness is sufficiently low without adversely affecting the gloss and printing
properties of the substrate. It is usually preferable to use a black substrate or a substrate pre-printed
commercially. However, if it is necessary to print the black, the recommendations given in Annex B should be
1)
followed. Appropriate substrates are the contrast card or the contrast strip .
4.2.3 Drying of test prints
Prior to colour measurement, all samples shall be thoroughly dry. Inks formulated for oxidation drying shall be
left for at least 24 h, those formulated for radiation curing shall be dried with an appropriate radiation source
within the appropriate time and heat-set inks shall be heat dried with appropriate drying equipment.
NOTE Be aware that the appropriate time for radiation curing inks can be down to parts of a second only.
4.3 Colour measurement procedures
Test prints shall be measured in accordance with ISO 13655, except that a white backing which is in
conformance with ANSI CGATS.5 shall be used.
Conforming to ISO 13655 means that samples shall be measured spectrally, with a 0°:45°a or 45°a:0°
geometry instrument, and for calculation of CIELAB colour values the CIE 1931 (2°) standard colorimetric
observer data is used together with CIE standard illuminant D50; see Reference [3]. Where spectral data is
obtained at wavelength intervals greater than 5 nm, the weighting functions for the standard colorimetric
observer specified in ISO 13655 are used.
For calculating the colour difference from the reference values, the CIE 1976 colour difference, ∆E* , shall be
ab
used.
NOTE 1 ISO 13655 is currently under revision and it is the intent of the committee to add a white backing condition
identical to that of ANSI CGATS.5.
NOTE 2 For the comparison of measurements, it is useful to record the following details:
⎯ the ink designation and batch number;
⎯ the ink layer thicknesses;
⎯ the substrate used;
⎯ the printability tester used and the settings used on the tester (speed, force, printing forme);
⎯ environmental conditions (lab temperature and relative humidity);
⎯ spectrophotometer used;
⎯ any deviations from this part of ISO 2846.
1) Leneta paper or card (No. 105 C) which may be purchased from Leneta Corp., Mahwah, NJ, USA; contrast strip:
comparison test strips Ka APCO C with contrast band (several widths) which may be purchased from IGT Testing
Systems, Amsterdam, The Netherlands. These products are examples of suitable products available commercially. This
information is given for the convenience of users of this part of ISO 2846 and does not constitute an endorsement by ISO
of these products.
© ISO 2006 – All rights reserved 3
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SIST ISO 2846-1:2008
ISO 2846-1:2006(E)
5 Requirements for colour, transparency and ink film thickness range
5.1 General
For an ink to conform to this part of ISO 2846 it shall meet the specifications for colour defined in 5.2, and the
specification for transparency defined in 5.3, at some ink film thickness within the range specified in 5.4.
5.2 Colorimetric values
When printed in accordance with Clause 4, an ink shall produce a colour that falls within the defined colour
difference tolerances, ∆E* , from the L*, a*, b* values specified in Table 1.
ab
Table 1 — Colorimetric values for 0°:45°a geometry, illuminant D50, 2° observer
a a
CIELAB values Tolerances
Ink
L* a* b* ∆E* ∆a* ∆b* L*
ab
Yellow 91,0 −5,1 95,0 4,0 — — —
Magenta 50,0 76,0 4,0 — — —
−3,0
Cyan 57,0 −39,2 −46,0 4,0 — — —
b
Black 18,0 0,8 0,
...
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