SIST EN ISO 16474-1:2014

SLOVENSKI STANDARD
01-februar-2014
1DGRPHãþD
SIST EN ISO 11341:2005
SIST EN ISO 11507:2007
Barve in laki - Metode izpostavljanja laboratorijskim virom svetlobe - 1. del:
Splošna navodila (ISO 16474-1:2013)
Paints and varnishes - Methods of exposure to laboratory light sources - Part 1: General
guidance (ISO 16474-1:2013)
Beschichtungsstoffe - Künstliches Bestrahlen oder Bewittern in Geräten - Teil 1:
Allgemeine Anleitung (ISO 16474-1:2013)
Peintures et vernis - Méthodes d'exposition à des sources lumineuses de laboratoire -
Partie 1: Lignes directrices générales (ISO 16474-1:2013)
Ta slovenski standard je istoveten z: EN ISO 16474-1:2013
ICS:
87.040 Barve in laki Paints and varnishes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 16474-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2013
ICS 87.040 Supersedes EN ISO 11341:2004, EN ISO 11507:2007
English Version
Paints and varnishes - Methods of exposure to laboratory light
sources - Part 1: General guidance (ISO 16474-1:2013)
Peintures et vernis - Méthodes d'exposition à des sources Beschichtungsstoffe - Künstliches Bestrahlen oder
lumineuses de laboratoire - Partie 1: Lignes directrices Bewittern in Geräten - Teil 1: Allgemeine Anleitung (ISO
générales (ISO 16474-1:2013) 16474-1:2013)
This European Standard was approved by CEN on 26 October 2013.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United
Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2013 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 16474-1:2013 E
worldwide for CEN national Members.

Contents Page
Foreword .3

Foreword
This document (EN ISO 16474-1:2013) has been prepared by Technical Committee ISO/TC 35 "Paints and
varnishes" in collaboration with Technical Committee CEN/TC 139 “Paints and varnishes” the secretariat of
which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by May 2014, and conflicting national standards shall be withdrawn at the
latest by May 2014.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 11341:2004, EN ISO 11507:2007.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech
Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,
Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.
Endorsement notice
The text of ISO 16474-1:2013 has been approved by CEN as EN ISO 16474-1:2013 without any modification.
INTERNATIONAL ISO
STANDARD 16474-1
First edition
2013-11-15
Paints and varnishes — Methods of
exposure to laboratory light sources —
Part 1:
General guidance
Peintures et vernis — Méthodes d’exposition à des sources lumineuses
de laboratoire —
Partie 1: Lignes directrices générales
Reference number
ISO 16474-1:2013(E)
©
ISO 2013
ISO 16474-1:2013(E)
© ISO 2013
All rights reserved. Unless otherwise specified, 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
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2013 – All rights reserved

ISO 16474-1:2013(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
4.1 General . 2
4.2 Significance . 2
4.3 Use of accelerated tests with laboratory light sources . 4
5 Requirements for laboratory exposure devices . 4
5.1 Irradiance . 4
5.2 Temperature . 6
5.3 Humidity and wetting . 8
5.4 Other requirements for the exposure device . 9
6 Test specimens — Preparation, replicates, storage and conditioning .9
6.1 Handling of test specimens . 9
6.2 Form, shape, preparation . 9
6.3 Number of test specimens .10
6.4 Storage and conditioning .10
7 Test conditions and procedure .11
7.1 Set points for exposure conditions .11
7.2 Property measurements on test specimens .11
8 Periods of exposure and evaluation of test results .12
8.1 General .12
8.2 Sampling .12
8.3 Determination of changes in properties after exposure .12
8.4 Use of control materials .12
8.5 Use of results in specifications .12
9 Test report .13
Annex A (informative) Procedure for measuring the irradiance uniformity in the specimen
exposure area .15
Annex B (informative) Factors that decrease the degree of correlation between artificial
accelerated weathering or artificial accelerated irradiation exposures and actual-
use exposures .18
Annex C (informative) Solar spectral irradiance standard .21
Bibliography .22
ISO 16474-1:2013(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. 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. 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 meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT) see the following URL: Foreword - Supplementary information
The committee responsible for this document is ISO/TC 35, Paints and varnishes, Subcommittee SC 9,
General test methods for paints and varnishes.
This first edition of ISO 16474-1, together with ISO 16474-2, cancels and replaces ISO 11341:2004, which
has been technically revised. This first edition of ISO 16474-1, together with ISO 16474-3, cancels and
replaces ISO 11507:2007, which has been technically revised.
ISO 16474 consists of the following parts, under the general title Paints and varnishes — Methods of
exposure to laboratory light sources:
— Part 1: General guidance
— Part 2: Xenon-arc lamps
— Part 3: Fluorescent UV lamps
— Part 4: Open-flame carbon-arc lamps
iv © ISO 2013 – All rights reserved

ISO 16474-1:2013(E)
Introduction
Coatings from paints, varnishes and similar materials are often used outdoors or in indoor locations
where they are exposed to solar radiation or to solar radiation behind glass for long periods. It is therefore
very important to determine the effects of solar radiation, heat, moisture and other climatic stresses on
the colour and other properties of polymers. Outdoor exposures to solar radiation and to solar radiation
[9]
filtered by window glass are described in ISO 2810 . However, it is often necessary to determine more
rapidly the effects of light, heat and moisture on the physical, chemical and optical properties of coatings
with artificial accelerated weathering or artificial accelerated irradiation exposures that use specific
laboratory light sources. Exposures in these laboratory devices are conducted under more controlled
conditions than found in natural environments and are intended to accelerate polymer degradation
and product failures. Relating results from accelerated weathering or artificial accelerated irradiation
exposures to those obtained in actual-use conditions is difficult because of variability in both types of
exposure and because laboratory tests often do not reproduce all the exposure stresses experienced
by coatings exposed in actual-use conditions. In addition, the increase in rate of degradation by the
accelerated test compared with natural exposure conditions varies with the type of material and its
formulation. No single laboratory exposure test can be specified as a total simulation of actual-use
exposures. The relative durability of materials in actual-use exposures can be very different depending
on the location of the exposure because of differences in solar radiation, time of wetness, temperature,
pollutants and other factors. Therefore, even if results from specific accelerated weathering or artificial
accelerated irradiation exposures are found to be useful for comparing the relative durability of
materials exposed in a particular outdoor location or in particular actual-use conditions, it cannot
be assumed that they will be useful for determining the relative durability of materials exposed in a
different outdoor location or in different actual-use conditions.
INTERNATIONAL STANDARD ISO 16474-1:2013(E)
Paints and varnishes — Methods of exposure to laboratory
light sources —
Part 1:
General guidance
1 Scope
1.1 This part of ISO 16474 provides information and general guidance relevant to the selection and
operation of the methods of exposure described in detail in subsequent parts. It also describes general
performance requirements for devices used for exposing paints and varnishes to laboratory light sources.
Information about such performance requirements is provided for producers of artificial accelerated
weathering or artificial accelerated irradiation devices.
1.2 This part of ISO 16474 also provides information on the interpretation of data from artificial
accelerated weathering or artificial accelerated irradiation exposures.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 1513, Paints and varnishes — Examination and preparation of test samples
ISO 1514, Paints and varnishes — Standard panels for testing
ISO 2808, Paints and varnishes — Determination of film thickness
ISO 3270, Paints and varnishes and their raw materials — Temperatures and humidities for conditioning
and testing
ISO 4618, Paints and varnishes — Terms and definitions
ISO 9370, Plastics — Instrumental determination of radiant exposure in weathering tests — General
guidance and basic test method
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
ISO 16474-2, Paints and varnishes — Methods of exposure to laboratory light sources — Part 2: Xenon-arc lamps
ISO 16474-3, Paints and varnishes — Methods of exposure to laboratory light sources — Part 3:
Fluorescent UV lamps
ISO 16474-4, Paints and varnishes — Methods of exposure to laboratory light sources — Part 4: Open-flame
carbon-arc lamps
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4618 and the following apply.
ISO 16474-1:2013(E)
3.1
artificial accelerated irradiation
exposure of a material to a laboratory radiation source intended to simulate window-glass-filtered solar
radiation or radiation from interior lighting sources and where specimens are subjected to relatively
small changes in temperature and relative humidity in an attempt to produce more rapidly the same
changes that occur when the material is used in an indoor environment
Note 1 to entry: These exposures are commonly referred to as fading or light fastness tests.
3.2
artificial accelerated weathering
exposure of a material in a laboratory weathering device to conditions which may be cyclic and intensified
compared with those encountered in outdoor or in-service exposure
Note 1 to entry: This involves a laboratory radiation source, heat and moisture (in the form of relative humidity
and/or water spray, condensation or immersion) in an attempt to produce more rapidly the same changes that
occur in long-term outdoor exposure.
Note 2 to entry: The device may include means for control and/or monitoring of the light source and other
weathering parameters. It may also include exposure to special conditions, such as acid spray to simulate the
effect of industrial gases.
3.3
control material
material which is of similar composition and construction to the test material and which is exposed at
the same time for comparison with the test material
Note 1 to entry: An example of the use of a control material would be when a formulation different from one currently
being used is being evaluated. In that case, the control would be the coating made with the original formulation.
3.4
file specimen
portion of the material to be tested which is stored under conditions in which it is stable and which is
used for comparison between the exposed and unexposed states
3.5
reference material
material of known performance
3.6
reference specimen
portion of the reference material that is to be exposed
4 Principle
4.1 General
Specimens of the samples to be tested are exposed to laboratory light sources under controlled
environmental conditions. The methods described include the requirements which have to be met for
the measurement of the irradiance and radiant exposure in the plane of the specimen, the temperature
of specified white and black sensors, the chamber air temperature and the relative humidity.
4.2 Significance
4.2.1 When conducting exposures in devices that use laboratory light sources, it is important to
consider how well the accelerated-test conditions simulate the actual-use environment for the paint or
varnish being tested. In addition, it is essential to consider the effects of variability in both the accelerated
test and actual exposures when setting up exposure experiments and when interpreting the results from
artificial accelerated weathering or artificial accelerated irradiation exposures.
2 © ISO 2013 – All rights reserved

ISO 16474-1:2013(E)
4.2.2 No laboratory exposure test can be specified as a total simulation of actual-use conditions. Results
obtained from artificial accelerated weathering or artificial accelerated irradiation exposures can be
considered as representative of actual-use exposures only when the degree of rank correlation has been
established for the specific materials being tested and when the type and mechanism of degradation are
the same. The relative durability of materials in actual-use conditions can be very different in different
locations because of differences in solar radiation, time of wetness, relative humidity, temperature,
pollutants and other factors. Therefore, even if results from a specific exposure test conducted in
accordance with any of the parts of this International Standard are found to be useful for comparing the
relative durability of materials exposed in a particular environment, it cannot be assumed that they will
be useful for determining the relative durability of the same materials in a different environment.
4.2.3 Even though it is very tempting, it is invalid to assign to all materials a “general acceleration factor”
relating “x” hours or megajoules of radiant exposure in an artificial accelerated weathering or artificial
accelerated irradiation exposure to “y” months or years of actual exposure. Such acceleration factors are
invalid for the following reasons:
a) acceleration factors are material-dependent and can be significantly different for each material and
for different formulations of the same material;
b) variability in the rate of degradation in both actual-use and artificial accelerated weathering
or artificial accelerated irradiation exposures can have a significant effect on the calculated
acceleration factor;
c) acceleration factors calculated based on the ratio of irradiance between a laboratory light source and
solar radiation (even when identical pass-bands are used) do not take into consideration the effects
of temperature, moisture and differences in spectral power distribution between the laboratory
light source and solar radiation.
NOTE Acceleration factors determined for a specific formulation of a material are valid, but only if they are
based on data from a sufficient number of separate outdoor or indoor environmental tests and artificial accelerated
weathering or artificial accelerated irradiation exposures so that results used to relate times to failure in each
exposure can be analysed using statistical methods. An example of a statistical analysis using multiple laboratory
[1]
and actual exposures to calculate an acceleration factor is described by J.A. Simms .
4.2.4 There are a number of factors that might decrease the degree of correlation between accelerated
tests using laboratory light sources and exterior exposures (more specific information on how each factor
can alter the stability ranking of materials is given in Annex B):
a) differences in the spectral irradiance of the laboratory light source and solar radiation;
b) irradiance levels higher than those experienced in actual-use conditions;
c) exposure cycles that use continuous exposure to light from a laboratory light source without any
dark periods;
d) specimen temperatures higher than those in actual conditions;
e) exposure conditions that produce unrealistic temperature differences between light- and dark-
coloured specimens;
f) exposure conditions that produce very frequent cycling between high and low specimen
temperatures, or that produce unrealistic thermal shock;
g) unrealistic levels of moisture in the accelerated test compared to actual-use conditions;
h) the absence of biological agents, pollutants or acidic precipitation or condensation.
ISO 16474-1:2013(E)
4.3 Use of accelerated tests with laboratory light sources
4.3.1 Results from artificial accelerated weathering or artificial accelerated irradiation exposures
conducted in accordance with any of the parts of this International Standard are best used to compare the
relative performance of materials. Comparisons between materials can only be made when the materials
are tested at the same time in the same exposure device. Results can be expressed by comparing the
exposure time or radiant exposure necessary to reduce the level of a characteristic property to some
specified level. A common application of this is a test conducted to establish that the level of quality of
different batches does not vary from that of a control of known performance.
4.3.1.1 It is strongly recommended that at least one control be exposed with each test for the purpose
of comparing the performance of the test materials to that of the control. The control material should be
of similar composition and construction and be chosen so that its failure modes are the same as that of
the material being tested. It is preferable to use two controls, one with relatively good durability and one
with relatively poor durability.
4.3.1.2 Sufficient replicates of each control and each test material being evaluated are necessary in
order to allow statistical evaluation of the results. Unless otherwise specified, use a minimum of three
replicates for all test and control materials. When material properties are measured using destructive
tests, a separate set of specimens is needed for each exposure period.
4.3.2 In some specification tests, test materials are exposed at the same time as a weathering reference
material (e.g. blue wool test fabric). The property or properties of the test material are measured after
a defined property of the reference material reaches a specified level. If the reference material differs in
composition from the test material, it might not be sensitive to exposure stresses that produce failure
in the test material or it might be very sensitive to an exposure stress that has very little effect on the
test material. The variability in results for the reference material might be very different from that for
the test material. All these differences between the reference material and the test material can produce
misleading results when the reference material is used as a control or to determine the length of the
exposure period.
NOTE 1 Definitions of control and reference materials that are appropriate to weathering tests are given in Clause 3.
NOTE 2 Weathering reference materials can also be used to monitor the consistency of the operating conditions
in an exposure test. Information about the selection and characterization of reference materials used for this
[2] [3]
purpose can be found in ASTM G 156 . ISO/TR 19032 describes a procedure which uses the change in the
carbonyl index of a specific polyethylene weathering reference material to monitor conditions in both natural
weathering and artificial accelerated weathering exposures.
4.3.3 In some specification tests, properties of test specimens are evaluated after a specific exposure
time or radiant exposure using a test cycle with a prescribed set of conditions. Results from any accelerated
exposure test conducted in accordance with any of the parts of this International Standard should not be
used to make a “pass/fail” decision for materials, based on the level of a specific property after a specific
exposure time or radiant exposure, unless the combined reproducibility of the effects of a particular
exposure cycle and property measurement method has been established.
5 Requirements for laboratory exposure devices
Laboratory exposure devices shall be equipped with facilities to provide specimens with irradiance
(5.1), temperature (5.2), humidity and wetting (5.3).
5.1 Irradiance
5.1.1 Laboratory light sources are used to provide irradiance for the test specimens. In ISO 16474-2 a
xenon-arc lamp is used to provide the irradiance for the specimens, in ISO 16474-3 a fluorescent UV lamp,
and in ISO 16474-4 an open-flame carbon-arc lamp.
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ISO 16474-1:2013(E)
5.1.2 The exposure device shall provide for placement of specimens and any designated sensing devices
in positions that allow uniform irradiance from the light source.
NOTE The spectral irradiance produced in an artificial accelerated weathering device is very important.
Ideally, the relative spectral irradiance produced by the device should be a very close match to that of solar
radiation, especially in the short-wavelength UV region. Annex C provides information about a benchmark solar
spectrum that can be used for comparing the spectral irradiance produced in the artificial accelerated exposure
to that for solar radiation. Subsequent parts of this International Standard contain specific requirements for the
relative spectral irradiance produced in the devices described in those parts.
5.1.3 Exposure devices shall be designed such that the irradiance at any location in the area used for
specimen exposures is at least 70 % of the maximum irradiance measured in this area. Procedures for
measuring irradiance uniformity by the device manufacturers are given in Annex A.
NOTE The irradiance uniformity in exposure devices depends on several factors, such as deposits that
can develop on the optical system and chamber walls. In addition, irradiance uniformity can be affected by the
type of specimen and the number of specimens being exposed. The irradiance uniformity as guaranteed by the
manufacturer is valid for new equipment and well-defined measuring conditions.
5.1.4 Depending on the specific sensitivity of the material periodic repositioning of the specimens is
good practice in order to be sure that the variability in exposure stresses experienced during the exposure
period is kept to the minimum. If the irradiance at any position in the area used for specimen exposure
is between 70 % and 90 % of the maximum irradiance, specimens shall be periodically repositioned to
reduce the variability in radiant exposure.
NOTE Random placement of replicate specimens is also good practice to reduce the effect of any variability
in the conditions within the exposure area.
5.1.5 Follow the device manufacturer’s instructions for lamp and filter replacement and for pre-ageing
of lamps and/or filters.
5.1.6 A radiometer that complies with the requirements outlined in ISO 9370 may be used to measure
the irradiance E or spectral irradiance E and the radiant exposure H or spectral radiant exposure H in
λ λ
the plane of the specimen surface.
5.1.6.1 If used, the radiometer shall be mounted so that it receives the same radiation as the specimen
surface. If it is not positioned in the specimen plane, it shall have a sufficiently wide field of view and be
calibrated for irradiance at the specimen distance.
5.1.6.2 The field radiometer shall be calibrated in the emission region of the light source used with
a reference radiometer. The radiometer shall be calibrated using a light source filter combination of
the same type that will be used for testing or an appropriate spectral mismatch factor has been taken
into account. The calibration shall be checked in accordance with the radiation measuring instrument
manufacturer’s instructions.
For fluorescent UV lamps, it has been shown that the field radiometers have to be calibrated with lamps
that have a spectral power distribution which is identical to that of the lamps that will be used for testing.
NOTE Refer to ISO 9370 for definitions of field and reference radiometers.
5.1.6.3 When measured, the irradiance in the wavelength range agreed upon by all interested parties
shall be reported. Some types of device provide for measuring irradiance in a specific wavelength range
(e.g. 300 nm to 400 nm or 300 nm to 800 nm) or in a narrow pass-band that is centred around a single
wavelength (e.g. 340 nm).
ISO 16474-1:2013(E)
5.2 Temperature
5.2.1 The surface temperature of exposed materials depends primarily on the amount of radiation
absorbed, the emissivity of the specimen, the amount of thermal conduction within the specimen and
the amount of heat transmission between the specimen and the air or between the specimen and the
specimen holder. Since it is not practical to monitor the surface temperature of individual test specimens,
a specified black surface sensor is used to measure and control the temperature within the exposure
chamber. The black surface temperature sensor shall be mounted within the specimen exposure area so
that it receives the same radiation and experiences the same cooling conditions as a flat test panel surface.
5.2.2 Two types of black surface temperature sensor may be used: a black-standard thermometer (BST)
and a black-panel thermometer (BPT).
5.2.2.1 Black-standard thermometers, consisting of a plane (flat) stainless-steel plate with a thickness
of 0,5 mm to 1,2 mm. A typical length and width is about 70 mm by 40 mm. The surface of this plate facing
the light source shall be coated with a black layer which has good resistance to ageing. The coated black
plate shall reflect no more than 10 % of all incident flux up to 2 500 nm. A thermally sensitive element
such as a platinum resistance sensor shall be attached to the centre of the plate, in good thermal contact
with the plate, on the side opposite the radiation source. This side of the metal plate shall be attached to a
5 mm thick baseplate made of unfilled poly(vinylidene fluoride) fluoride (PVDF). A small space sufficient
to hold the platinum resistance sensor shall be machined in the PVDF baseplate. The distance between
the sensor and this recess in the PVDF plate shall be about 1 mm. The length and width of the PVDF
plate shall be sufficient so that no metal-to-metal thermal contact exists between the black-coated metal
plate and the mounting holder into which it is fitted. The metal mounts of the holder of the insulated
black panel shall be at least 4 mm from the edges of the metal plate. Black-standard thermometers which
differ in construction from that specified above are permitted as long as the temperature indicated by
the alternative construction is within ± 1,0 °C of that of the specified construction at all steady-state
temperature and irradiance settings the exposure device is capable of attaining. In addition, the time
needed for an alternative black-standard thermometer to reach the steady-state shall be within 10 % of
the time needed for the specified black-standard thermometer to reach the steady-state.
NOTE Black-standard thermometers are sometimes referred to as insulated black-panel thermometers.
5.2.2.2 Black-panel thermometers, consisting of a plane (flat) metal plate that is resistant to corrosion.
Typical dimensions are about 150 mm long, 70 mm wide and 1 mm thick. The surface of this plate that
faces the light source shall be coated with a black layer which has good resistance to ageing. The coated
black plate shall reflect no more than 10 % of all incident flux up to 2 500 nm. A thermally sensitive element
shall be firmly attached to the centre of the exposed surface. This thermally sensitive element may be a
black-coated stem-type bimetallic dial sensor, a resistance-based sensor, a thermistor or a thermocouple.
The back side of the metal panel shall be open to the atmosphere.
NOTE Black-panel thermometers are sometimes referred to as uninsulated black-panel thermometers.
5.2.2.3 Unless otherwise specified, temperatures shall be measured using either of the thermometer
designs described above. If other means are used to measure the temperature of black or white panels,
the exact construction of the black or white panel shall be included in the test report.
5.2.3 The temperature indicated by the black-panel or black-standard thermometer depends on the
irradiance produced by the laboratory light source and the temperature and speed of the air moving in the
exposure chamber. Black-panel temperatures generally correspond to those for dark coatings on metal
panels without thermal insulation on the rear side. Black-standard thermometer temperatures generally
correspond to those for the exposed surface of dark samples with poor thermal conductivity. At conditions
used in typical exposures, the temperature indicated by a black-standard thermometer will be 3 °C to 12 °C
higher than that indicated by a black-panel thermometer. The actual difference between a black-panel
temperature and a temperature measured with a black-standard thermometer should, however, preferably
be determined for each exposure condition. Because black-standard thermometers are insulated, their
response time for temperature changes is slightly slower than for a black-panel thermometer.
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ISO 16474-1:2013(E)
5.2.4 At low irradiance levels, the difference between the temperature indicated by a black-panel or
black-standard thermometer and the real specimen temperature can be small. When light sources that
emit very little infrared radiation are used, there will generally be only very small differences in the
temperatures indicated by the two types of black panel or between light- and dark-coloured specimens.
5.2.5 In order to evaluate the range of surface temperatures of the exposed specimens and to better
control the irradiance or the conditions in the exposure chamber, the use of a white-panel or white-standard
thermometer, in addition to the black-panel or black-standard thermometer, is recommended. The white-
panel or white-standard thermometer shall be constructed in the same way as the corresponding black-
panel or black-standard thermometer, except for the use of a white coating with a good resistance to
ageing. The reflectance of the white coating shall be at least 60 % between 450 nm and 800 nm and at
least 30 % between 800 nm and 1 500 nm.
5.2.6 Manufacturers of exposure devices shall ensure that devices designed to meet the requirements
of this part of ISO 16474 are able to meet the following requirements for control of the temperature of
the black or white temperature sensor at the position where it is intended to operate (see Table 1). These
requirements apply to equilibrium conditions.
Table 1 — Requirements for set-point temperature of the black or white temperature sensor at
the position where it is intended to operate
Allowable deviation of the sensor temperature at
Set-point temperature
the position in which sensor operates
≤ 70 °C ±3 °C
≥ 70 °C ±4 °C
5.2.7 Manufacturers of exposure devices shall ensure that devices designed to meet the requirements
of this part of ISO 16474 are able to meet the following requirements for control of the temperature of a
black or white temperature sensor at any position within the allowed exposure area (see Table 2). These
requirements apply to equilibrium conditions.
Table 2 — Requirements for set-point temperature of the black or white temperature sensor at
any position within the allowed exposure area
Allowable deviation of the sensor temperature
Set-point temperature
when sensor placed anywhere in the exposure area
≤ 70 °C ±5 °C
≥ 70 °C ±7 °C
NOTE For some materials, differences in the degradation rate can occur between devices operating within the
allowable temperature ranges. Periodic repositioning of specimens or random positioning of replicate specimens
during exposure will reduce the variability caused by differences in temperature within the exposure area.
5.2.8 The test report shall indicate whether a black-standard or black-panel thermometer was used
and whether a white-standard or white panel thermometer was used.
NOTE Different temperatures may be indicated by a single type of black-standard or black-panel thermometer,
depending on the specific design of the device supplied by different manufacturers.
5.2.9 If the exposure chamber air temperature is measured, the temperature-sensing element shall be
shielded from the light source and water spray. The chamber air temperature measured at this position
might not be the same as the chamber air temperature near the surface of the exposed specimens.
Manufacturers of devices that control chamber air temperature shall ensure that their equipment is able
to maintain the measured chamber air temperature within ± 3 °C of the set point under equilibrium
conditions for set points up to 70 °C and within ± 4 °C of the set point for set points greater than 70 °C.
ISO 16474-1:2013(E)
5.2.10 Calibrate the temperature sensor used to measure the chamber air temperature in accordance
with the sensor manufacturer’s instructions at least annually.
5.3 Humidity and wetting
5.3.1 Moisture
The presence of moisture on the exposed face of the specimen, particularly long wet periods and the
cyclic change between wet and dry periods, might have a significant effect in accelerated laboratory
exposure tests. An
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