SIST ISO 2846-1:2002
(Main)Graphic technology -- Colour and transparency of ink sets for four-colour-printing -- Part 1: Sheet-fed and heat-set web offset lithographic printing
Graphic technology -- Colour and transparency of 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
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
First edition
1997-12-15
Graphic technology — Colour and
transparency of 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
A
Reference number
ISO 2846-1:1997(E)
---------------------- Page: 1 ----------------------
ISO 2846-1:1997(E)
Contents
Page
1 Scope 1
2 Normative references 1
3 Definitions 2
4 Test method 2
5 Requirements for colour, transparency and ink film thickness ranges 5
Annexes
A Reference substrate 7
B Original ISO 2846:1975 specification and the reasons for change 9
C Spectral data 11
D Tristimulus values for 8°/diffuse geometry and illuminant D 14
65
E Extended explanation of the test procedures, including examples 16
© ISO 1997
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 the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet central@iso.ch
X.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii
---------------------- Page: 2 ----------------------
©
ISO ISO 2846-1:1997(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.
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.
International Standard ISO 2846-1 was prepared by Technical Committee ISO/TC 130, Graphic
technology.
It cancels and replaces ISO 2846:1975 and ISO 2845:1975, of which it constitutes a technical
revision.
ISO 2846 consists of the following parts, under the general title Graphic technology — Colour
and transparency of ink sets for four-colour-printing:
— Part 1: Sheet-fed and heat-set web offset lithographic printing
— Part 2: Newspaper printing
Annex A forms an integral part of this part of ISO 2846. Annexes B to E are for information
only.
iii
---------------------- Page: 3 ----------------------
©
ISO 2846-1:1997(E) ISO
Introduction
The original version of this part of ISO 2846 (ISO 2846:1975) was produced to allow
lithographic printers to obtain different sets of inks (both for proof and production printing)
which would produce a similar colour when printed on the same substrate at the appropriate film
thickness. By doing this, it enabled colour separations for offset-lithographic printing to be
based on known colour standards. It was accepted that the colorimetric characteristics specified
would only be obtained when the inks were printed on the reference substrate. However, it was
noted that similarity of two inks on a reference substrate would ensure similarity on another
substrate, as described above, and thereby enable industry specifications or standards for all
substrates to be developed when based on these inks. As time has passed, such specifications
have become increasingly important, so the significance of this part of ISO 2846 has increased
since its development.
The original specification was based on extensive measurements of commercial ink sets made in
Europe during the 1960s. However, by the end of the 1980s it was clear that some changes in the
colour of commercial inks had occurred and therefore the need for a revision of ISO 2846:1975
was required. This revision is based on input from the European Confederation of Paint, Printing
Ink and Artists' Colour Manufacturers' Associations (CEPE) who measured a number of
European commercial ink sets in recommending that a new standard (CIE 30-89) be prepared;
colorimetric data of commercial process inks of seven German manufacturers collected by
FOGRA; the National Association of Printing Ink Manufacturers (NAPIM) in the USA who used
inks for SWOP (Specifications for Web Offset Publications) as the basis of their ink data set
and the Japan Printing Ink Makers' Association who also defined a set of standard colours based
on measurements of commercial ink sets, known as Japan Colour Ink SF-90. More details on this
are given in annex C.
A joint working group consisting of TC 130 process control and material experts examined the
three inputs and found that a single set of colour coordinates could adequately represent all three
proposals within reasonable tolerances. It was also agreed that other changes and extensions to
the original International Standard ISO 2846:1975 were appropriate, including the inclusion of
black ink, a new measure of transparency (and therefore no definition of secondaries), changes to
the colorimetric references and explicit inclusion of inks requiring drying methods other than
oxidation drying. (Inks for cold-set newspaper printing are considered in ISO 2846-2.)
In comparison with ISO 2846:1975 the following major changes were made for this revision:
- reduction of chroma for cyan and magenta;
- slight red hue shift for the yellow;
- slight green hue shift for the cyan;
- specification of the black ink;
iv
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©
ISO ISO 2846-1:1997(E)
- change of the normative colorimetric conditions to D illuminant (rather than
50
illuminant C), 2° observer, CIELAB for specification and tolerances (rather than xyY
and U*V*W*), and 0°/45° (or 45°/0°) geometry;
- addition, for information only, of spectral data, D colorimetric data equivalent to
65
those for D and specifications for 8°/diffuse (or diffuse/8°) measuring geometry
50
equivalent to those for 0°/45° (or 45°/0°);
- choice of the perfect reflecting diffuser as the white reference;
- explicit inclusion of inks for heat-set web offset and radiation curing;
- specification of minimum transparency;
- no specification of secondaries;
- more specific details on test print preparation together with exclusive specification of a
laboratory printability tester for test print preparation;
- specification of the reference substrate;
- upward extension of the ink film thickness range;
- no provisions for lightfastness and solvent resistance.
v
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INTERNATIONAL STANDARD ©
ISO ISO 2846-1:1997(E)
Graphic technology — Colour and transparency of 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 a set of colours which will be produced by a series of inks
intended for four-colour offset-lithography (both proof and production printing) when printed
under specified conditions, on a defined substrate, using a laboratory printability tester. It also
describes the method for testing to ensure conformance. Information is provided on inks 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 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 standards contain provisions which, through reference in this text, constitute
provisions of this part of ISO 2846. At the time of publication, the editions indicated were valid.
All standards are subject to revision, and parties to agreements based on this part of ISO 2846 are
encouraged to investigate the possibility of applying the most recent editions of the standards
indicated below. Members of IEC and ISO maintain registers of currently valid International
Standards.
ISO 535:1991, .
Paper and board - Determination of water absorptiveness - Cobb method
ISO 536:1976, .
Paper and board - Determination of grammage
ISO 2144:1997, Paper, board and pulps - Determination of residue (ash) on ignition at 900 °C.
1)
ISO 2834:— , Graphic technology - Test print preparation for offset and letterpress inks.
1) To be published. (Revision of ISO 2834:1981)
1
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©
ISO 2846-1:1997(E) ISO
ISO 6588:1981, Paper, board and pulps - Determination of pH of aqueous extracts.
ISO/DIS 8254-1, Paper and board - Measurement of specular gloss - Part 1: 75° gloss.
ISO 8791-4:1992, Paper and board - Determination of roughness/smoothness (air leak methods)
- Part 4: Print-surf method.
ISO 13655:1996, Graphic technology - Spectral measurement and colorimetric computation for
graphic arts images.
ISO/CIE 10526: 1991, CIE standard colorimetric illuminants.
ISO/CIE 10527: 1991, CIE standard colorimetric observers.
CIE Publication 15.2: 1986, Colorimetry.
3 Definitions
For the purposes of this part of ISO 2846, the following 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 standard ink set: Complete set of standard inks comprising yellow, magenta, cyan and
black.
3.3 primary colours: Colours of individual prints from yellow, magenta and cyan inks. If the
prints are produced as specified in this part of ISO 2846 and conform to the colorimetric
characteristics specified, they are standard primary colours.
3.4 secondary colours: Colours obtained by overprinting pairs of the three chromatic inks.
3.5 transparency: Ability of an ink film to transmit and absorb light without scattering. It is
generally expressed as some measure of the unwanted scattering.
3.6 transparency measurement values: The reciprocal of the slope of the regression line
between ink film thickness and colour difference for overprints of chromatic inks over black.
4 Test method
4.1 Principle
Each ink to be tested shall be printed on the reference substrate (as described in annex A) at a
range of ink film thicknesses. The colours which result shall be measured colorimetrically. If
one or more samples are found which conform to the values and tolerances specified in this part
of ISO 2846, and the ink also meets the transparency criteria, that ink shall be deemed to be in
compliance with this part of ISO 2846.
2
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©
ISO ISO 2846-1:1997(E)
Transparency shall be evaluated by printing each of the three primary inks over black at a range
of film thicknesses. The CIELAB colour difference shall be determined for each sample,
between the printed and unprinted black, and the linear regression coefficient (slope of the
regression line) between ink film thickness and colour difference shall be calculated for each
colour. Inks conform to this part of ISO 2846 if the reciprocal of the coefficient is negative or
greater than the value specified in this part of ISO 2846. (A more detailed description of these
procedures, together with examples, is given in annex E.)
4.2 Test print preparation
4.2.1 Preparing 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 below.
They shall be made on the reference substrate as 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 5.3.)
- The prints shall be made using a printability tester.
- Printing shall be directly from the forme to the substrate.
- The ambient temperature shall be (24 ± 1)°C.
- Prints shall be produced with a printing line pressure of (225 ± 25) N/cm at a speed
of (1 ± 0,1) m/s.
- The printing forme, which shall be an elastomer or rubber blanket-covered roller,
shall have a Shore A hardness of between 80 and 85.
- The distribution time and the inking time for volatile (heat-set) inks shall not be
greater than 20 s each. This does not include weighing time. (See also 4.2.4.)
- The inking unit and the printing forme shall be cleaned and re-inked after each print.
NOTE - Solvent used to clean the forme may penetrate the material. Time shall
be allowed to ensure full evaporation of the solvent. Using two formes
alternately is recommended.
- The amount of ink transferred to the substrate shall be determined by measuring the
difference in mass of the printing forme before and after printing and shall be
expressed as g/m². Conversion to film thickness in micrometres shall be made by
using the mass density of the ink and the area of the print.
- Separate distribution rollers and printing formes with suitable material properties
shall be used for radiation-cured inks.
NOTE - For further information see ISO 2834.
3
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©
ISO 2846-1:1997(E) ISO
4.2.2 Preparing prints for transparency evaluation
Test prints for transparency evaluation shall be produced by printing the inks to be tested over
black. The black shall have a lightness (L*) less than 6 when determined according to the
principles of ISO 13655 (with the exception that a white backing shall be used when measuring
the print) as described in 4.3.
Such a substrate may be obtained by purchasing pre-printed material such as Leneta paper or
2)
card (No. 105C) supplied by the Leneta Corporation or may be produced by printing the
reference substrate, or a coated substrate of similar opacity, with one or more applications of
black ink. A black shall be selected which exhibits minimal bronzing and provides a gloss which
will not change significantly when overprinted by the test ink.
Sufficient time shall be allowed for the black ink to dry prior to the printing needed to test the
transparency of the coloured inks.
Since the CIELAB values of the black print need to be established, both when unprinted and
overprinted by the chromatic ink, the measurements of the black alone shall be made prior to
overprinting.
The ink to be tested shall then be printed as described in ISO 2834, on the prepared substrate,
such that a range of samples, each with a different ink film thickness, is achieved. The range
should cover that defined in 5.3, namely 0,7 μm to 1,3 μm.
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 24 h; those formulated for radiation curing shall be dried with an
appropriate radiation source and heat-set inks shall be heat dried with appropriate drying
equipment.
4.2.4 Additional considerations for heat-set inks
If problems in ink transfer arise, due to evaporation of volatile mineral oils in heat-set inks, a
small amount of oil (e.g. linseed oil) may be added to the ink prior to ink distribution. The
amount of oil added shall be kept as low as possible and shall not exceed 5 %. The amount of oil
added (by volume) shall be noted and used to correct the ink film thickness prior to assessment
of the ink against this part of ISO 2846.
4.3 Colour measurement procedures
Test prints shall be measured in accordance with ISO 13655, except that a white backing
consisting of at least 3 sheets of the unprinted substrate shall be used. For details concerning the
colorimetric illuminants and observers see ISO/CIE 10526 and ISO/CIE 10527.
2) Leneta paper or card is the trade-name of a product supplied by the Leneta Corporation. This information is given for the convenience of
users of this part of ISO 2846 and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they
can be shown to lead to the same results.
4
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©
ISO ISO 2846-1:1997(E)
Following ISO 13655 means that samples shall be measured spectrally, with a 0°/45° or 45°/0°
geometry instrument, and for calculation of tristimulus values the CIE 1931 (2°) standard
colorimetric observer data shall be used together with CIE standard illuminant D . For
50
calculating the colour difference from the reference values, CIELAB shall be used. For details
concerning the CIELAB colour space see CIE Publication 15.2: 1986.
5 Requirements for colour, transparency and ink film thickness ranges
For an ink to conform to this part of ISO 2846 it shall meet the specifications for colour defined
in 5.1, at some ink film thickness within the range specified in 5.3, and the specification for
transparency defined in 5.2.
5.1 Colorimetric values
These are specified in two ways which are equivalent when calculated according to the
procedures of ISO 13655. To meet the specification for colour, an ink shall produce a colour that
falls within the defined colour difference tolerances from the L*, a*, b* values specified in
table 1, at some ink film thickness within the specified range when printed as described in
clause 4.
o o o
Table 1 — Colorimetric values for 0 /45 geometry, illuminant D , 2 observer
50
1)
Tristimulus values CIELAB values Tolerances
Ink
XY Z L* a* b* ΔE * Δa* Δb* L*
ab
Yellow 73,21 78,49 7,40 91,00 -5,08 94,97 4,0 — — —
Magenta 36,11 18,40 16,42 49,98 76,02 -3,01 5,0 — — —
Cyan 16,12 24,91 52,33 56,99 -39,16 -45,99 3,0 — — —
2)
Black 2,47 2,52 2,14 18,01 0,80 -0,56 — ± 1,5 ± 3,0 18,0
≤
1) This means that for black there is no symmetrical tolerance for L* but an upper limit.
2) Two decimal places serve for correct conversion of the colorimetric values.
NOTES
1 Typical spectral data for inks conforming to this part of ISO 2846 are provided in
informative annex C. Reference spectral data for 8°/diffuse or diffuse/8° (specular
included) geometry are also included in informative annex C.
2 Reference data for tristimulus values calculated from the CIE 1931 (2°) standard
colorimetric observer, together with CIE illuminant D , are included in informative
65
annex D for both geometries. Tristimulus data for 8°/diffuse or diffuse/8° (specular
included) geometry and illuminant D are also included in annex D.
50
5.2 Transparency characteristics
To meet the specification for transparency, an ink shall produce a value greater than that
specified in table 2 when determined by the procedures and principles outlined in clause 4.
5
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©
ISO 2846-1:1997(E) ISO
Table 2 - Transparency requirements
Transparency
Ink
measurement value T
Magenta 0,12
Yellow 0,08
Cyan 0,20
NOTES
1 For highly transparent inks (usually cyan) the slope of the regression line may be zero
or negative. In such a situation the transparency value is considered to be approaching
infinity and therefore, it meets the specification.
2 Transparency data for inks conforming to this part of ISO 2846, but measured with
8°/diffuse or diffuse/8° (specular excluded) geometry, cannot be provided in an
informative annex as has been done for colorimetric parameters. This is due to the higher
sensitivity of the results from instruments with such geometries to surface effects, such as
bronzing or gloss changes, as discussed in annex E. However, the procedure can prove
useful for ranking inks of similar gloss and so a brief description is also provided in
annex E.
5.3 Ink film thickness
The range of ink film thicknesses (in micrometres), within which a standard ink shall conform, is
provided in table 3 for the different ink drying processes specified in this part of ISO 2846.
Table 3 - Range of ink film thicknesses
Values in μm
Ink type Cyan Magenta Yellow Black
Drying by oxidation/setting 0,7-1,1 0,7-1,1 0,7-1,1 0,9-1,3
Radiation curing 0,7-1,3 0,7-1,3 0,7-1,3 0,9-1,3
Heat-set web 0,7-1,3 0,7-1,3 0,7-1,3 0,9-1,3
6
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©
ISO ISO 2846-1:1997(E)
Annex A
(normative)
Reference substrate
For the purposes of this part of ISO 2846, a lightfast gloss-coated wood-free paper free of optical
brightener shall be used, the characteristics of which shall be as follows:
Colorimetric values
Tristimulus values CIELAB values
X = 85,32 L* = 95,46 ± 2,0
Y = 88,71 a* = -0,40 ± 1,0
= 67,96 * = 4,70 ± 1,5
Z b
Method: ISO 13655:1996,
Graphic technology — Spectral measurement and
colorimetric computation for graphic arts images; clauses 4 and 5
(0°/45°, D , 2°, but white backing)
50
Water absorptiveness
Specification: 2 g/m² to 5 g/m² after 10 s
Method: ISO 535:1991, Paper and board - Determination of water
absorptiveness — Cobb method.
Gloss
Specification: 70 % to 80 %
Method: ISO/DIS 8254-1, Paper and board - Measurement of specular gloss —
Part 1: 75° gloss.
Mass per area
Specification: (150 ± 3) g/m²
Method: ISO 536:1976, Paper and board - Determination of grammage.
Ash content
Specification: 20 % to 30 %
Method: ISO 2144:1997, Paper, board and pulps - Determination of residue
(ash) on ignition at 900 °C.
pH
Specification: 8 - 10
Method: ISO 6588:1981, Paper, board and pulps - Determination of pH of
aqueous extracts.
7
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©
ISO 2846-1:1997(E) ISO
Roughness
Specification: 0,9 μm - 1,1 μm at a pressure of 1 N/mm²
Method: ISO 8791-4:1992, Paper and board - Determination of
roughness/smoothness (air leak methods) - Part 4: Print-surf method.
NOTE — In practice there has been only one supplier of this material and this has
become the de facto standard. This material is the gloss-coated wood-free paper Phoenix
3)
Imperial APCO II/II
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SLOVENSKI STANDARD
SIST ISO 2846-1:2002
01-november-2002
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EDUYGHO 2IVHWQLWLVNQDSROHLQRIVHWQLWLVNQDURWDFLMDK]YURþLPVXãHQMHP
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Graphic technology -- Colour and transparency of 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
Ta slovenski standard je istoveten z: ISO 2846-1:1997
ICS:
17.180.20 Barve in merjenje svetlobe Colours and measurement of
light
87.080 Barvila. Tiskarske barve Inks. Printing inks
SIST ISO 2846-1:2002 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 2846-1:2002
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SIST ISO 2846-1:2002
INTERNATIONAL ISO
STANDARD 2846-1
First edition
1997-12-15
Graphic technology — Colour and
transparency of 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
A
Reference number
ISO 2846-1:1997(E)
---------------------- Page: 3 ----------------------
SIST ISO 2846-1:2002
ISO 2846-1:1997(E)
Contents
Page
1 Scope 1
2 Normative references 1
3 Definitions 2
4 Test method 2
5 Requirements for colour, transparency and ink film thickness ranges 5
Annexes
A Reference substrate 7
B Original ISO 2846:1975 specification and the reasons for change 9
C Spectral data 11
D Tristimulus values for 8°/diffuse geometry and illuminant D 14
65
E Extended explanation of the test procedures, including examples 16
© ISO 1997
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 the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet central@iso.ch
X.400 c=ch; a=400net; p=iso; o=isocs; s=central
Printed in Switzerland
ii
---------------------- Page: 4 ----------------------
SIST ISO 2846-1:2002
©
ISO ISO 2846-1:1997(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.
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.
International Standard ISO 2846-1 was prepared by Technical Committee ISO/TC 130, Graphic
technology.
It cancels and replaces ISO 2846:1975 and ISO 2845:1975, of which it constitutes a technical
revision.
ISO 2846 consists of the following parts, under the general title Graphic technology — Colour
and transparency of ink sets for four-colour-printing:
— Part 1: Sheet-fed and heat-set web offset lithographic printing
— Part 2: Newspaper printing
Annex A forms an integral part of this part of ISO 2846. Annexes B to E are for information
only.
iii
---------------------- Page: 5 ----------------------
SIST ISO 2846-1:2002
©
ISO 2846-1:1997(E) ISO
Introduction
The original version of this part of ISO 2846 (ISO 2846:1975) was produced to allow
lithographic printers to obtain different sets of inks (both for proof and production printing)
which would produce a similar colour when printed on the same substrate at the appropriate film
thickness. By doing this, it enabled colour separations for offset-lithographic printing to be
based on known colour standards. It was accepted that the colorimetric characteristics specified
would only be obtained when the inks were printed on the reference substrate. However, it was
noted that similarity of two inks on a reference substrate would ensure similarity on another
substrate, as described above, and thereby enable industry specifications or standards for all
substrates to be developed when based on these inks. As time has passed, such specifications
have become increasingly important, so the significance of this part of ISO 2846 has increased
since its development.
The original specification was based on extensive measurements of commercial ink sets made in
Europe during the 1960s. However, by the end of the 1980s it was clear that some changes in the
colour of commercial inks had occurred and therefore the need for a revision of ISO 2846:1975
was required. This revision is based on input from the European Confederation of Paint, Printing
Ink and Artists' Colour Manufacturers' Associations (CEPE) who measured a number of
European commercial ink sets in recommending that a new standard (CIE 30-89) be prepared;
colorimetric data of commercial process inks of seven German manufacturers collected by
FOGRA; the National Association of Printing Ink Manufacturers (NAPIM) in the USA who used
inks for SWOP (Specifications for Web Offset Publications) as the basis of their ink data set
and the Japan Printing Ink Makers' Association who also defined a set of standard colours based
on measurements of commercial ink sets, known as Japan Colour Ink SF-90. More details on this
are given in annex C.
A joint working group consisting of TC 130 process control and material experts examined the
three inputs and found that a single set of colour coordinates could adequately represent all three
proposals within reasonable tolerances. It was also agreed that other changes and extensions to
the original International Standard ISO 2846:1975 were appropriate, including the inclusion of
black ink, a new measure of transparency (and therefore no definition of secondaries), changes to
the colorimetric references and explicit inclusion of inks requiring drying methods other than
oxidation drying. (Inks for cold-set newspaper printing are considered in ISO 2846-2.)
In comparison with ISO 2846:1975 the following major changes were made for this revision:
- reduction of chroma for cyan and magenta;
- slight red hue shift for the yellow;
- slight green hue shift for the cyan;
- specification of the black ink;
iv
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SIST ISO 2846-1:2002
©
ISO ISO 2846-1:1997(E)
- change of the normative colorimetric conditions to D illuminant (rather than
50
illuminant C), 2° observer, CIELAB for specification and tolerances (rather than xyY
and U*V*W*), and 0°/45° (or 45°/0°) geometry;
- addition, for information only, of spectral data, D colorimetric data equivalent to
65
those for D and specifications for 8°/diffuse (or diffuse/8°) measuring geometry
50
equivalent to those for 0°/45° (or 45°/0°);
- choice of the perfect reflecting diffuser as the white reference;
- explicit inclusion of inks for heat-set web offset and radiation curing;
- specification of minimum transparency;
- no specification of secondaries;
- more specific details on test print preparation together with exclusive specification of a
laboratory printability tester for test print preparation;
- specification of the reference substrate;
- upward extension of the ink film thickness range;
- no provisions for lightfastness and solvent resistance.
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SIST ISO 2846-1:2002
INTERNATIONAL STANDARD ©
ISO ISO 2846-1:1997(E)
Graphic technology — Colour and transparency of 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 a set of colours which will be produced by a series of inks
intended for four-colour offset-lithography (both proof and production printing) when printed
under specified conditions, on a defined substrate, using a laboratory printability tester. It also
describes the method for testing to ensure conformance. Information is provided on inks 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 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 standards contain provisions which, through reference in this text, constitute
provisions of this part of ISO 2846. At the time of publication, the editions indicated were valid.
All standards are subject to revision, and parties to agreements based on this part of ISO 2846 are
encouraged to investigate the possibility of applying the most recent editions of the standards
indicated below. Members of IEC and ISO maintain registers of currently valid International
Standards.
ISO 535:1991, .
Paper and board - Determination of water absorptiveness - Cobb method
ISO 536:1976, .
Paper and board - Determination of grammage
ISO 2144:1997, Paper, board and pulps - Determination of residue (ash) on ignition at 900 °C.
1)
ISO 2834:— , Graphic technology - Test print preparation for offset and letterpress inks.
1) To be published. (Revision of ISO 2834:1981)
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ISO 6588:1981, Paper, board and pulps - Determination of pH of aqueous extracts.
ISO/DIS 8254-1, Paper and board - Measurement of specular gloss - Part 1: 75° gloss.
ISO 8791-4:1992, Paper and board - Determination of roughness/smoothness (air leak methods)
- Part 4: Print-surf method.
ISO 13655:1996, Graphic technology - Spectral measurement and colorimetric computation for
graphic arts images.
ISO/CIE 10526: 1991, CIE standard colorimetric illuminants.
ISO/CIE 10527: 1991, CIE standard colorimetric observers.
CIE Publication 15.2: 1986, Colorimetry.
3 Definitions
For the purposes of this part of ISO 2846, the following 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 standard ink set: Complete set of standard inks comprising yellow, magenta, cyan and
black.
3.3 primary colours: Colours of individual prints from yellow, magenta and cyan inks. If the
prints are produced as specified in this part of ISO 2846 and conform to the colorimetric
characteristics specified, they are standard primary colours.
3.4 secondary colours: Colours obtained by overprinting pairs of the three chromatic inks.
3.5 transparency: Ability of an ink film to transmit and absorb light without scattering. It is
generally expressed as some measure of the unwanted scattering.
3.6 transparency measurement values: The reciprocal of the slope of the regression line
between ink film thickness and colour difference for overprints of chromatic inks over black.
4 Test method
4.1 Principle
Each ink to be tested shall be printed on the reference substrate (as described in annex A) at a
range of ink film thicknesses. The colours which result shall be measured colorimetrically. If
one or more samples are found which conform to the values and tolerances specified in this part
of ISO 2846, and the ink also meets the transparency criteria, that ink shall be deemed to be in
compliance with this part of ISO 2846.
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Transparency shall be evaluated by printing each of the three primary inks over black at a range
of film thicknesses. The CIELAB colour difference shall be determined for each sample,
between the printed and unprinted black, and the linear regression coefficient (slope of the
regression line) between ink film thickness and colour difference shall be calculated for each
colour. Inks conform to this part of ISO 2846 if the reciprocal of the coefficient is negative or
greater than the value specified in this part of ISO 2846. (A more detailed description of these
procedures, together with examples, is given in annex E.)
4.2 Test print preparation
4.2.1 Preparing 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 below.
They shall be made on the reference substrate as 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 5.3.)
- The prints shall be made using a printability tester.
- Printing shall be directly from the forme to the substrate.
- The ambient temperature shall be (24 ± 1)°C.
- Prints shall be produced with a printing line pressure of (225 ± 25) N/cm at a speed
of (1 ± 0,1) m/s.
- The printing forme, which shall be an elastomer or rubber blanket-covered roller,
shall have a Shore A hardness of between 80 and 85.
- The distribution time and the inking time for volatile (heat-set) inks shall not be
greater than 20 s each. This does not include weighing time. (See also 4.2.4.)
- The inking unit and the printing forme shall be cleaned and re-inked after each print.
NOTE - Solvent used to clean the forme may penetrate the material. Time shall
be allowed to ensure full evaporation of the solvent. Using two formes
alternately is recommended.
- The amount of ink transferred to the substrate shall be determined by measuring the
difference in mass of the printing forme before and after printing and shall be
expressed as g/m². Conversion to film thickness in micrometres shall be made by
using the mass density of the ink and the area of the print.
- Separate distribution rollers and printing formes with suitable material properties
shall be used for radiation-cured inks.
NOTE - For further information see ISO 2834.
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4.2.2 Preparing prints for transparency evaluation
Test prints for transparency evaluation shall be produced by printing the inks to be tested over
black. The black shall have a lightness (L*) less than 6 when determined according to the
principles of ISO 13655 (with the exception that a white backing shall be used when measuring
the print) as described in 4.3.
Such a substrate may be obtained by purchasing pre-printed material such as Leneta paper or
2)
card (No. 105C) supplied by the Leneta Corporation or may be produced by printing the
reference substrate, or a coated substrate of similar opacity, with one or more applications of
black ink. A black shall be selected which exhibits minimal bronzing and provides a gloss which
will not change significantly when overprinted by the test ink.
Sufficient time shall be allowed for the black ink to dry prior to the printing needed to test the
transparency of the coloured inks.
Since the CIELAB values of the black print need to be established, both when unprinted and
overprinted by the chromatic ink, the measurements of the black alone shall be made prior to
overprinting.
The ink to be tested shall then be printed as described in ISO 2834, on the prepared substrate,
such that a range of samples, each with a different ink film thickness, is achieved. The range
should cover that defined in 5.3, namely 0,7 μm to 1,3 μm.
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 24 h; those formulated for radiation curing shall be dried with an
appropriate radiation source and heat-set inks shall be heat dried with appropriate drying
equipment.
4.2.4 Additional considerations for heat-set inks
If problems in ink transfer arise, due to evaporation of volatile mineral oils in heat-set inks, a
small amount of oil (e.g. linseed oil) may be added to the ink prior to ink distribution. The
amount of oil added shall be kept as low as possible and shall not exceed 5 %. The amount of oil
added (by volume) shall be noted and used to correct the ink film thickness prior to assessment
of the ink against this part of ISO 2846.
4.3 Colour measurement procedures
Test prints shall be measured in accordance with ISO 13655, except that a white backing
consisting of at least 3 sheets of the unprinted substrate shall be used. For details concerning the
colorimetric illuminants and observers see ISO/CIE 10526 and ISO/CIE 10527.
2) Leneta paper or card is the trade-name of a product supplied by the Leneta Corporation. This information is given for the convenience of
users of this part of ISO 2846 and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they
can be shown to lead to the same results.
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Following ISO 13655 means that samples shall be measured spectrally, with a 0°/45° or 45°/0°
geometry instrument, and for calculation of tristimulus values the CIE 1931 (2°) standard
colorimetric observer data shall be used together with CIE standard illuminant D . For
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calculating the colour difference from the reference values, CIELAB shall be used. For details
concerning the CIELAB colour space see CIE Publication 15.2: 1986.
5 Requirements for colour, transparency and ink film thickness ranges
For an ink to conform to this part of ISO 2846 it shall meet the specifications for colour defined
in 5.1, at some ink film thickness within the range specified in 5.3, and the specification for
transparency defined in 5.2.
5.1 Colorimetric values
These are specified in two ways which are equivalent when calculated according to the
procedures of ISO 13655. To meet the specification for colour, an ink shall produce a colour that
falls within the defined colour difference tolerances from the L*, a*, b* values specified in
table 1, at some ink film thickness within the specified range when printed as described in
clause 4.
o o o
Table 1 — Colorimetric values for 0 /45 geometry, illuminant D , 2 observer
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1)
Tristimulus values CIELAB values Tolerances
Ink
XY Z L* a* b* ΔE * Δa* Δb* L*
ab
Yellow 73,21 78,49 7,40 91,00 -5,08 94,97 4,0 — — —
Magenta 36,11 18,40 16,42 49,98 76,02 -3,01 5,0 — — —
Cyan 16,12 24,91 52,33 56,99 -39,16 -45,99 3,0 — — —
2)
Black 2,47 2,52 2,14 18,01 0,80 -0,56 — ± 1,5 ± 3,0 18,0
≤
1) This means that for black there is no symmetrical tolerance for L* but an upper limit.
2) Two decimal places serve for correct conversion of the colorimetric values.
NOTES
1 Typical spectral data for inks conforming to this part of ISO 2846 are provided in
informative annex C. Reference spectral data for 8°/diffuse or diffuse/8° (specular
included) geometry are also included in informative annex C.
2 Reference data for tristimulus values calculated from the CIE 1931 (2°) standard
colorimetric observer, together with CIE illuminant D , are included in informative
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annex D for both geometries. Tristimulus data for 8°/diffuse or diffuse/8° (specular
included) geometry and illuminant D are also included in annex D.
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5.2 Transparency characteristics
To meet the specification for transparency, an ink shall produce a value greater than that
specified in table 2 when determined by the procedures and principles outlined in clause 4.
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Table 2 - Transparency requirements
Transparency
Ink
measurement value T
Magenta 0,12
Yellow 0,08
Cyan 0,20
NOTES
1 For highly transparent inks (usually cyan) the slope of the regression line may be zero
or negative. In such a situation the transparency value is considered to be approaching
infinity and therefore, it meets the specification.
2 Transparency data for inks conforming to this part of ISO 2846, but measured with
8°/diffuse or diffuse/8° (specular excluded) geometry, cannot be provided in an
informative annex as has been done for colorimetric parameters. This is due to the higher
sensitivity of the results from instruments with such geometries to surface effects, such as
bronzing or gloss changes, as discussed in annex E. However, the procedure can prove
useful for ranking inks of similar gloss and so a brief description is also provided in
annex E.
5.3 Ink film thickness
The range of ink film thicknesses (in micrometres), within which a standard ink shall conform, is
provided in table 3 for the different ink drying processes specified in this part of ISO 2846.
Table 3 - Range of ink film thicknesses
Values in μm
Ink type Cyan Magenta Yellow Black
Drying by oxidation/setting 0,7-1,1 0,7-1,1 0,7-1,1 0,9-1,3
Radiation curing 0,7-1,3 0,7-1,3 0,7-1,3 0,9-1,3
Heat-set web 0,7-1,3 0,7-1,3 0,7-1,3 0,9-1,3
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Annex A
(normative)
Reference substrate
For the purposes of this part of ISO 2846, a lightfast gloss-coated wood-free paper free of optical
brightener shall be used, the characteristics of which shall be as follows:
Colorimetric values
Tristimulus values CIELAB values
X = 85,32 L* = 95,46 ± 2,0
Y = 88,71 a* = -0,40 ± 1,0
= 67,96 * = 4,70 ± 1,5
Z b
Method: ISO 13655:1996,
Graphic technology — Spectral measurement and
colorimetric computation for graphic arts images; clauses 4 and 5
(0°/45°, D , 2°, but white backing)
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Water absorptiveness
Specification: 2 g/m² to 5 g/m² after 10 s
Method: ISO 535:1991, Paper and board - Determination of water
absorptiveness — Cobb method.
Gloss
Specification: 70 % to 80 %
Method: ISO/DIS 8254-1, Paper and board - Measurement of specular gloss —
Part 1: 75° gloss.
Mass per area
Specification: (150 ± 3) g/m²
Method: ISO 536:1976, Paper and board - Determination of grammage.
Ash content
Specification: 20 % to 30 %
Method: ISO 2144:1997, Paper, board and pulps - Determination of residue
(ash) on ignition at 900 °C.
pH
Specification: 8 - 10
Method: ISO 6588:1981, Paper, board and pulps - Determination of pH of
aqueous extracts.
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Roughness
Specification: 0,9 μm - 1,1 μm at a pressure of 1 N/mm²
Method: ISO 8791-4:1992, Paper and board - Determination of
roughness/smoothness (air leak methods) - Part 4: Print-surf method.
NOTE — In practice there has been only one supplier of this material and this has
become the de facto standard. This material is the gloss-coated wood-free paper Phoenix
3)
Imperial APCO II/II from Scheufelen, D-73250 Lenningen, Germany.
3) Phoenix Imperial APCO II/II is an example of a suitable product 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 this product.
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Annex B
(informative)
Original ISO 2846:1975 specification and the reasons for change
ISO 2846:1975 was based on work carried out by the European Confederation of Paint, Printing
Ink and Artists' Colour Manufacturers' Association (CEPE) to specify letterpress printing inks
(CIE document No. 12-66). This was later extended to offset printing inks (CIE document
No. 13-67). Ten European national standards institutions adopted the contents of CIE documents
12-66 and 13-67 as national standards. The ink set colours so defined became known as the
European Colour Scale; they were modelled around a set of readily available pigments which
combined sufficient fastness values with favourable coloristic properties. Subsequently,
ISO 2845:1975 for letterpress and ISO 2846:1975 for offset printing inks were based on the
European Colour Scale.
Some 15 years later it had become apparent that, for many commercial inks, the chroma of cyan
and, to a lesser extent, magenta had decreased and yellow had shifted slightly in hue towards the
red and to a higher chroma. In response, a new standard proposal was published by CEPE in
1989 as CIE document No. 30-89. The three new specifications in that document individually
addressed sheet-fed, heat-set web and newspaper offset printing. The first two of these served as
input to this part of ISO 2846.
In the United States, the "Specifications for Web Offset Publications", later also known as
SWOP , were first proposed in 1975. They encompassed printed ink on paper standards (which
were defined densitometrically) and a well-defined printing ink for proofing on sheet-fed presses.
In 1986, the specifications were extended to production printing. Later, a colorimetric definition
of SWOP ink set colours was worked out in cooperation with NAPIM, the National
Association of Printing Ink Manufacturers in the US. This served as the second input to this part
of ISO 2846.
The Japanese Printers Association and the Japan Printing Ink Makers' Association jointly
established a set of standard process colours in 1964. However, it was not adopted as a national
standard at that time. In 1990, a task force of the Japan Printing Ink Makers' Association
established a set of standard colours named "Japan Colour Ink SF-90" which were based on
typical, commercially available ink sets from the eight major ink manufacturers in Japan. This
served as the third input to this part of ISO 2846.
In Germany, a colorimetric evaluation of typical, commercially available ink sets from the major
seven ink manufacturers undertaken by FOGRA in 1992 showed that cyan is greener, and yellow
less chromatic, than proposed in CIE 30-89. The average values from this served as the fourth
input to this part of ISO 2846.
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Old ISO 2846:1975 specification
For comparative purposes the values of the original ISO 2846:1975 specification are shown in
table B.1. They have been recalculated to facilitate the comparison, as shown in the notes.
Table B.1 - Original ISO 2846:1975 Colorimetric specification
Ink Tristimulus values Tolerances
XY Z ΔE
CIE
Yellow 72,40 77,79 8,24 2,3
Magenta 36,46 18,13 14,86 5,0
Cyan 13,40 20,22 49,59 3,0
Yellow + Magenta 34,60 17,57 2,40 7,3
Yellow + Cyan 5,91 15,99 6,65 5,3
Magenta + Cyan 3,87 2,53 13,23 8,0
NOTES
1 The values specified in ISO 2846:1975 were derived for the 2° observer and
illuminant C using magnesium oxide as the reference white. The above values have
been recalculated for the perfect diffuser and illuminant D , to enable a better
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comparison with the new values of this part of ISO 2846.
2 The tolerances are expressed in the 1964 CIE-UCS system (U*,V*,W*).
3 The reference substrate was not specified in ISO 2846:1975 but reference was made
to ISO 2834:1981, Printing Inks - Preparation of standardized prints for
determination of resistance to physical and chemical agents.
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Annex C
(informative)
Spectral data
For some applications, such as calculating tristimulus values for a different observer or
illuminant, it is useful to have recourse to spectral data. As already stated, it was deliberately
decided not to standardize such data since it can be very restrictive for ink manufacturing and the
future development of ink with improved properties. However, the following data may be taken
as 'typical' of that which was obtained when the European, Japanese and American inks were
averaged. Since most inks are currently based on the same pigments, any differences at the
present time are likely to be small. It must be stressed that this definition is informative and is
not a normative entity of this part of ISO 2846; inks cannot be assumed to be close to this data
for standardization purposes. It must also be remembered that these values are derived from
measurements made on samples printed on the reference substrate backed by white.
Two tables of data are presented: Table C.1 is for 0°/45° geometry and table C.2 is for 8°/diffuse
(specular included). This data has been used to compute equivalent tristimulus values to those
provided in 5.1 for 8°/diffuse geometry and for D (both geometries). These tristimulus values
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are given in annex D.
NOTE — For the purposes of this part of ISO 2846, the 0°/45° and 45°/0° geometries are
deemed to be equivalent to each other as are the 8°/diffuse and diffuse/8° geometries for
both specular-included and specular-excluded conditions. Thus, whilst only one of the
equivalent geometries is specified in the tables of this annex it may be interpreted that
either is acceptable. Of course, the values obtained with each geometry are different and
specular-included measurement results are different from those obtained with specular-
excluded measurements.
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