ISO/TR 12705:2011
(Main)Graphic technology — Laboratory test method for chemical ghosting in lithography
Graphic technology — Laboratory test method for chemical ghosting in lithography
ISO/TR 12705:2011 describes a laboratory method, using a printability tester, for the preparation of specimens in order to evaluate the tendency of a particular ink, substrate and printing procedure to produce chemical ghosting in sheet-fed offset lithography on coated papers or foils. A test procedure to induce ghosting using these specimens is also included. This method applies only to oxidative drying inks on coated papers or foils and it evaluates a particular ink and substrate combination.
Technologie graphique — Méthode d'essai en laboratoire pour impression fantôme chimique en lithographie
General Information
Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 12705
First edition
2011-10-15
Graphic technology — Laboratory test
method for chemical ghosting in
lithography
Technologie graphique — Méthode d'essai en laboratoire pour
impression fantôme chimique en lithographie
Reference number
ISO/TR 12705:2011(E)
©
ISO 2011
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ISO/TR 12705:2011(E)
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ii © ISO 2011 – All rights reserved
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ISO/TR 12705:2011(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.
In exceptional circumstances, when a technical committee has collected data of a different kind from that
which is normally published as an International Standard (“state of the art”, for example), it may decide by a
simple majority vote of its participating members to publish a Technical Report. A Technical Report is entirely
informative in nature and does not have to be reviewed until the data it provides are considered to be no
longer valid or useful.
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/TR 12705 was prepared by Technical Committee ISO/TC 130, Graphic technology.
© ISO 2011 – All rights reserved iii
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ISO/TR 12705:2011(E)
Introduction
This Technical Report describes a test method to evaluate the susceptibility of a particular ink, substrate and
printing procedure to produce chemical ghosting in sheet-fed offset lithographic printing. Chemical ghosting
occurs only in sheet-fed offset lithographic printing and appears mostly in dark areas of a print. A related
phenomenon, mechanical ghosting, can appear in both sheet-fed and web offset. This is due to the ink supply
limitations of some inking unit designs for sheet-fed offset presses; its origin is unknown in web-offset presses.
Chemical ghosting occurs during storage of freshly printed sheets in the output stack. Inks formulated from
natural fatty acids liberate volatile chemicals during oxidative drying. These might cause either
image-wise yellowing of the back side of the adjacent sheet in the stack (in either single side or perfecting
printing), or
variation in the drying speed of ink layers that are subsequently over-printed, which results in an image-
wise variation in gloss.
In both cases “ghost image artefacts” might be visible. Complete suppression of these artefacts can be
achieved by strictly separating the sheets. The effect of chemical ghosting depends on the nature and film
thickness of the printing inks, the substrate, climatic conditions, the time intervals between face and reverse
printing, and printing and converting.
The severity of chemical ghosting that manifests itself by differences in gloss may be reduced by:
a) measures that result in faster ink drying;
b) lower ink film thicknesses;
c) moderate temperatures;
d) medium relative humidity;
e) very short or very long intervals between face and reverse printing;
[3]
f) short converting intervals .
If prints are surface-finished by dispersion, UV lacquers, and sometimes oil lacquers, this tends to achieve a
[3]
homogeneous gloss level and therefore to suppress chemical ghosting .
Optical measurements like densitometry, colorimetry and gloss measurement at constant and variable angles
of illumination and detection have proven unsatisfactory in the evaluation of the severity of image-wise gloss
artefacts. These effects are better evaluated visually.
The reliability of the test method described in this Technical Report was validated by printing trials on a sheet-
[3][4]
fed offset printing press .
iv © ISO 2011 – All rights reserved
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TECHNICAL REPORT ISO/TR 12705:2011(E)
Graphic technology — Laboratory test method for chemical
ghosting in lithography
1 Scope
This Technical Report describes a laboratory method, using a printability tester, for the preparation of
specimens in order to evaluate the tendency of a particular ink, substrate and printing procedure to produce
chemical ghosting in sheet-fed offset lithography on coated papers or foils.
A test procedure to induce ghosting using these specimens is also included.
The presence of chemical ghosting is determined by visual evaluation of test images. Chemical ghosting can
appear either as reverse-side yellowing on single-side and perfect printing, or as image-wise gloss variations
in perfect printing. This method applies only to oxidative drying inks on coated papers or foils and it evaluates
a particular ink and substrate combination.
2 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
2.1
chemical ghosting
reverse-side and image-wise yellowing and/or gloss variations in face and reverse printing, typically in the
form of a mirror image
2.2
face and reverse printing
perfect printing
printing on both sides of a print substrate, either in the same run or in two subsequent runs
3 Test method
3.1 Principle
Two test prints are prepared, according to the procedures defined in ISO 2834-1, using the ink and substrate
combination to be evaluated. One of the test prints should have a large area o
...
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