ISO 18937-2:2023

INTERNATIONAL ISO
STANDARD 18937‐2
First edition
2023-06
Imaging materials — Methods for
measuring indoor light stability of
photographic prints —
Part 2:
Xenon‐arc lamp exposure
Matériaux pour l'image — Méthodes de mesure de la stabilité de la
lumière en intérieur des épreuves photographiques —
Partie 2: Exposition à une lampe à arc au xénon
Reference number
ISO 18937-2:2023(E)
© ISO 2023

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ISO 18937‐2:2023(E)
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Published in Switzerland
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ISO 18937‐2:2023(E)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Apparatus . 2
6 Test specimens . 3
7 Exposure conditions .3
7.1 General . 3
7.2 General indoor display . 4
7.2.1 Application . 4
7.2.2 Filters to simulate general indoor display conditions . 4
7.2.3 Radiation intensity, temperature, and humidity . 4
7.3 Simulated in-window display . 5
7.3.1 Application . 5
7.3.2 Filtered xenon arc configuration to simulate in-window display conditions . 5
7.3.3 Radiation intensity, temperature and humidity . 6
8 Test result measurement and report . 6
Annex A (informative) Relative spectral transmittance of filters . 7
Annex B (informative) Sample temperature measurements based on different parameters .9
Bibliography .13
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ISO 18937‐2:2023(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 42, Photography. This first edition of
ISO 18937-2 cancels and replaces the second edition of ISO 18937:2020, which has been technically
revised.
The main changes are as follows:
— This revision of the existing ISO 18937 separates the International Standard into three separate
parts in a similar way to two other artificial exposure testing series, ISO 4892 (Plastics, in TC 61),
and ISO 16474 (Paints and varnishes, in TC 35).
A list of all parts in the ISO 18937 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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INTERNATIONAL STANDARD ISO 18937‐2:2023(E)
Imaging materials — Methods for measuring indoor light
stability of photographic prints —
Part 2:
Xenon‐arc lamp exposure
1 Scope
This document describes test equipment and procedures for measuring the light stability of
photographic prints when subjected to a filtered xenon-arc light source at specified levels of illuminance
(irradiance), temperature and relative humidity. It is applicable to both colour and monochrome
reflection prints, transparent films, or translucent films. It is also applicable to photographic prints in
general, photobooks, or prints for backlit displays.
General indoor display conditions described herein are intended to simulate common use conditions
found in houses, apartments and other dwelling places where indirect lighting due to filtering (through
window glass) and shading is often the principal illumination causing displayed photographs to fade.
Simulated in-window display conditions are intended to simulate terrestrial daylight transmitted
through standard architectural window glass (double glazing). A typical example of such display can
be found when images are displayed in store windows, facing toward the outdoors, so that they can be
[5][6]
viewed by people outside of the store .
NOTE It is recognized that in some instances, physical degradation such as support embrittlement, image
layer cracking, or delamination of an image layer from its support, rather than the stability of the image itself,
will determine the useful life of a print material.
General guidance is given in ISO 18937-1.
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 9370, Plastics — Instrumental determination of radiant exposure in weathering tests — General
guidance and basic test method
ISO 18913, Imaging materials — Permanence — Vocabulary
ISO 18937-1, Imaging materials — Photographic reflection prints — Methods for measuring indoor light
stability — Part 1: General guidance and requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18913 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/
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ISO 18937‐2:2023(E)
4 Principle
A xenon arc lamp, fitted with filters, is used to simulate the relative spectral irradiance of various end-
use conditions to simulate standardized indoor lighting conditions by their relative spectral irradiance
in the ultraviolet (UV) and visible regions of the spectrum.
Depending on intended user or application cases, specimens are exposed to desired levels of light, heat,
and relative humidity under controlled environmental conditions.
The exposure conditions are varied by selection of
a) the light filter(s),
b) the irradiance or illuminance level,
c) the temperature during exposure to light,
d) the relative humidity in the chamber during light and dark exposures,
e) the relative duration of the light and dark periods.
The procedure includes measurements of the irradiance or illuminance and radiant exposure in the
plane of the specimens.
5 Apparatus
5.1 Laboratory light source.
5.1.1 General
The light source shall comprise one or more quartz-jacketed xenon-arc lamps which emit radiation from
below 270 nm in the ultraviolet through the visible spectrum and into the infrared. In order to simulate
the end-use conditions, filters shall be used to remove short-wavelength UV radiation.
5.1.2 Optical filters.
Filters are used with the intention of reproducing as closely as possible different end-use lighting
[3][4]
conditions . Special filtering of the xenon-arc lamp is used to achieve two specific lighting conditions
applicable to this method.
The optical filters shall be placed at any position between the light source and the specimens to achieve
the required spectral irradiance conditions. The filters can be placed near the light source or near the
specimens, but the air gap between the specimens and the filter shall allow an unobstructed airflow
between the filter and the specimens.
5.1.3 Irradiance uniformity.
The irradiance at any position in the area used for specimen exposure shall be at least 80 % of the
maximum irradiance. Periodic repositioning of specimens when irradiance uniformity is between 80 %
and 90 % is described in ISO 18937-1.
NOTE For some materials of high sensitivity to irradiance and temperature, periodic repositioning of
specimens is recommended to ensure uniformity of exposures, even when the irradiance uniformity in the
exposure area is within the limits where repositioning would not be required.
5.2 Test chamber.
The design of the test chamber may vary, but it shall be constructed from inert material. The test
chamber shall provide control systems for irradiance, temperature and humidity.
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ISO 18937‐2:2023(E)
The light source(s) shall be located, with respect to the specimens, such that the irradiance (or
illuminance) at the specimen surface conforms with 7.1.
NOTE If the lamp system (one or more lamps) is centrally positioned in the chamber, the effect of any
eccentricity of the lamp(s) on the uniformity of exposure can be reduced by using a rotating rack.
5.3 Radiometer.
Radiometers or illuminance meters used shall conform with the requirements outlined in ISO 18937-1
and ISO 9370.
5.4 Black‐panel thermometer.
The black-panel thermometer shall conform with the requirements for these devices given in
ISO 18937-1.
5.5 Humidity.
The specific end-use conditions describe the required humidity level control. The location of the sensors
used to measure the humidity shall be as specified in ISO 18937-1.
5.6 Specimen holders.
Specimen holders may be constructed in the form of an open frame, leaving the backs of the specimens
exposed, or they may provide a solid backing for the specimens. Transparent or translucent materials
shall always be exposed with an open backing. They shall be made from inert materials that will not
affect the results of the exposure. The backing used may affect the results, especially with respect to
specimen temperature.
5.7 Apparatus to assess changes in properties.
For print materials, measurements of colorimetric or densitometric properties are typically used to
assess property change before and after exposure. Data are commonly reported in graph form, with
exposure level as the x-axis and densitometric or colorimetric change as the y-axis.
5.8 Air quality in the test environment.
Some types of print materials can be highly sensitive to degradation caused by ozone or other airborne
pollutants. See ISO 18937-1 for requirements related to monitoring and reduction of these pollutants.
6 Test specimens
ISO 18937-1 contains information related to the requirements for test specimen creation, replication,
conditioning, handling, and positioning in the exposure area.
7 Exposure conditions
7.1 General
If a reciprocity behaviour test is conducted, lower radiant intensity, e.g. 10 % of nominal condition, shall
be used (details are described in ISO 18937-1:2023, Annex A).
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ISO 18937‐2:2023(E)
7.2 General indoor display
7.2.1 Application
This test is intended to simulate common use conditions found in houses, apartments and other
dwelling pl
...