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 2006
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ii © ISO 2006 – All rights reserved

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

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

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.
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
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

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
...