EN ISO 4892-1:2024

Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance and requirements (ISO 4892-1:2024)

This document provides general guidance and requirements relevant to the selection and operation of the methods of exposure described in detail in subsequent parts of the ISO 4892 series. It also specifies general performance requirements for devices used for exposing plastics to laboratory light sources. Information regarding performance requirements is for producers of artificial accelerated weathering or artificial accelerated irradiation devices.
This document also provides information on the interpretation of data from artificial accelerated weathering or artificial accelerated irradiation exposures. More specific information about methods for determining the change in the properties of plastics after exposure and reporting these results is not part of this document.

Kunststoffe - Künstliches Bestrahlen oder Bewittern in Geräten - Teil 1: Allgemeine Anleitung und Anforderungen (ISO 4892‑1:2024)

Dieses Dokument gibt eine allgemeine Anleitung und Anforderungen für die Auswahl und Durchführung der in den nachfolgenden Teilen der Normenreihe ISO 4892 ausführlich beschriebenen Beanspruchungsverfahren. Es legt auch allgemeine Leistungsanforderungen an Geräte fest, die zur Beanspruchung von Kunststoffen mit Laborstrahlungsquellen angewendet werden, an. Die Informationen über Leistungsanforderungen sind für die Hersteller von Geräten für beschleunigte künstliche Bewitterung oder beschleunigte künstliche Bestrahlung bestimmt.
Dieses Dokument enthält außerdem Informationen zur Auswertung der Daten von Beanspruchungen durch beschleunigte künstliche Bewitterung oder beschleunigte künstliche Bestrahlung. Genauere Informationen über die Verfahren zur Bestimmung der Änderung der Eigenschaften von Kunststoffen nach der Beanspruchung und zur Angabe dieser Ergebnisse im Prüfbericht sind nicht Teil dieses Dokuments.

Plastiques - Méthodes d'exposition à des sources lumineuses de laboratoire - Partie 1:Lignes directrices générales et exigences (ISO 4892-1:2024)

Le présent document fournit un guide général et des exigences pour la sélection et l’application des méthodes d’exposition détaillées dans les autres parties de la série ISO 4892. Il spécifie également les exigences générales de performance des dispositifs utilisés pour exposer les plastiques aux sources lumineuses de laboratoire. Les informations relatives aux exigences de performance sont destinées aux fabricants d’appareillages d’essai de vieillissement accéléré artificiel ou d’irradiation accélérée artificielle.
Le présent document fournit également des informations sur l’interprétation des données issues des essais de vieillissement accéléré artificiel ou d’irradiation accélérée artificielle. Il ne contient pas d'informations plus spécifiques sur les méthodes de détermination des changements de propriétés des plastiques après exposition et de notification de ces résultats.

Polimerni materiali - Metode izpostavljanja laboratorijskim virom svetlobe - 1. del: Splošna navodila (ISO 4892-1:2024)

Ta dokument vsebuje splošna navodila o izbiri in delovanju metod izpostavljanja, ki so podrobno opisane v naslednjih delih skupine standardov ISO 4892. Poleg tega določa splošne zahteve glede zmogljivosti za naprave, ki se uporabljajo za izpostavljanje polimernih materialov laboratorijskim virom svetlobe. Informacije v zvezi z zahtevami glede zmogljivosti so namenjene proizvajalcem naprav za umetno pospešeno vremensko vplivanje ali umetno pospešeno obsevanje.
Ta dokument vsebuje tudi informacije o razlagi podatkov v zvezi z izpostavljenostjo umetnemu pospešenemu vremenskemu vplivanju ali umetnemu pospešenemu obsevanju. Podrobnejše informacije o metodah za ugotavljanje sprememb lastnosti polimernih materialov po izpostavljenosti in poročanju rezultatov niso podane v tem dokumentu.

General Information

• Status: Published
• Publication Date: 22-Oct-2024
• ICS: 83.080.01 - Plastics in general
• Technical Committee: CEN/TC 249 - Plastics
• Drafting Committee: CEN/TC 249 - Plastics
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 23-Oct-2024
• Completion Date: 23-Oct-2024
• Ref Project: SIST EN ISO 4892-1:2024 - Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance (ISO 4892-1:2024)

Relations

• Replaces: EN ISO 4892-1:2016 - Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance (ISO 4892-1:2016)
• Effective Date: 28-Jan-2023

Overview

EN ISO 4892-1:2024 - "Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance and requirements" (ISO 4892-1:2024) is a CEN-adopted ISO standard (October 2024) that provides general guidance and mandatory requirements for selecting and operating laboratory methods that expose plastics to artificial light sources. It sets performance requirements for laboratory accelerated weathering and irradiation devices, explains how to interpret accelerated-exposure data, and updates definitions and calibration expectations from the 2016 edition. It does not prescribe detailed test methods for measuring property changes or reporting results (those are in subsequent parts of the ISO 4892 series).

Key topics and requirements

• Scope & purpose: Guidance for selection, operation and interpretation of artificial accelerated weathering and irradiation tests for plastics.
• Device performance: General performance requirements for exposure devices, including calibration and verification.
• Irradiance: Requirements for irradiance control, calibration and uniformity across specimen exposure areas (Annex A contains measurement procedures).
• Temperature control: Definitions and requirements for measurement methods (black-panel, black-standard, white-panel, white-standard thermometers) and calibration.
• Humidity and wetting: Requirements for controlling moisture and wetting cycles in devices.
• Test specimens: Guidance on specimen form, preparation, number, storage and conditioning.
• Test conditions & procedures: Set points, sampling for intermediate/final evaluation (new subclause 7.3), and measurement considerations during exposures.
• Data interpretation: Guidance on using control materials, exposure periods, and limitations when correlating accelerated tests with real-world exposures (Annex B lists factors that reduce correlation).
• Reporting: Updated requirements for the test report content.
• Normative and informative annexes: Methods for irradiance uniformity, factors affecting correlation with real-use exposures, and solar spectral irradiance standards (Annex C references CIE 241).

Applications and users

This standard is essential for:

• Test laboratories performing accelerated weathering or irradiation tests on plastics.
• Manufacturers of accelerated weathering/irradiation devices (performance and calibration requirements).
• Materials engineers and R&D teams assessing UV, light and climate resistance of plastic materials and formulations.
• Quality and compliance specialists writing specifications that reference accelerated exposure performance.
• Standards committees and researchers comparing lab data with outdoor or actual-use exposures.

Keywords: EN ISO 4892-1:2024, plastics, accelerated weathering, laboratory light sources, irradiance, black-panel thermometer, accelerated irradiation.

Related standards

• ISO 4892 series (other parts with specific exposure methods)
• ISO 877 (outdoor exposures)
• ISO/TR 18486, ISO 23741 (referenced)
• CIE 241 (solar spectral irradiance standards)

Standards Content (Sample)

SLOVENSKI STANDARD
01-december-2024
Polimerni materiali - Metode izpostavljanja laboratorijskim virom svetlobe - 1. del:
Splošna navodila (ISO 4892-1:2024)
Plastics - Methods of exposure to laboratory light sources - Part 1: General guidance
(ISO 4892-1:2024)
Kunststoffe - Künstliches Bestrahlen oder Bewittern in Geräten - Teil 1: Allgemeine
Anleitung (ISO 4892-1:2024)
Plastiques - Méthodes d'exposition à des sources lumineuses de laboratoire - Partie 1:
Lignes directrices générales (ISO 4892-1:2024)
Ta slovenski standard je istoveten z: EN ISO 4892-1:2024
ICS:
83.080.01 Polimerni materiali na Plastics in general
splošno
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 4892-1
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2024
EUROPÄISCHE NORM
ICS 83.080.01 Supersedes EN ISO 4892-1:2016
English Version
Plastics - Methods of exposure to laboratory light sources -
Part 1: General guidance and requirements (ISO 4892-
1:2024)
Plastiques - Méthodes d'exposition à des sources Kunststoffe - Künstliches Bestrahlen oder Bewittern in
lumineuses de laboratoire - Partie 1:Lignes directrices Geräten - Teil 1: Allgemeine Anleitung und
générales et exigences (ISO 4892-1:2024) Anforderungen (ISO 4892-1:2024)
This European Standard was approved by CEN on 17 October 2024.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 4892-1:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 4892-1:2024) has been prepared by Technical Committee ISO/TC 61 "Plastics"
in collaboration with Technical Committee CEN/TC 249 “Plastics” the secretariat of which is held by SIS.
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 April 2025, and conflicting national standards shall be
withdrawn at the latest by April 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 4892-1:2016.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
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, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 4892-1:2024 has been approved by CEN as EN ISO 4892-1:2024 without any
modification.
International
Standard
ISO 4892-1
Fourth edition
Plastics — Methods of exposure to
2024-10
laboratory light sources —
Part 1:
General guidance and requirements
Plastiques — Méthodes d'exposition à des sources lumineuses de
laboratoire —
Partie 1: Lignes directrices générales et exigences
Reference number
ISO 4892-1:2024(en) © ISO 2024

ISO 4892-1:2024(en)
© ISO 2024
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 4892-1:2024(en)
Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 3
4.1 General .3
4.2 Significance . . .3
4.3 Use of accelerated tests with laboratory light sources .5
5 Requirements for laboratory exposure devices . 6
5.1 Irradiance .6
5.2 Temperature .7
5.3 Humidity and wetting .10
5.4 Other requirements for the exposure device .11
6 Test specimens .11
6.1 Form, shape and preparation .11
6.2 Number of test specimens . 12
6.3 Storage and conditioning . 12
7 Test conditions and procedure .13
7.1 Set points for exposure conditions . 13
7.2 Property measurements on test specimens.14
7.3 Sampling for intermediate and final evaluation .14
8 Periods of exposure and evaluation of test results. 14
8.1 General .14
8.2 Use of control materials .14
8.3 Use of results in specifications . 15
9 Test report .15
Annex A (normative) Procedures for measuring the irradiance uniformity in the specimen
exposure area .18
Annex B (informative) Factors that decrease the degree of correlation between artificial
accelerated weathering or artificial accelerated irradiation exposures and actual-use
exposures .21
Annex C (informative) Solar spectral irradiance standards .24
Bibliography .27

iii
ISO 4892-1:2024(en)
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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 61, Plastics, Subcommittee SC 6, Ageing,
chemical and environmental resistance, in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 249, Plastics, in accordance with the Agreement on technical cooperation
between ISO and CEN (Vienna Agreement).
This fourth edition cancels and replaces the third edition (ISO 4892-1:2016), which has been technically
revised.
The main changes are as follows:
— the definition of file specimen (see 3.2) and weathering reference material (see 3.5) have been clarified
and Notes to entry have been added;
— definition and Notes to entry of artificial accelerated weathering (see 3.3) and artificial accelerated
irradiation (see 3.4) have been clarified;
— new terms, definitions and Notes to entry have been added for black-panel thermometer (see 3.7), black-
standard thermometer (see 3.8), white-panel thermometer (see 3.9), and white-standard thermometer
(see 3.10);
— reference to ISO/TR 18486 has been added under 4.2.4;
— calibration requirements have been clarified in 5.1.7, 5.2.8, 5.2.9, 5.3.6;
— requirements regarding black-panel thermometer, black-standard thermometer, white-panel
thermometer, and white-standard thermometer in 5.2 and Table 2 have been clarified;
— reference to ISO 23741 has been added in 5.3.1;
— new subclause 7.3 “Sampling for intermediate and final evaluation” has been added;
— requirements for the test report have been updated;
— reference to CIE 85 in Annex C has been updated to CIE 241.

iv
ISO 4892-1:2024(en)
A list of all parts in the ISO 4892 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.

v
ISO 4892-1:2024(en)
Introduction
Plastics are often used outdoors or in indoor locations where they are exposed to solar radiation or to
window-glass-filtered solar radiation 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
plastics. Outdoor exposures to solar radiation and to solar radiation filtered by window glass are described
[1]
in ISO 877 (all parts) . However, it is often necessary to rapidly determine the effects of radiation, heat and
moisture on the physical, chemical and optical properties of plastics 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 eventual 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 never reproduce exactly all the exposure stresses experienced by plastics exposed in
actual-use conditions. 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 UV 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.
vi
International Standard ISO 4892-1:2024(en)
Plastics — Methods of exposure to laboratory light sources —
Part 1:
General guidance and requirements
1 Scope
This document provides general guidance and requirements relevant to the selection and operation of the
methods of exposure described in detail in subsequent parts of the ISO 4892 series. It also specifies general
performance requirements for devices used for exposing plastics to laboratory light sources. Information
regarding performance requirements is for producers of artificial accelerated weathering or artificial
accelerated irradiation devices.
This document also provides information on the interpretation of data from artificial accelerated weathering
or artificial accelerated irradiation exposures. More specific information about methods for determining the
change in the properties of plastics after exposure and reporting these results is not part 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 291, Plastics — Standard atmospheres for conditioning and testing
ISO 2818, Plastics — Preparation of test specimens by machining
ISO 4582, Plastics — Determination of changes in colour and variations in properties after exposure to glass-
filtered solar radiation, natural weathering or laboratory radiation sources
ISO 4892-2, Plastics — Methods of exposure to laboratory light sources — Part 2: Xenon-arc lamps
ISO 4892-3, Plastics — Methods of exposure to laboratory light sources — Part 3: Fluorescent UV lamps
ISO 4892-4, Plastics — Methods of exposure to laboratory light sources — Part 4: Open-flame carbon-arc lamps
ISO 9370, Plastics — Instrumental determination of radiant exposure in weathering tests — General guidance
and basic test method
ASTM G113, Standard terminology relating to natural and artificial weathering tests of nonmetallic materials
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ASTM G113 and the following apply.
ISO and IEC maintain terminology 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/

ISO 4892-1:2024(en)
3.1
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 material would be the plastic made with the original formulation.
Note 2 to entry: A control material is sometimes referred to as control.
3.2
file specimen
portion of the material to be tested which is stored under conditions likely to cause minimal material
degradation
Note 1 to entry: These are typically dark, dry and temperate conditions.
Note 2 to entry: The file specimen is used for comparison between the exposed and unexposed states.
3.3
artificial accelerated weathering
exposure of a material in a laboratory device intended to simulate outdoor ageing faster by radiation,
temperature, and moisture, typically including liquid water
Note 1 to entry: These exposures are typically using a laboratory light source intended to simulate outdoor conditions
in an attempt to produce more rapidly the same changes that occur when the material is used in an outdoor
environment.
Note 2 to entry: The conditions can be cyclic and intensified compared with those encountered in outdoor exposure.
Note 3 to entry: The device can 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 air pollution.
3.4
artificial accelerated irradiation
exposure of a material to a light source in a laboratory device intended to simulate ageing faster by radiation,
temperature, and moisture, typically only in the form of relative humidity, but without liquid water
Note 1 to entry: These exposures are typically using a laboratory light source intended to simulate window-glass-
filtered solar radiation or radiation from interior lighting sources in an attempt to produce more rapidly the same
changes that occur when the material is used in an indoor environment.
Note 2 to entry: These exposures are commonly referred to as fading or lightfastness tests.
3.5
weathering reference material
material of known performance when exposed to solar radiation, heat and moisture
Note 1 to entry: Weathering reference materials are used for weathering and irradiation testing.
3.6
reference specimen
portion of the weathering reference material that is to be exposed
3.7
black-panel thermometer
BPT
flat, black coated metal plate which is exposed to radiation, with a temperature sensor attached to the front
centre of the exposed surface
Note 1 to entry: The intention is to mimic the thermal conditions of a coated black metal panel. The measured
temperature depends on heat fluxes by short and long wavelength radiation and convection on the front side and the
rear side of the panel.
ISO 4892-1:2024(en)
Note 2 to entry: The BPT provides a measure for the reference surface temperature of irradiated surfaces. The BPT
will typically show lower temperatures than the black-standard thermometer under the same conditions.
Note 3 to entry: Black-panel thermometers are sometimes referred to as uninsulated black-panel thermometers.
3.8
black-standard thermometer
BST
flat, black coated metal plate which is exposed to radiation, with a thermal insulation on the backside and
the temperature sensor is attached to the rear centre of the exposed plate and between metal plate and
insulation
Note 1 to entry: The intention is to mimic the thermal conditions of a common black polymer specimen. The measured
temperature depends on heat fluxes by short and long wavelength radiation and convection on the frontside of the
panel only.
Note 2 to entry: The BST will show one of the highest temperatures in the specimen plane.
Note 3 to entry: Black-standard thermometers are sometimes referred to as insulated black-panel thermometers.
3.9
white-panel thermometer
WPT
flat, white coated metal plate which is exposed to radiation, with a temperature sensor attached to the front
centre of the exposed surface
Note 1 to entry: The intention is to mimic the thermal conditions of a coated white metal panel. The measured
temperature depends on heat fluxes by short and long wavelength radiation and convection on the front side and the
rear side of the panel.
Note 2 to entry: The WPT provides a measure for the reference surface temperature of irradiated surfaces. The WPT
will typically show lower temperatures than the white-standard thermometer.
3.10
white-standard thermometer
WST
flat, white coated metal plate which is exposed to radiation, with a thermal insulation on the backside and
the temperature sensor is attached to the rear centre of the exposed plate and between metal plate and
insulation
Note 1 to entry: The intention is to mimic the thermal conditions of a common white polymer specimen. The measured
temperature depends on heat fluxes by short and long wave radiation and convection on the frontside of the panel
only.
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 shall be met for the measurement of the
irradiance and radiant exposure in the plane of the specimen, the temperature of specified white and black
surface thermometers, the chamber air temperature and the relative humidity.
NOTE In this document, the term “light source” refers to radiation sources that emit UV radiation, visible
radiation, infrared radiation or any combination of these types of radiation.
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 plastic being tested. In
addition, it is essential to consider the effects of variability in both the accelerated test and actual exposures

ISO 4892-1:2024(en)
when setting up exposure experiments and when interpreting the results from artificial accelerated
weathering or artificial accelerated irradiation exposures.
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 different depending on location
because of differences in UV 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 ISO 4892 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 A specific exposure duration or radiant exposure in an artificial accelerated weathering or artificial
accelerated irradiation exposure cannot generally be correlated to a defined duration under end use
conditions. It is therefore incorrect to assign a general acceleration factor valid for all materials. Such an
acceleration factor cannot be general 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 passbands are used) do not take into consideration the effects of
temperature, moisture and differences in relative spectral irradiance 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 exterior or indoor environmental tests and artificial accelerated
weathering or artificial accelerated irradiation exposures. Results used to relate times to failure or to a specified
property change in each exposure can be analysed using statistical methods. An example of a statistical analysis using
multiple laboratory and actual exposures to calculate an acceleration factor is described in Reference [2].
4.2.4 There are a number of factors that can 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 relative spectral irradiance of the laboratory light source and solar radiation;
[3]
NOTE ISO/TR 18486 provides information to compare a laboratory light source to a reference solar
spectrum.
b) irradiance levels higher than those experienced in actual-use conditions;
c) exposure cycles that use continuous exposure to radiation 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 with actual-use conditions;
h) absence of biological agents, pollutants or acidic precipitation or condensation.

ISO 4892-1:2024(en)
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 ISO 4892 are best used to compare the relative performance
of materials. Comparisons between materials are best made when the materials are tested at the same time
under the same conditions 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 weathering reference material reaches a specified level. If the weathering reference
material differs in composition from the test material, it can be insensitive to exposure stresses that produce
failure in the test material or it can be very sensitive to an exposure stress that has very little effect on the
test material. If that is the case, the variability in results for the weathering reference material may be very
different from that for the test material. Different sensitivities of the weathering reference material and the
test material can produce misleading results when the weathering reference material is used as a control or
to determine the length of the exposure period.
NOTE 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 weathering reference materials used for
this purpose can be found in Reference [4]. Reference [5] 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 ISO 4892 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.

ISO 4892-1:2024(en)
5 Requirements for laboratory exposure devices
5.1 Irradiance
5.1.1 Laboratory light sources are used to provide irradiance for the test specimens. In ISO 4892-2, xenon-
arc lamps are used to provide the irradiance for the specimens, in ISO 4892-3 fluorescent UV lamps and in
ISO 4892-4 open-flame sunshine carbon-arc lamps.
If necessary, optical filters are used to adjust the spectral irradiance or irradiance bandpass provided by an
artificial light source to a desired spectral irradiance such as CIE 241, CIE-H1 (see Annex C) especially for
wavelengths below the targeted UV-cut-on.
NOTE The spectral irradiance produced in an artificial accelerated weathering device is very important. Ideally,
the relative spectral irradiance produced by the device is expected to be a very close match to that of solar radiation,
especially in the short-wavelength UV region [see NOTE in 4.2.4. a)]. Annex C provides information about important
benchmark solar spectra that can be used for comparing the spectral irradiance produced in the artificial accelerated
exposure to that for solar radiation. Subsequent parts of the ISO 4892 series contain specific requirements for the
relative spectral irradiance produced in the devices described in those parts.
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.
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. The manufacturers
of exposure devices shall follow the procedures for measuring irradiance uniformity given in Annex A.
NOTE The irradiance uniformity in exposure devices depends on apparatus design and several other 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 If the minimum 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. The repositioning procedure and schedule shall be agreed upon by all interested
parties.
NOTE Reference [6] describes several possible procedures, including random positioning of replicate specimens,
that can be used to reduce the variability in exposure stresses experienced by specimens during exposure.
5.1.5 If the irradiance at any position in the area used for specimen exposure is at least 90 % of the
maximum irradiance, it is not necessary to use periodic repositioning of the specimens during exposure to
ensure uniform radiant exposure.
NOTE 1 Depending on the specific sensitivity of the material, periodic repositioning of the specimens is good
practice to minimize variability in stresses experienced during the exposure.
NOTE 2 Random placement of replicate specimens is also good practice to reduce the effect of any variability in the
conditions within the exposure area.
5.1.6 Follow the device manufacturer’s instructions for lamp and filter replacement and for pre-ageing of
lamps and/or filters.
5.1.7 A radiometer integrated in the laboratory exposure device that conforms with the requirements
outlined in ISO 9370 may be used to measure the irradiance, E, or spectral irradiance, E , and the radiant
λ
exposure, H, or spectral radiant exposure, H , in the plane of the specimen surface.
λ
NOTE ISO 9370 specifies calibration checks of the radiometer integrated in the laboratory exposure device on a
"frequent" basis.
ISO 4892-1:2024(en)
If used, this radiometer shall be formally calibrated according to ISO 9370 and adjusted at least annually,
either by an accredited laboratory, or manufacturer. Alternatively, a calibrated reference radiometer can be
used to periodically verify whether the radiometer integrated in the laboratory exposure device’s status is
still acceptable.
5.1.7.1 If used, the radiometer integrated in the laboratory exposure device 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. The radiometer
integrated in the laboratory exposure device shall be calibrated using a light source or a light source/optical
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.
A calibration of the laboratory exposure device’s irradiance control system, if used, shall be conducted
regularly. The recommended recalibration procedure and intervals can be provided by the equipment
[7]
manufacturer. ISO 10012 provides information for setting the calibration interval. When none of this
information is available, it is recommended to perform a calibration once a year. In any case, the recalibration
intervals shall be justified and documented.
This calibration shall be traceable to a recognized radiometric standards body. More frequent calibrations
are recommended.
NOTE 1 Reference [8] provides specific guidance on the calibration of radiometers using spectroradiometers. This
method can be used to calibrate the instrument radiometer(s).
NOTE 2 Refer to ISO 9370 for definitions of field and reference radiometers.
5.1.7.2 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 passband that is centred around a single wavelength
(e.g. 340 nm or 420 nm).
5.2 Temperature
5.2.1 The surface temperature of irradiated polymers depends primarily on the heat fluxes by absorbed
and emitted radiation, by convection and by thermal conduction within the specimen. Since it is not practical
to monitor the surface temperature of individual test specimens, a specified black surface thermometer is
used to measure and control the thermal conditions at this specific reference surface in the specimen plane.
The conditions within the weathering device, including the air flow, depend on the choice of this surface
thermometer. The black surface temperature sensor shall be mounted within the specimen exposure area
so that it is in the same plane and orientation and receives the same radiation as a flat test specimen surface.
For three-dimensional specimens, the black surface thermometer shall be in a plane and orientation that
best represents the majority of the specimen surface of interest or at the plane of the primary surface of
interest. The black surface thermometer is intended to approximate the highest temperature experienced
by test specimens in the specimen plane.
5.2.2 Two types of black surface temperature sensors may be used: black-standard thermometer (BST)
and 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 irradiated surface of this plate
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 light source. This side of the metal plate shall be attached to a 5 mm thick base plate made
of unfilled poly(vinylidene fluoride) (PVDF). A small space sufficient to hold the platinum resistance sensor
shall be machined in the PVDF base plate. The
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