ISO/TS 21139-21:2019

TECHNICAL ISO/TS
SPECIFICATION 21139-21
First edition
2019-07
Permanence and durability of
commercial prints —
Part 21:
In-window display — Light and ozone
stability
Permanence et durabilité des impressions commerciales —
Partie 21: Fenêtre de visualisation — Stabilité à la lumière et à l'ozone
Reference number
ISO/TS 21139-21:2019(E)
©
ISO 2019

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ISO/TS 21139-21:2019(E)

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ISO/TS 21139-21:2019(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Use profile . 2
4.1 General . 2
4.2 Environmental light condition . 2
4.3 Environmental ozone condition . 2
5 Test method . 2
5.1 General . 2
5.2 Sample preparation . 3
5.2.1 Outline . 3
5.2.2 Test target . 3
5.2.3 Storage conditions between printing and light or ozone exposure test . 3
5.2.4 Reference samples . 3
5.2.5 Backing of the specimens . 3
5.3 Light exposure . 3
5.3.1 Outline . 3
5.3.2 Spectral power distribution . 3
5.3.3 Light intensity . 4
5.3.4 Temperature and humidity . 4
5.3.5 Duration of the light exposures . 4
5.4 Ozone test . 4
5.4.1 Outline . 4
5.4.2 Apparatus . 4
5.4.3 Test procedure . 4
5.4.4 Test conditions. 4
6 Measurement . 5
6.1 General . 5
6.2 Measurement conditions . . 5
6.3 Calculation of colour difference . 5
7 Data analysis . 6
7.1 General . 6
7.2 Image quality parameter for data analysis . 6
7.3 Environmental conditions . 6
7.4 Estimation of time to reach certain change . 7
8 Reporting . 7
Annex A (informative) Display window type and lighting design . 8
Annex B (informative) Example of test results.10
Bibliography .14
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ISO/TS 21139-21:2019(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 on 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 the following
URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 42, Photography.
A list of all parts in the ISO 21139 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.
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ISO/TS 21139-21:2019(E)

Introduction
In commercial application of colour prints, displaying the prints under ambient light or artificial
illumination is one of the typical use cases. These prints may fade or otherwise change in appearance
due to various environmental stresses, such as light, heat, humidity, pollutant gas, or biological
weathering, and the combination of these factors. One of the most critical degradations is light fading
caused by bright light which includes some UV components. A typical example of such a case is where
prints are displayed in a display window (see Annex A) and are illuminated with bright light, especially
daylight through window glass.
A test method for light stability of prints by simulating daylight through window glass directly falling
on a print displayed in a window is described in of ISO 18937. The test method described in ISO 18937
has broader application (for example covers a broad range of temperatures) than is required for
this document and so requires some modification. A test method for ozone stability is described in
ISO 18941.
In addition, ISO 18937 and ISO 18941 focus on test method itself, and do not cover translation of test
results into performance in specific use profile which is one of the aims of this document.
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TECHNICAL SPECIFICATION ISO/TS 21139-21:2019(E)
Permanence and durability of commercial prints —
Part 21:
In-window display — Light and ozone stability
1 Scope
This document describes the test method for light stability and ozone stability for commercial prints,
which are displayed in indoor bright places in or near to windows, especially in display windows with
air conditioning.
This document also provides guidelines for data analysis.
This document is applicable to the various product classes of “commercial prints” that, following the
terminology of ISO/TR 19300, include commercial production prints (flyers, brochures), transactional
and stationary prints, signage, newspapers and periodical prints, book printing as well as packaging
printing. These commercial prints often contain combinations of text, pictorial images and/or artwork.
Prints for non-commercial use, including prints used and displayed in consumer home environments
and prints exhibited or stored in museum context, are outside the scope of this document.
This document is applicable to both analogue and digitally printed matter. Methods and principles
apply to both, colour and monochrome prints.
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 12647-7, Graphic technology — Process control for the production of halftone colour separations, proof
and production prints — Part 7: Proofing processes working directly from digital data
ISO 13655, Graphic technology — Spectral measurement and colorimetric computation for graphic
arts images
1)
ISO 18937:— , Imaging materials — Photographic reflection prints — Methods for measuring indoor light
stability
ISO 18941:2017, Imaging materials — Colour reflection prints — Test method for ozone gas fading stability
ISO/TS 21139-1, Permanence and durability of commercial prints — Definition of use cases and guiding
principles for specifications
3 Terms and definitions
No terms and definitions are listed in this document.
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/
1)  Under preparation. Stage at the moment of publication ISO/DIS 18937:2019.
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ISO/TS 21139-21:2019(E)

4 Use profile
4.1 General
This document describes a test method for prints that are displayed in display windows, where the
primary stress factors are exposure to daylight through window glass and exposure to ozone. The
effects of light and ozone are assessed separately, instead of combined, in this document.
NOTE Heat, humidity and other pollutant gases also can be stress factors, however this document focuses on
light stability and ozone stability. Heat can have to be considered for long time display in windows, where print is
exposed to direct sunlight.
The use profile of commercial prints in general is described in ISO/TS 21139-1. This document
specifically describes test methods for in-window display with daylight through window glass (see
display use profile A1 of Table 3 in ISO/TS 21139-1).
4.2 Environmental light condition
To determine the cumulative light exposure which is most appropriate for their intended purpose,
users should make an estimate of the typical amount of light exposure anticipated for their application.
The light level depends on geographic location, time of year, window direction and shading factors.
Guidelines are provided in ISO/TS 21139-1.
Users should identify a suitable reference display condition that is likely to be used to display prints. In
such cases, the actual light exposure can be measured for a sufficiently long period. These calculations will
provide a light exposure estimate for this use profile and so may be used to determine the likely fading.
4.3 Environmental ozone condition
To determine the cumulative ozone exposure which is most representative for their intended purpose,
users should make an estimate of the typical amount of ozone exposure anticipated for the duration of
display. The ozone level depends on ventilation of outdoor air, deactivation factors of the room, such as
room size, materials of the wall, ventilation filter, and the weather condition, especially solar radiation.
[9]
For measurement of ozone level, passive samplers (filter badges) can be used .
The indoor ozone level may also be estimated using the ratio of the indoor to outdoor level. This ratio
is calculated by measuring the indoor level for a short period of time and using published measurement
data from a nearby air quality station for this same period. The indoor ozone level may be estimated
[10][11]
from the published outdoor measurement data over a longer period of time using this ratio .
NOTE In most cases, the ratio of indoor to outdoor ozone is more stable compared to the fluctuation of
[10][11]
outdoor ozone level itself .
Users should identify a suitable reference display condition that is likely to be used to display prints. In
such cases, the actual ozone exposure can be measured for a sufficiently long period. These calculations
will provide an ozone exposure estimate for this use profile and so may be used to determine the
likely fading.
5 Test method
5.1 General
The sample specimens shall be exposed to controlled light or ozone gas for a certain duration. The
change from the initial state shall be measured.
The duration of the exposure is determined based on the total anticipated exposure identified in the
use profile.
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ISO/TS 21139-21:2019(E)

5.2 Sample preparation
5.2.1 Outline
Sample specimens shall be prepared with the specific procedures, which correspond to the actual prints
to be evaluated. The printing equipment, the driver setting, the media, finishing shall be recorded.
5.2.2 Test target
The test target described in ISO 12647-7 (Control strip) shall be used. Other test patterns or natural
picture images can also be used depending on the purpose of the test.
5.2.3 Storage conditions between printing and light or ozone exposure test
The storage conditions for the period between printing and the start of the light exposure test and
between the end of aging exposure and the start of the data measurement shall be controlled when
the test results can be affected by the condition, ensuring that the ambient environment (temperature,
relative humidity and air flow around the stored prints) remains within the permitted levels. In any
event, the time between printing and the start of the light exposure test shall be less than two months.
5.2.4 Reference samples
Extra specimens may be prepared for each sample for use as reference samples. When this is done,
the extra specimens shall be sealed in an opaque or dark enclosure and stored at cold place with the
temperature of no higher than 20 °C, so that they can either be measured with the exposed sample
specimens simultaneously or can be assessed visually by comparing the exposed sample specimen with
the unexposed sample specimen side-by-side.
5.2.5 Backing of the specimens
The sample specimens are usually backed. Suitable backing materials include non-reactive and non-
yellowing white material such as 100 % cotton cellulose mount board (100 % 'rag' board) or metal
(white-painted aluminium or stainless steel plate).
NOTE 1 “Backing” refers to an extra rigid and stable sheet of material, to which print is mounted, and backing
also can be a direct printing on such backing material (rag board/coated metal composite sheet).
NOTE 2 The type of backing material used can influence the sample temperature. It is recommended to use a
backing that most closely represents use case conditions.
5.3 Light exposure
5.3.1 Outline
For the light source, xenon arc light filtered with standard window glass filter is used to simulate
daylight through window glass.
Xenon arc lamp equipment that can achieve the test conditions stipulated in this sub-clause shall be used.
Temperature and humidity control equipment shall be used to attain the sample temperatures and the
air relative humidity stipulated in this document.
5.3.2 Spectral power distribution
The spectral power distribution (SPD) stipulated in ISO 18937:—, 7.2, shall be used. This SPD can be
achieved using light from a xenon arc lamp filtered wi
...