Graphic technology — Processless lithographic plates — Part 1: Evaluation methods for characteristics and performance

This document applies to processless lithographic plates and specifies evaluation methods for lithographic plate characteristics, on-press development performance, usability and print image quality. It specifies measurement conditions for materials and equipment and provides guidelines for the selection of suitable processless lithographic plates by a printing organization and requirements for comparative assessment tests. The assessment of waterless lithographic plates is out of scope of this document.

Technologie graphique — Plaques lithographiques sans traitement — Partie 1: Méthodes d'évaluation des caractéristiques et des performances

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Published
Publication Date
11-Nov-2021
Current Stage
6060 - International Standard published
Start Date
12-Nov-2021
Completion Date
12-Nov-2021
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INTERNATIONAL ISO
STANDARD 24487-1
First edition
2021-11
Graphic technology — Processless
lithographic plates —
Part 1:
Evaluation methods for characteristics
and performance
Technologie graphique — Plaques lithographiques sans traitement —
Partie 1: Méthodes d'évaluation des caractéristiques et des
performances
Reference number
ISO 24487-1:2021(E)
© ISO 2021
---------------------- Page: 1 ----------------------
ISO 24487-1:2021(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
© ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 24487-1:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Test procedure .......................................................................................................................................................................................................2

4.1 General ........................................................................................................................................................................................................... 2

4.2 Test environment ................................................................................................................................................................................. 2

4.3 Plate imaging ............................................................................................................................................................................................ 2

4.4 Pre-dampening amount ........................................................................................................................................... ....................... 4

4.5 Pre-inking amount .............................................................................................................................................................................. 4

4.6 Ink selection .............................................................................................................................................................................................. 4

4.7 Substrate selection.............................................................................................................................................................................. 4

4.8 Fountain solution ................................................................................................................................................................................. 5

4.9 Press preparation and control .................................................................................................................................................. 5

4.9.1 Press preparation print run ..................................................................................................................................... 5

4.9.2 Reference printing aim values ............................................................................................................................... 5

4.10 Printing method .................................................................................................................................................................................... 6

4.11 Plate exposure to light ..................................................................................................................................................................... 6

5 Assessment methods ....................................................................................................................................................................................... 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 On-press development ..................................................................................................................................................................... 6

5.2.1 Number of sheets required for on-press development ..................................................................... 6

5.2.2 Assessment of non-image area............................................................................................................................... 7

5.2.3 Assessment of solid area ............................................................................................................................................. 8

5.2.4 Assessment of intermediate tones...................................................................................................................... 8

5.3 Abrasion resistance ......... .................................................................................................................................. ................................. 9

5.4 Resistance to toning .......................................................................................................................................................................... 9

5.5 Chemical resistance ....................................................................................................................................................................... 11

5.5.1 General ..................................................................................................................................................................................... 11

5.5.2 Rub test ....................................................................................................................................................................................12

5.5.3 Drop test .................................................................................................................................................................................12

5.6 Plate performance for stop and restart .........................................................................................................................12

6 Reporting requirements ...........................................................................................................................................................................12

Annex A (informative) Examples of measurement method and results .....................................................................14

Annex B (informative) Example of evaluation results and classification .................................................................26

Annex C (informative) Examples of quality grade reporting .................................................................................................27

Bibliography .............................................................................................................................................................................................................................29

iii
© ISO 2021 – All rights reserved
---------------------- Page: 3 ----------------------
ISO 24487-1:2021(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 130, Graphic technology.

A list of all parts in the ISO 24487 series can be found on the ISO website.

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.
© ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO 24487-1:2021(E)
Introduction

Processless plates represent a simple way to prepare plates in prepress. Once a plate has been imaged,

it is mounted directly on the press where the plate coating is removed on start-up of the press. This

approach eliminates the plate processor, associated chemistry, energy required to power the processor,

water, and waste from plate preparation.

Perceived benefits of processless plates include ease of use and improved speed of production compared

to traditional plate preparation systems since there is no need for a plate processor or finishing unit.

Processless plates are mounted directly on press once imaged. Since costs associated with processors

and finishing units, including developer and cleaning solution, time and labour are eliminated, printing

using processless plates is perceived as a low-cost method.

The unique characteristic of processless plates is on-press development. After the exposure process

by computer to plate (CTP) exposing equipment, the non-image area of the photosensitive layer is

physically removed along with the ink and the fountain solution of the press.
The removal procedure is as follows.

— When the press is started, fountain solution and ink are applied. The fountain solution permeates

the unexposed (non-image) area of the photosensitive layer. The unexposed photosensitive layer is

then peeled from the base material by the viscosity of the printing ink.

— This peeled photosensitive layer is finely dispersed into the ink which is discharged on paper from

the press in the usual way. Parts of the peeled layer are also discharged into the fountain solution.

© ISO 2021 – All rights reserved
---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 24487-1:2021(E)
Graphic technology — Processless lithographic plates —
Part 1:
Evaluation methods for characteristics and performance
1 Scope

This document applies to processless lithographic plates and specifies evaluation methods for

lithographic plate characteristics, on-press development performance, usability and print image quality.

It specifies measurement conditions for materials and equipment and provides guidelines for the

selection of suitable processless lithographic plates by a printing organization and requirements for

comparative assessment tests.

The assessment of waterless lithographic plates is out of scope of this document.

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 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

ISO 12647-2, Graphic technology — Process control for the production of half-tone colour separations,

proof and production prints — Part 2: Offset lithographic processes

ISO 13655, 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.

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 https:// www .electropedia .org/
3.1
processless plate

plate loaded directly on to a printing press following exposure without any intermediate processing

step other than mechanical processes such as plate punching and bending

Note 1 to entry: Intermediate processing steps typically include plate development, cleaning, fixing (or

desensitization) and other treatments

Note 2 to entry: Strictly speaking, these plates are 'processed' on press using the press fountain solution and ink.

3.2
pre-dampening amount
fountain solution amount used to wet plates prior to printing
© ISO 2021 – All rights reserved
---------------------- Page: 6 ----------------------
ISO 24487-1:2021(E)
3.3
pre-inking amount
ink amount applied to plates prior to printing
4 Test procedure
4.1 General

Printing machines in use today differ in physical structure, fountain technology and ink delivery

systems. The test conditions in this document are designed to be practical and to show significant

differentiation between performance of different processless plate technologies.

Test conditions have been chosen to control key factors that have an impact on processless plates

performance.
Two categories of testing are anticipated by this document.

a) Individual test: testing by a printer who wishes to choose the most suitable plate for his purpose

and for this category of test, the production methods and materials used for testing should be those

used by the printer for print production.

b) Comparative test: scientific testing to allow the performance of printing plates to be compared

to one another and for this category, the testing requires the use of specified test materials and

methods which in some cases may be specified by the press or plates manufacturer.

Unless explicitly indicated, requirements shall be applied to both testing categories.

4.2 Test environment
The temperature of the printing room shall be 24 °C ± 2 °C.
The relative humidity of the printing room shall be (55 ± 10) % RH.
4.3 Plate imaging

Printing plates shall be prepared to include the following content. Additional inked content shall be

added in such a way as to ensure approximately equal inking across the plate of between 20 % to 40 %

coverage.

A CMYK test form with a set of rectangular or square patches shall be prepared comprising: a solid

(100 %) patch in each process colour, and patches of intermediate tones from 10 % to 70 % tone value

in each process colour. A region of at least 100 mm × 150 mm of the sheet shall be left blank (the non-

image area).

Each patch should have a minimum size of 10 mm × 10 mm and patches should be spaced by a minimum

of 5 mm. Where visual assessment is required, patches should have a minimum size of 40 mm × 40 mm.

The plate image area shall have a large region of approximately half the total image size where no marks

are imaged. An example test form is shown in Figure 1.

NOTE 1 The minimum size for each patch has been specified so that the patches can be measured easily. The

minimum spacing of patches is required to allow visual assessment of toning between printed elements.

© ISO 2021 – All rights reserved
---------------------- Page: 7 ----------------------
ISO 24487-1:2021(E)
Key
A preferred printing direction
Figure 1 — Example CMYK test form

The test form should be imaged in several positions and with different orientations. When oriented in

the press direction, it shall be aligned with the preferred printing direction as indicated.

NOTE 2 Where a subset of the process inks is to be tested, not all plates need to be imaged. For example, to test

the performance with cyan ink, only the cyan plate needs to be imaged.

The plates shall be exposed as recommended by the manufacturer for optimum image sensitivity and

should be adjusted to ensure that the halftone dot area on plate corresponds to patch tone value.

When printing is not 4-colour (CMYK), for example monochrome printing or printing of spot inks or

varnish, a test chart comprising the set of process colours generally used in print production shall be

used.

Where abrasion resistance tests are to be performed, a monochrome test form comprising seven

sets of the patches shall be imaged. This test is generally performed on the black plate, but the same

monochrome image may also be used to image the cyan, magenta or yellow plate. An example of a

suitable test form is shown in Figure 2. Sets of patches shall be separated sufficiently to allow abrasion

resistance testing to be performed on one set without affecting any other set.
This test form may also be used when testing chemical resistance.
© ISO 2021 – All rights reserved
---------------------- Page: 8 ----------------------
ISO 24487-1:2021(E)
Key
A preferred printing direction
B abrasion direction
Figure 2 — Example abrasion resistance test form

When printing CMYK, all test forms shall be prepared and printed to meet the requirements of

ISO 12647-2 with the exception of the tone value increase which should not be adjusted from the

natural behaviour of the printing press. Additional content necessary for process control should be

added as required. The reference paper type that is closest to the paper actually used for printing shall

be identified and reported. When comparative testing is performed, a half-tone screen ruling of 60 cm

(approximately 150 lines per inch) should be used.
4.4 Pre-dampening amount

The pre-dampening amount should be as small as possible and shall be no greater than the recommended

value from the press vendor.
4.5 Pre-inking amount

The pre-inking amount shall be set to the recommended value from the plate manufacturer or press

vendor.
4.6 Ink selection

When individual testing is performed to determine whether the plate is suitable for a printing operation,

the inks used for testing should be the same as are typically used for production.

When comparative testing is performed, inks conforming to ISO 2846-1 shall be used.

For the evaluation of resistance to toning, a low viscosity and low tack ink with a large content of

varnish should be used.
Details of the inks used shall be reported.

NOTE Low viscosity and low tack inks show more differences when comparing processless plates.

4.7 Substrate selection

When individual testing is performed to determine whether the plate is suitable for a printing operation,

the substrates used for testing should be the same as are typically used for production.

When comparative testing is performed, paper for the appropriate ISO 12647-2 printing condition shall

be used. Where possible, an environmentally friendly paper such as recycled paper and FSC certified

paper should be used.
© ISO 2021 – All rights reserved
---------------------- Page: 9 ----------------------
ISO 24487-1:2021(E)
Details of the substrate used shall be reported.
4.8 Fountain solution

When individual testing is performed to determine whether the plate is suitable for a printing operation,

the fountain solution used for testing should be the same as are typically used for production.

When comparative testing is performed, a fountain solution recommended by the press manufacturer

shall be used. Where possible, an environmentally friendly fountain solution should be used. A list of

fountain concentrates tested by Fogra and approved by the printing press manufacturers is given in

Reference [2].

Dilution of the fountain solution shall be made as recommended by the printing press manufacturer.

The fountain solution and dilution amount used shall be reported.
4.9 Press preparation and control
4.9.1 Press preparation print run

The number of sheets required for plate development depends on the press condition when the print

run starts and can vary by more than a factor of two. To avoid this problem, two sets of identical plates

shall be prepared. The first set shall be used for a press preparation print run of at least 300 sheets

during which ink key settings are established and the second set shall be used for the test print run.

During the press preparation press run, the press settings should be established according to the press

and plate manufacturer's recommendation. The blanket shall then be washed and dried before the

plates to be tested are fitted to the press and the testing begins.

NOTE The start-up procedure according to the plate manufacturer’s and the press manufacturer’s

recommendation can be different for each press or plate.

The press shall be adjusted to achieve the printing aims within the deviation tolerances as specified in

ISO 12647-2 for the solid cyan, magenta, yellow and black process colorants and all patches are within

the variation tolerances.

Printing speed shall be the speed generally used for print production or a standard setting as

recommended by the press manufacturer. Press speed shall be reported.

Other press parameters such as fountain solution cooling temperature, ink roller cooling temperature,

blanket, water supply system, slip ratio between fountain solution rollers and impression throw-in

should be operated as recommended by the press manufacturer. In cases where the press is operated

differently from that recommended by the manufacturer, the differences shall be reported.

Where available, press manufacturer recommended programs for processless plates should be

used. Where no such recommendation exists, the same press condition as is used for printing using

conventional plates shall be used.

All settings and materials necessary to repeat the result of the press preparation print run shall be

reported.
4.9.2 Reference printing aim values

A set of sheets shall be selected from the end of this press preparation print run that are within the

specified tolerance and shall be measured to establish reference aim values for all coloured patches and

for the unprinted substrate.
© ISO 2021 – All rights reserved
---------------------- Page: 10 ----------------------
ISO 24487-1:2021(E)
4.10 Printing method

Using the printing procedure recommended by the printing press manufacturer or, when individual

tests are performed, by the standard printing method used by the printing operation, approximately

100 sheets should be printed after on-press development is observed by the press operator to be

complete.

NOTE Printing procedures include adjustment of ink roller and dampening roller settings, adjustment of

spacing between plate and blanket cylinder, balance between water and ink, and blanket freshening.

Where assessment of toning, chemical resistance and press stop-and-restart is performed, additional

prints shall be made as follows. Print an additional 1 000 sheets using the standard printing procedure

before stopping the press. The last 30 sheets before stopping shall be collected. The press shall be

stopped for one hour. The press shall be restarted and at least 100 additional sheets printed.

The press state during the period where the press is stopped can affect the stop-and-restart testing.

The best result can be different for each press or plate type and so where they exist, the manufacturers'

recommendations for press stop-and-restart should be used.

The last 30 sheets collected before the press is stopped are used to evaluate toning performance.

The last 30 sheets collected before the press is stopped, along with sheets 70 to 100 printed following

the restart, are used to evaluate chemical resistance and stop-and-restart performance.

4.11 Plate exposure to light

The performance of some plates is affected when exposed to light. This can happen when plates are

prepared and placed next to the press during a previous print run as is often done.

In order to test the effect of light exposure on the plates, a set of plates shall be produced and exposed

to typical pressroom lighting for a period of 1 h.

Where comparative testing is performed, the lighting condition of ISO 3664 P2 should be used.

Plates for this test should be new and stored in a dark place before the test begins.

5 Assessment methods
5.1 General

The following test methods are designed to evaluate processless plates. Measurements shall be made in

accordance with ISO 13655. ISO 3664 viewing condition P2 should be used for visual assessment.

NOTE Some of these test methods can also be used to evaluate standard process plate properties.

Examples of reporting of results are shown in Annex B.
5.2 On-press development
5.2.1 Number of sheets required for on-press development

Figure 3 shows the typical relationship between the number of sheets printed and the CIELAB colour

change for each region of the plate.

NOTE The curve shapes shown in Figure 3 can vary significantly from one press to another, can depend on

the processless plates, and can depend on the start-up condition of the press.
© ISO 2021 – All rights reserved
---------------------- Page: 11 ----------------------
ISO 24487-1:2021(E)
Key
X number of sheets
Y ΔE from substrate
1 colour change of solid image area
2 colour change of intermediate tones
3 colour change of non-image area
Figure 3 — Typical colour coordinates and tone values by number of sheets

The press shall be started, and the colour of regions 1, 2 and 3 shall be monitored until:

— the colour of regions 1 and 2 match the printing aim values established in 4.9.1 to within the variation

tolerances of ISO 12647-2,
— no ink is visible on the non-image area (region 3), and

— the colour of the unprinted sheet matches the reference (see 4.9.1) to within the variation tolerance

specified in ISO 12647-2.

The set of sheets printed from the time the press is started shall be numbered and the sheet number

where all conditions are met shall be identified. The number of this sheet is defined as the number of

sheets required for on-press development.
Details of how to print and measure the sheets are provided in Annex A.
5.2.2 Assessment of non-image area

Assessment of the non-image area provides an indication of the effective removal of the photosensitive

layer. The maximum density of the non-image area generated during the on-press development period

affects the toning in the printing press and the quality of the prints and provides a measure of the

effectiveness of on-press development.

Sheets shall be assessed by visual inspection using a loupe to ensure that no ink is visible on the

unprinted region. Care shall be taken to check that the edges of the printed region are sharply defined

with no residual ink beyond the edge.

The number of sheets required to reach the point where the printed matter does not have any visible

ink shall be recorded along with the maximum CIELAB76 colour difference between the print area and

the unprinted substrate colour on any of the sheets printed from the time the press is started.

When the ink spreads over the entire surface of the plate, excess ink contaminates the printing press

and can cause various quality failures. The maximum ink density in the non-image area provides a

measure of the effectiveness of on-press development.
© ISO 2021 – All rights reserved
---------------------- Page: 12 ----------------------
ISO 24487-1:2021(E)
Key
1 exposed plate
2 plate covered with fountain solution
3 plate covered with ink
4 plate with ink remaining only on halftone dots
Figure 4 — Fountain solution and ink spread

Figure 4 shows the steps in the formation of the non-image area. The exposed plate is co

...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 24487-1
ISO/TC 130
Graphic technology — Processless
Secretariat: SAC
plates —
Voting begins on:
2021-08-06
Part 1:
Voting terminates on:
Evaluation methods for characteristics
2021-10-01
and performance
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 24487-1:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 24487-1:2021(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/FDIS 24487-1:2021(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Test procedure ........................................................................................................................................................................................................ 2

4.1 General ........................................................................................................................................................................................................... 2

4.2 Test environment .................................................................................................................................................................................. 2

4.3 Plate imaging ............................................................................................................................................................................................ 2

4.4 Pre-dampening amount .................................................................................................................................................................. 4

4.5 Pre-inking amount ............................................................................................................................................................................... 4

4.6 Ink selection .............................................................................................................................................................................................. 4

4.7 Substrate selection .............................................................................................................................................................................. 4

4.8 Fountain solution .................................................................................................................................................................................. 5

4.9 Press preparation and control ................................................................................................................................................... 5

4.9.1 Press preparation print run ................................................................................................................................... 5

4.9.2 Reference printing aim values .............................................................................................................................. 5

4.10 Printing method ..................................................................................................................................................................................... 6

4.11 Plate exposure to light ...................................................................................................................................................................... 6

5 Assessment methods ........................................................................................................................................................................................ 6

5.1 General ........................................................................................................................................................................................................... 6

5.2 On-press development ..................................................................................................................................................................... 6

5.2.1 Number of sheets required for on-press development .................................................................. 6

5.2.2 Assessment of non-image area ............................................................................................................................ 7

5.2.3 Assessment of solid area ........................................................................................................................................... 8

5.2.4 Assessment of intermediate tones ................................................................................................................... 8

5.3 Abrasion resistance ............................................................................................................................................................................. 9

5.4 Resistance to toning ........................................................................................................................................................................... 9

5.5 Chemical resistance ........................................................................................................................................................................11

5.5.1 General...................................................................................................................................................................................11

5.5.2 Rub test .................................................................................................................................................................................12

5.5.3 Drop test ...............................................................................................................................................................................12

5.6 Plate performance for stop and restart ..........................................................................................................................12

6 Reporting requirements ............................................................................................................................................................................12

Annex A (informative) Examples of measurement method and results .......................................................................14

Annex B (informative) Example of evaluation results and classification ....................................................................26

Annex C (informative) Examples of quality grade reporting ....................................................................................................27

Bibliography .............................................................................................................................................................................................................................29

© ISO 2021 – All rights reserved iii
---------------------- Page: 3 ----------------------
ISO/FDIS 24487-1:2021(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 130, Graphic technology.

A list of all parts in the ISO 24487 series can be found on the ISO website.

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/FDIS 24487-1:2021(E)
Introduction

Processless plates represent a simple way to prepare plates in prepress. Once a plate has been imaged,

it is mounted directly on the press where the plate coating is removed on start-up of the press. This

approach eliminates the plate processor, associated chemistry, energy required to power the processor,

water, and waste from plate preparation.

Perceived benefits of processless plates include ease of use and improved speed of production compared

to traditional plate preparation systems since there is no need for a plate processor or finishing unit.

Processless plates are mounted directly on press once imaged. Since costs associated with processors

and finishing units, including developer and cleaning solution, time and labour are eliminated, printing

using processless plates is perceived as a low-cost method.

The unique characteristic of processless plates is on-press development. After the exposure process

by computer to plate (CTP) exposing equipment, the non-image area of the photosensitive layer is

physically removed along with the ink and the fountain solution of the press.
The removal procedure is as follows.

— When the press is started, fountain solution and ink are applied. The fountain solution permeates

the unexposed (non-image) area of the photosensitive layer. The unexposed photosensitive layer is

then peeled from the base material by the viscosity of the printing ink.

— This peeled photosensitive layer is finely dispersed into the ink which is discharged on paper from

the press in the usual way. Parts of the peeled layer are also discharged into the fountain solution.

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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 24487-1:2021(E)
Graphic technology — Processless plates —
Part 1:
Evaluation methods for characteristics and performance
1 Scope

This document applies to processless lithographic plates and specifies evaluation methods for

lithographic plate characteristics, on-press development performance, usability and print image quality.

It specifies measurement conditions for materials and equipment and provides guidelines for the

selection of suitable processless lithographic plates by a printing organization and requirements for

comparative assessment tests.

The assessment of waterless lithographic plates is out of scope of this document.

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 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

ISO 12647-2, Graphic technology — Process control for the production of half-tone colour separations,

proof and production prints — Part 2: Offset lithographic processes

ISO 13655, 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.

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 https:// www .electropedia .org/
3.1
processless plate

plate loaded directly on to a printing press following exposure without any intermediate processing

step other than mechanical processes such as plate punching and bending

Note 1 to entry: Intermediate processing steps typically include plate development, cleaning, fixing (or

desensitization) and other treatments

Note 2 to entry: Strictly speaking, these plates are 'processed' on press using the press fountain solution and ink.

3.2
pre-dampening amount
fountain solution amount used to wet plates prior to printing
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ISO/FDIS 24487-1:2021(E)
3.3
pre-inking amount
ink amount applied to plates prior to printing
4 Test procedure
4.1 General

Printing machines in use today differ in physical structure, fountain technology and ink delivery

systems. The test conditions in this document are designed to be practical and to show significant

differentiation between performance of different processless plate technologies.

Test conditions have been chosen to control key factors that have an impact on processless plates

performance.
Two categories of testing are anticipated by this document.

a) Individual test: testing by a printer who wishes to choose the most suitable plate for his purpose

and for this category of test, the production methods and materials used for testing should be those

used by the printer for print production.

b) Comparative test: scientific testing to allow the performance of printing plates to be compared

to one another and for this category, the testing requires the use of specified test materials and

methods which in some cases may be specified by the press or plates manufacturer.

Unless explicitly indicated, requirements shall be applied to both testing categories.

4.2 Test environment
The temperature of the printing room shall be 24 °C ± 2 °C.
The relative humidity of the printing room shall be (55 ± 10) % RH.
4.3 Plate imaging

Printing plates shall be prepared to include the following content. Additional inked content shall be

added in such a way as to ensure approximately equal inking across the plate of between 20 % to 40 %

coverage.

A CMYK test form with a set of rectangular or square patches shall be prepared comprising: a solid

(100 %) patch in each process colour, and patches of intermediate tones from 10 % to 70 % tone value

in each process colour. A region of at least 100 mm × 150 mm of the sheet shall be left blank (the non-

image area).

Each patch should have a minimum size of 10 mm × 10 mm and patches should be spaced by a minimum

of 5 mm. Where visual assessment is required, patches should have a minimum size of 40 mm x 40 mm.

The plate image area shall have a large region of approximately half the total image size where no marks

are imaged. An example test form is shown in Figure 1.

NOTE 1 The minimum size for each patch has been specified so that the patches can be measured easily. The

minimum spacing of patches is required to allow visual assessment of toning between printed elements.

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ISO/FDIS 24487-1:2021(E)
Key
A preferred printing direction
Figure 1 — Example CMYK test form

The test form should be imaged in several positions and with different orientations. When oriented in

the press direction, it shall be aligned with the preferred printing direction as indicated.

NOTE 2 Where a subset of the process inks is to be tested, not all plates need to be imaged. For example, to test

the performance with cyan ink, only the cyan plate needs to be imaged.

The plates shall be exposed as recommended by the manufacturer for optimum image sensitivity and

should be adjusted to ensure that the halftone dot area on plate corresponds to patch tone value.

When printing is not 4-colour (CMYK), for example monochrome printing or printing of spot inks or

varnish, a test chart comprising the set of process colours generally used in print production shall be

used.

Where abrasion resistance tests are to be performed, a monochrome test form comprising seven

sets of the patches shall be imaged. This test is generally performed on the black plate, but the same

monochrome image may also be used to image the cyan, magenta or yellow plate. An example of a

suitable test form is shown in Figure 2. Sets of patches shall be separated sufficiently to allow abrasion

resistance testing to be performed on one set without affecting any other set.
This test form may also be used when testing chemical resistance.
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ISO/FDIS 24487-1:2021(E)
Key
A preferred printing direction
B abrasion direction
Figure 2 — Example abrasion resistance test form

When printing CMYK, all test forms shall be prepared and printed to meet the requirements of

ISO 12647-2 with the exception of the tone value increase which should not be adjusted from the

natural behaviour of the printing press. Additional content necessary for process control should be

added as required. The reference paper type that is closest to the paper actually used for printing shall

be identified and reported. When comparative testing is performed, a half-tone screen ruling of 60 cm

(approximately 150 lines per inch) should be used.
4.4 Pre-dampening amount

The pre-dampening amount should be as small as possible and shall be no greater than the recommended

value from the press vendor.
4.5 Pre-inking amount

The pre-inking amount shall be set to the recommended value from the plate manufacturer or press

vendor.
4.6 Ink selection

When individual testing is performed to determine whether the plate is suitable for a printing operation,

the inks used for testing should be the same as are typically used for production.

When comparative testing is performed, inks conforming to ISO 2846-1 shall be used.

For the evaluation of resistance to toning, a low viscosity and low tack ink with a large content of

varnish should be used.
Details of the inks used shall be reported.

NOTE Low viscosity and low tack inks show more differences when comparing processless plates.

4.7 Substrate selection

When individual testing is performed to determine whether the plate is suitable for a printing operation,

the substrates used for testing should be the same as are typically used for production.

When comparative testing is performed, paper for the appropriate ISO 12647-2 printing condition shall

be used. Where possible, an environmentally friendly paper such as recycled paper and FSC certified

paper should be used.
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ISO/FDIS 24487-1:2021(E)
Details of the substrate used shall be reported.
4.8 Fountain solution

When individual testing is performed to determine whether the plate is suitable for a printing operation,

the fountain solution used for testing should be the same as are typically used for production.

When comparative testing is performed, a fountain solution recommended by the press manufacturer

shall be used. Where possible, an environmentally friendly fountain solution should be used. A list of

fountain concentrates tested by Fogra and approved by the printing press manufacturers is given in

Reference [2].

Dilution of the fountain solution shall be made as recommended by the printing press manufacturer.

The fountain solution and dilution amount used shall be reported.
4.9 Press preparation and control
4.9.1 Press preparation print run

The number of sheets required for plate development depends on the press condition when the print

run starts and can vary by more than a factor of two. To avoid this problem, two sets of identical plates

shall be prepared. The first set shall be used for a press preparation print run of at least 300 sheets

during which ink key settings are established and the second set shall be used for the test print run.

During the press preparation press run, the press settings should be established according to the press

and plate manufacturer's recommendation. The blanket shall then be washed and dried before the

plates to be tested are fitted to the press and the testing begins.

NOTE The start-up procedure according to the plate manufacturer’s and the press manufacturer’s

recommendation can be different for each press or plate.

The press shall be adjusted to achieve the printing aims within the deviation tolerances as specified in

ISO 12647-2 for the solid cyan, magenta, yellow and black process colorants and all patches are within

the variation tolerances.

Printing speed shall be the speed generally used for print production or a standard setting as

recommended by the press manufacturer. Press speed shall be reported.

Other press parameters such as fountain solution cooling temperature, ink roller cooling temperature,

blanket, water supply system, slip ratio between fountain solution rollers and impression throw-in

should be operated as recommended by the press manufacturer. In cases where the press is operated

differently from that recommended by the manufacturer, the differences shall be reported.

Where available, press manufacturer recommended programs for processless plates should be

used. Where no such recommendation exists, the same press condition as is used for printing using

conventional plates shall be used.

All settings and materials necessary to repeat the result of the press preparation print run shall be

reported.
4.9.2 Reference printing aim values

A set of sheets shall be selected from the end of this press preparation print run that are within the

specified tolerance and shall be measured to establish reference aim values for all coloured patches and

for the unprinted substrate.
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ISO/FDIS 24487-1:2021(E)
4.10 Printing method

Using the printing procedure recommended by the printing press manufacturer or, when individual

tests are performed, by the standard printing method used by the printing operation, approximately

100 sheets should be printed after on-press development is observed by the press operator to be

complete.

NOTE Printing procedures include adjustment of ink roller and dampening roller settings, adjustment of

spacing between plate and blanket cylinder, balance between water and ink, and blanket freshening.

Where assessment of toning, chemical resistance and press stop-and-restart is performed, additional

prints shall be made as follows. Print an additional 1 000 sheets using the standard printing procedure

before stopping the press. The last 30 sheets before stopping shall be collected. The press shall be

stopped for one hour. The press shall be restarted and at least 100 additional sheets printed.

The press state during the period where the press is stopped can affect the stop-and-restart testing.

The best result can be different for each press or plate type and so where they exist, the manufacturers'

recommendations for press stop-and-restart should be used.

The last 30 sheets collected before the press is stopped are used to evaluate toning performance.

The last 30 sheets collected before the press is stopped, along with sheets 70 to 100 printed following

the restart, are used to evaluate chemical resistance and stop-and-restart performance.

4.11 Plate exposure to light

The performance of some plates is affected when exposed to light. This can happen when plates are

prepared and placed next to the press during a previous print run as is often done.

In order to test the effect of light exposure on the plates, a set of plates shall be produced and exposed

to typical pressroom lighting for a period of 1 h.

Where comparative testing is performed, the lighting condition of ISO 3664 P2 should be used.

Plates for this test should be new and stored in a dark place before the test begins.

5 Assessment methods
5.1 General

The following test methods are designed to evaluate processless plates. Measurements shall be made in

accordance with ISO 13655. ISO 3664 viewing condition P2 should be used for visual assessment.

NOTE Some of these test methods can also be used to evaluate standard process plate properties.

Examples of reporting of results are shown in Annex B.
5.2 On-press development
5.2.1 Number of sheets required for on-press development

Figure 3 shows the typical relationship between the number of sheets printed and the CIELAB colour

change for each region of the plate.

NOTE The curve shapes shown in Figure 3 can vary significantly from one press to another, can depend on

the processless plates, and can depend on the start-up condition of the press.
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ISO/FDIS 24487-1:2021(E)
Key
X number of sheets
Y ΔE from substrate
1 colour change of solid image area
2 colour change of intermediate tones image of non-image
3 colour change or non-image area
Figure 3 — Typical colour coordinates and tone values by number of sheets

The press shall be started, and the colour of regions a, b and c shall be monitored until:

— the colour of regions a and b match the printing aim values established in 4.9.1 to within the variation

tolerances of ISO 12647-2,
— no ink is visible on the non-image area (region c), and

— the colour of the unprinted sheet matches the reference (see 4.9.1) to within the variation tolerance

specified in ISO 12647-2.

The set of sheets printed from the time the press is started shall be numbered and the sheet number

where all conditions are met shall be identified. The number of this sheet is defined as the number of

sheets required for on-press development.
Details of how to print and measure the sheets are provided in Annex A.
5.2.2 Assessment of non-image area

Assessment of the non-image area provides an indication of the effective removal of the photosensitive

layer. The maximum density of the non-image area generated during the on-press development period

affects the toning in the printing press and the quality of the prints and provides a measure of the

effectiveness of on-press development.

Sheets shall be assessed by visual inspection using a loupe to ensure that no ink is visible on the

unprinted region. Care shall be taken to check that the edges of the printed region are sharply defined

with no residual ink beyond the edge.

The number of sheets required to reach the point where the printed matter does not have any visible

ink shall be recorded along with the maximum CIELAB76 colour difference between the print area and

the unprinted substrate colour on any of the sheets printed from the time the press is started.

When the ink spreads over the entire surface of the plate, excess ink contaminates the printing press

and can cau
...

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