ISO/TS 19857:2021
(Main)Paper, board and printing inks – Printability – Laboratory test method for offset ink setting
Paper, board and printing inks – Printability – Laboratory test method for offset ink setting
This document describes a laboratory test method, using an IGT1-type or a prüfbau2-type printability tester, for the preparation of specimens to evaluate the absorption rate of an ink on a substrate in offset lithography by setting-off the printed surface to an unprinted surface. This method describes testing with an amount of ink simulating either single colour or multi-colour printing. The print and the set-off print (counter print) are made with interval times, between print and set-off, common for the target process. This method evaluates a particular ink and substrate combination. 1These materials are available from IGT Testing Systems, www.igt.nl. This information is given for the convenience of the users of this document and does not constitute an endorsement by ISO of the products. Equivalent products may be used if they can be shown to lead to the same results. 2These materials are available from prüfbau, Dr.-Ing. H. Dürner GmbH, www.pruefbau.de. This information is given for the convenience of the users of this document and does not constitute an endorsement by ISO of the products. Equivalent products may be used if they can be shown to lead to the same results.
Papier, carton et encres d'impression – Imprimabilité – Méthode d'essai de laboratoire pour le séchage de l'encre offset
General Information
Buy Standard
Standards Content (Sample)
TECHNICAL ISO/TS
SPECIFICATION 19857
First edition
2021-06
Paper, board and printing inks –
Printability – Laboratory test method
for offset ink setting
Papier, carton et encres d'impression – Imprimabilité – Méthode
d'essai de laboratoire pour le séchage de l'encre offset
Reference number
ISO/TS 19857:2021(E)
©
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TS 19857:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 19857:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Apparatus and materials. 2
4.1 Printing device . 2
4.2 Inking device . 3
4.3 Printing formes . 3
4.4 Ink pipette . 4
4.5 Packing . 4
4.6 Substrate carrier . 4
4.7 Analytical balance. 4
4.8 Timer . 4
4.9 Densitometer . 4
4.10 Test paper . 5
4.11 Reference counter test strips . 5
4.12 Setting test ink . 5
4.13 Cleaning . 5
5 Test method . 5
5.1 Principle . 5
5.2 Test conditions . 5
5.2.1 Climatic conditions . 5
5.2.2 Settings of the printability tester . 6
5.2.3 Settings for the inking unit . 6
6 Procedure. 7
6.1 Preparation . 7
6.2 Preparational test for ink transfer determination. 7
6.3 Test execution on different instruments . 7
6.3.1 IGT-type testers . 7
6.3.2 Prüfbau-type testers . 8
7 Assessment . 9
8 Reporting .10
Annex A (informative) Checking the printing device and the inking device .11
Annex B (informative) Visualization of defects of used materials.12
Bibliography .22
© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/TS 19857:2021(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee
SC 2, Test methods and quality specifications for paper and board.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TS 19857:2021(E)
Introduction
This document describes a test method to evaluate the ink setting characteristics of a specific ink/
substrate combination in offset lithographic printing.
Set-off is the transfer of ink from the front of one sheet to the back or the front of the next sheet.
Setting is the process of penetration of liquid ink components of low viscosity into the penetrable
substrate. These low-viscosity liquids within the ink are mineral oils, vegetable oils or esters of
vegetable oils. By separation from those low-viscous liquids, the remaining ink film solidifies. This is
combined with a varying change in the surface tack depending on the inks-varnish system and the
time. The surface tack usually increases at the begin of the setting and later-on drops to zero. Setting
is either the main drying mechanism for ink systems (e.g. news inks) or part of a multi-channel drying
mechanism (e.g. conventional sheet fed offset inks or heatset inks). The laboratory test for setting
performs a set-off print of the fresh print to a non-printed substrate at defined times. The ink transfer
to the non-printed substrate not only depends on the degree of solidification of the ink by setting, but
also on the actual level of tack of the original ink film. Thus, the test result is a combined measure.
The absorption properties of the paper are of great influence in offset lithography printing.
Inappropriate absorption can lead to numerous printing problems such as ink set-off, bad adhesion,
mottling, unpredictable tone value increase, poor rub resistance, damaging of first printed side on
perfecting presses after perfecting and others.
The more absorbent the paper is, the less time will be needed for the ink to set sufficiently for further
processing, but other properties can be affected adversely by fast ink setting. Very short times should
be used when testing the processing of wet sheets, e.g. in a perfector press. Longer times are used for
paper handling right after printing, and very long times are used for further processing such as folding
and cutting.
Depending on the purpose of the test, there are three options for the paper-ink combination:
— Reference ink on production paper;
— Production ink on reference paper;
— Production ink on production paper, which can be divided into the following, depending on the
application of the print:
— Set-off face-to-face (e.g. set-off after folding);
— Set-off face to back (e.g. set-off in a stack of paper).
© ISO 2021 – All rights reserved v
---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 19857:2021(E)
Paper, board and printing inks – Printability – Laboratory
test method for offset ink setting
1 Scope
1) 2)
This document describes a laboratory test method, using an IGT -type or a prüfbau -type printability
tester, for the preparation of specimens to evaluate the absorption rate of an ink on a substrate in offset
lithography by setting-off the printed surface to an unprinted surface.
This method describes testing with an amount of ink simulating either single colour or multi-colour
printing. The print and the set-off print (counter print) are made with interval times, between print and
set-off, common for the target process.
This method evaluates a particular ink and substrate combination.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 5-4, Photography and graphic technology — Density measurements — Part 4: Geometric conditions for
reflection density
ISO 2834-1, Graphic technology — Laboratory preparation of test prints — Part 1: Paste inks
ISO 2846-1, Graphic technology — Colour and transparency of printing ink sets for four-colour printing —
Part 1: Sheet-fed and heat-set web offset lithographic printing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
ink setting
process by which the ink dries by absorption and/or oxidation
3.2
set-off
effect produced when the ink on a print is transferred from the printed surface to another surface
1) These materials are available from IGT Testing Systems, www .igt .nl. This information is given for the convenience
of the users of this document and does not constitute an endorsement by ISO of the products. Equivalent products
may be used if they can be shown to lead to the same results.
2) These materials are available from prüfbau, Dr.-Ing. H. Dürner GmbH, www .pruefbau .de. This information is
given for the convenience of the users of this document and does not constitute an endorsement by ISO of the
products. Equivalent products may be used if they can be shown to lead to the same results.
© ISO 2021 – All rights reserved 1
---------------------- Page: 6 ----------------------
ISO/TS 19857:2021(E)
3.3
set-off paper
counter-paper
paper used to make a counter print for set-off (3.2) evaluation
3.4
ink film
amount of ink applied on the surface of the substrate to obtain the required optical
density of the print for the purpose of this test
2
Note 1 to entry: The amount is specified in g/m or in µm.
3.5
ink film
amount of ink applied on the surface of the printing forme for transfer to the
substrate in the printing operation
2
Note 1 to entry: The amount is specified in g/m or in µm. The ink film applied on the inking system is normally
about double the amount from the amount transferred to the substrate.
4 Apparatus and materials
4.1 Printing device
4.1.1 To perform this test, use a printability tester with one or two printing units capable of applying
a force (via a metal printing forme) on the printed sample independently from the preparation of the
printed sample. The interval time may be defined by the printing speed (and the distance between units)
or be adjusted by a timer.
Examples of commercially available printability testers that conform to these requirements are the
[8] [4]
prüfbau Multipurpose Printability Testing Instrument MZII, IGT AIC2-5 or any compatible tester. A
High Speed Inking Unit 4 is recommended for the IGT instruments while the inking unit is integrated in
the MZII. Refer to footnote further down.
4.1.2 IGT-type printing device having a sector with a radius of (85,0 ± 0,2) mm, incorporating a facility
enabling a packing (4.6) to be mounted under tension on the sector and a test piece to be mounted on the
packing. The sector shall be capable of being driven over a distance of 200 mm at a uniform speed.
The actual speed shall not differ by more than 5 % from the theoretical value over the workable range
as specified for the tester.
The force with which the printing forme contacts the test piece on the sector shall be adjustable. The
actual force shall not deviate by more than ±10 N from the set force.
The printing device should be properly calibrated with regard to printing speed and printing force
between the printing forme and the sector (see Annex A).
4.1.3 Prüfbau-type printing device having the possibility to run a substrate carrier, with a test piece
mounted on it, with uniform speed under the printing formes.
The actual speed shall not differ by more than 5 % from the theoretical value over the workable range
as specified for the tester.
The force with which the printing forme contacts the test piece on the sector shall be adjustable. The
actual force shall not deviate by more than ±10 N from the set force.
The printing device should be properly calibrated with regard to printing speed and printing force
between the printing forme and the sector (see Annex A).
2 © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TS 19857:2021(E)
4.2 Inking device
To distribute an even ink film of known thickness an inking device shall be used consisting of two or
more inking drums having contact with a top-roller. The ink distributing surface area A of the rollers
2
shall be known to the nearest 0,1 cm . Each inking arrangement shall incorporate one or more holders
on which the printing forme to be inked in can be mounted.
The distributing surface area, A, is calculated as in Formula (1):
n
A =⋅()π d ⋅l (1)
∑ nn
n=1
where
d is the diameter of roller or drum number (n);
n
l is the effective length of roller or drum number (n);
n
n is the number of rollers excluding the printing forme.
NOTE The lifetime of the rubber or elastomer-covered parts is limited, if properly handled, to a maximum of
approximately 3 years.
The transfer characteristics of rubber rollers can change by, e.g. using them for different applications,
inks, bad cleaning, unsuitable cleaning solvents and ageing. If tests are made using different top-rollers,
the top-rollers should be identical, and a test to determine the ink transfer might have to be performed.
4.3 Printing formes
4.3.1 For IGT-type testers, one or more aluminium printing formes, with known width and a diameter
of (65,0 ± 0,2) mm and a temperature-insulating handgrip shall be used: one for the ink to be applied,
and another one on which the set-off paper will be mounted. These printing formes shall be of the same
type. See Figure 1.
4.3.2 For prüfbau-type testers, a rubber blanket printing forme of the width of the whole printing area
and an aluminium printing forme with a smaller width than the blanket printing forme shall be used. The
rubber blanket printing forme is used for printing and the aluminium printing forme is used for set-off
counter printing. The prüfbau tester has a separate holder for the set-off paper so no wrapping of the set-
off paper around the aluminium printing forme is needed. The area not counter-printed will be used for
optical density evaluations of the original print.
Figure 1 — Example of a printing forme meeting the criteria of 4.3.1
© ISO 2021 – All rights reserved 3
---------------------- Page: 8 ----------------------
ISO/TS 19857:2021(E)
4.4 Ink pipette
To apply an accurate quantity of ink to the inking device an ink pipette having a minimum volume
of 2 ml and a resolution of at least 0,01 ml, but preferably 0,001 ml shall be used.
NOTE 1 If the inking device is equipped with a dispensing system with sufficient accuracy, no ink pipette is
needed.
NOTE 2 In principle, it is also possible to use the analytical balance to weigh the required amount of ink. In
that case, the required ink film thickness can be calculated considering the mass density of the ink.
4.5 Packing
In general, backing materials shall be suitable for the printing forme type. In the IGT-type printability
testers, rubber backing consisting of rubber blanket with a thickness of (1,70 ± 0,05) mm shall be used
since aluminium printing formes are used to make this test.
Refer to the printability tester manufacturer's instruction manual to mount and adjust backing tension.
Over time, a rubber packing will deteriorate and in general get harder o
...
TECHNICAL ISO/TS
SPECIFICATION 19857
First edition
Paper, board and printing inks –
Printability – Laboratory test method
for offset ink setting
Papier, carton et encres d'impression – Imprimabilité – Méthode
d'essai de laboratoire pour le séchage de l'encre offset
PROOF/ÉPREUVE
Reference number
ISO/TS 19857:2021(E)
©
ISO 2021
---------------------- Page: 1 ----------------------
ISO/TS 19857:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/TS 19857:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Apparatus and materials. 2
4.1 Printing device . 2
4.2 Inking device . 3
4.3 Printing formes . 3
4.4 Ink pipette . 4
4.5 Packing . 4
4.6 Substrate carrier . 4
4.7 Analytical balance. 4
4.8 Timer . 4
4.9 Densitometer . 4
4.10 Test paper . 5
4.11 Reference counter test strips . 5
4.12 Setting test ink . 5
4.13 Cleaning . 5
5 Test method . 5
5.1 Principle . 5
5.2 Test conditions . 6
5.2.1 Climatic conditions . 6
5.2.2 Settings of the printability tester . 6
5.2.3 Settings for the inking unit . 6
6 Procedure. 7
6.1 Preparation . 7
6.2 Preparational test for ink transfer determination. 7
6.3 Test execution on different instruments . 8
6.3.1 IGT-type testers . 8
6.3.2 Prüfbau type testers . . 9
7 Assessment . 9
8 Reporting .10
Annex A (informative) Checking the printing device and the inking device .12
Annex B (informative) Visualization of defects of used materials.13
Bibliography .21
© ISO 2021 – All rights reserved PROOF/ÉPREUVE iii
---------------------- Page: 3 ----------------------
ISO/TS 19857:2021(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/ directives).
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. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Subcommittee
SC 2, Test methods and quality specifications for paper and board.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/TS 19857:2021(E)
Introduction
This document describes a test method to evaluate the ink setting characteristics of a specific ink/
substrate combination in offset lithographic printing.
Set-off is the transfer of ink from the front of one sheet to the back or the front of the next sheet.
Setting is the process of penetration of liquid ink components of low viscosity into the penetrable
substrate. These low-viscosity liquids within the ink are mineral oils, vegetable oils or esters of
vegetable oils. By separation from those low-viscous liquids, the remaining ink film solidifies. This is
combined with a varying change in the surface tack depending on the inks-varnish system and the
time. The surface tack usually increases at the begin of the setting and later-on drops to zero. Setting
is either the main drying mechanism for ink systems (e.g. news inks) or part of a multi-channel drying
mechanism (e.g. conventional sheet fed offset inks or heatset inks). The laboratory test for setting
performs a set-off print of the fresh print to a non-printed substrate at defined times. The ink transfer
to the non-printed substrate not only depends on the degree of solidification of the ink by setting, but
also on the actual level of tack of the original ink film. Thus, the test result is a combined measure.
The absorption properties of the paper are of great influence in offset lithography printing.
Inappropriate absorption can lead to numerous printing problems such as ink set-off, bad adhesion,
mottling, unpredictable tone value increase, poor rub resistance, damaging of first printed side on
perfecting presses after perfecting and others.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE v
---------------------- Page: 5 ----------------------
TECHNICAL SPECIFICATION ISO/TS 19857:2021(E)
Paper, board and printing inks – Printability – Laboratory
test method for offset ink setting
1 Scope
1) 2)
This document describes a laboratory test method, using an IGT-type or a prüfbau -type printability
tester, for the preparation of specimens to evaluate the absorption rate of an ink on a substrate in offset
lithography by setting-off the printed surface to an unprinted surface.
This method describes testing with an amount of ink simulating either single colour or multi-colour
printing. The print and the set-off print (counter print) are made with interval times, between print and
set-off, common for the target process.
This method evaluates a particular ink and substrate combination.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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 5-4, Photography and graphic technology — Density measurements — Part 4: Geometric conditions for
reflection density
ISO 2469, Paper, board and pulps — Measurement of diffuse radiance factor (diffuse reflectance factor)
ISO 2834-1, Graphic technology — Laboratory preparation of test prints — Part 1: Paste inks
ISO 2846-1, Graphic technology — Colour and transparency of printing ink sets for four-colour printing —
Part 1: Sheet-fed and heat-set web offset lithographic printing
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
ink setting
process by which the ink dries by absorption and/or oxidation
3.2
set-off
effect produced when the ink on a print is transferred from the printed surface to another surface
1) These materials are available from IGT Testing Systems, www .igt .nl. This information is given for the convenience
of the users of this document and does not constitute an endorsement by ISO of the products. Equivalent products
may be used if they can be shown to lead to the same results.
2) These Materials are available from prüfbau GmbH, www .pruefbau .de. This information is given for the
convenience of the users of this document and does not constitute an endorsement by ISO of the products. Equivalent
products may be used if they can be shown to lead to the same results.
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 1
---------------------- Page: 6 ----------------------
ISO/TS 19857:2021(E)
3.3
set-off paper
counter-paper
paper used to make a counter print for set-off (3.2) evaluation
3.4
ink film
amount of ink applied on the surface of the substrate to obtain the required optical
density of the print for the purpose of this test
2
Note 1 to entry: The amount is specified in g/m or in µm.
3.5
ink film
amount of ink applied on the surface of the printing forme for transfer to the
substrate in the printing operation
2
Note 1 to entry: The amount is specified in g/m or in µm. The ink film applied on the inking system is normally
about double the amount from the amount transferred to the substrate.
4 Apparatus and materials
4.1 Printing device
4.1.1 To perform this test, use a printability tester with one or two printing units capable of applying
a force (via a metal printing forme) on the printed sample independently from the preparation of the
printed sample. The interval time may be defined by the printing speed (and the distance between units)
or be adjusted by a timer.
Examples of commercially available printability testers that conform to these requirements are the
[7] [3]
prüfbau Multipurpose Printability Testing Instrument MZII, IGT AIC2-5 or any compatible tester. A
High Speed Inking Unit 4 is recommended for the IGT instruments while the inking unit is integrated in
the MZII. Refer to footnote further down.
4.1.2 IGT-type printing device having a sector with a radius of (85,0 ± 0,2) mm, incorporating a facility
enabling a packing (4.6) to be mounted under tension on the sector and a test piece to be mounted on the
packing. The sector shall be capable of being driven over a distance of 200 mm at a uniform speed.
The actual speed shall not differ by more than 5 % from the theoretical value over the workable range
as specified for the tester.
The force with which the printing forme contacts the test piece on the sector shall be adjustable. The
actual force shall not deviate by more than ±10 N from the set force.
The printing device should be properly calibrated with regard to printing speed and printing force
between the printing forme and the sector (see Annex A).
4.1.3 Prüfbau-type printing device having the possibility to run a substrate carrier, with a test piece
mounted on it, with uniform speed under the printing formes.
The actual speed shall not differ by more than 5 % from the theoretical value over the workable range
as specified for the tester.
The force with which the printing forme contacts the test piece on the sector shall be adjustable. The
actual force shall not deviate by more than ±10 N from the set force.
The printing device should be properly calibrated with regard to printing speed and printing force
between the printing forme and the sector (see Annex A).
2 PROOF/ÉPREUVE © ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO/TS 19857:2021(E)
4.2 Inking device
To distribute an even ink film of known thickness an inking device shall be used consisting of two or
more inking drums having contact with a top-roller. The ink distributing surface area A of the rollers
2
shall be known to the nearest 0,1 cm . Each inking arrangement shall incorporate one or more holders
on which the printing forme to be inked in can be mounted.
The distributing surface area, A, is calculated as in Formula (1):
n
A =⋅()π d ⋅l (1)
∑ nn
n=1
where
d is the diameter of roller or drum number (n);
n
l is the effective length of roller or drum number (n);
n
n is the number of rollers excluding the printing forme.
NOTE The lifetime of the rubber or elastomer-covered parts is limited, if properly handled, to a maximum of
approximately 3 years.
The transfer characteristics of rubber rollers can change by, e.g. using them for different applications,
inks, bad cleaning, unsuitable cleaning solvents and ageing. If tests are made using different top-rollers,
the top-rollers should be identical, and a test to determine the ink transfer might have to be performed.
4.3 Printing formes
4.3.1 For IGT-type testers, one or more aluminium printing formes, with known width and a diameter
of (65,0 ± 0,2) mm and a temperature-insulating handgrip shall be used: one for the ink to be applied,
and another one on which the set-off paper will be mounted. These printing formes shall be of the same
type. See Figure 1.
4.3.2 For prüfbau-type testers, a rubber blanket printing forme of the width of the whole printing area
and an aluminium printing forme with a smaller width than the blanket printing forme shall be used. The
rubber blanket printing forme is used for printing and the aluminium printing forme is used for set-off
counter printing. The prüfbau tester has a separate holder for the set-off paper so no wrapping of the set-
off paper around the aluminium printing forme is needed. The area not counter-printed will be used for
optical density evaluations of the original print.
Figure 1 — Example of a printing forme meeting the criteria of 4.3.1
© ISO 2021 – All rights reserved PROOF/ÉPREUVE 3
---------------------- Page: 8 ----------------------
ISO/TS 19857:2021(E)
4.4 Ink pipette
To apply an accurate quantity of ink to the inking device an ink pipette having a minimum volume
of 2 ml and a resolution of at least 0,01 ml, but preferably 0,001 ml shall be used.
NOTE 1 If the inking device is equipped with a dispensing system with sufficient accuracy, no ink pipette is
needed.
NOTE 2 In principle, it is also possible to use the analytical balance to weigh the required amount of ink. In
that case, the required ink film thickness can be calculated considering the mass density of the ink.
4.5 Packing
In general, backing materials shall be suitable for the printing forme type. In the IGT-type printability
testers, rubber backing consisting of rubber blanket with a thickness of (1,70 ± 0,05) mm shall be used
since aluminium printing formes are used to make this test.
Refer to the printability tester manufacturer's instruction manual to mount and adjust backing tension.
Over time, a rubber packing will deteriorate and in general get harder or get cracked. Also, dents can
occur where smaller printing formes are used to over-print prints made with wider printing formes. In
either case, make sure to replace the rubber before these effects take place. Annex B shows some of the
possible defects.
4.6 Substrate carrier
A rigid carrier covered with a special rubber blanket with a thickness and hardness required for the
used printability tester and for the used substrate thickness.
Over time a rubber will deteriorate and in general get harder or get cracked. Also, dents can occur where
smaller printing formes are used to over-print prints made with wider printing formes. In either
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.