SIST EN ISO 877-3:2026

• Abstract:

  This document specifies a method for exposing plastics to concentrated solar radiation using reflecting concentrators to accelerate the weathering processes. The purpose is to assess property changes produced after specified stages of such exposures. The reflecting concentrators used in these exposures are sometimes referred to as “Fresnel reflectors” because, in cross-section, the array of mirrors used to concentrate the solar radiation resembles the cross-section of a Fresnel lens.; General guidance concerning the scope of the ISO 877 series is given in ISO 877-1.; NOTE Additional information about solar concentrating exposures, including a partial list of standards in which they are specified, is given in the Bibliography.

• Status: Published
• Public Enquiry End Date: 22-Sep-2025
• Publication Date: 18-Jun-2026
• ICS: 83.080.01 - Plastics in general
• Technical Committee: IPMA - Polimer materials and products
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 10-Jun-2026
• Due Date: 15-Aug-2026
• Completion Date: 19-Jun-2026
• Ref Project: EN ISO 877-3:2026 - Plastics - Methods of exposure to solar radiation - Part 3: Intensified weathering using concentrated solar radiation (ISO 877-3:2026)

• Referred By: SIST EN 15132:2007 - Container shells for mobile waste containers with a capacity up to 1 700 l - Performance requirements and test methods
• Effective Date: 03-Jun-2026
• Referred By: SIST EN 10245-1:2012 - Steel wire and wire products - Organic coatings on steel wire - Part 1: General rules
• Effective Date: 03-Jun-2026
• Referred By: SIST-TS CEN/TS 15354:2006 - Plastics - Extruded and/or calendered, non-reinforced film and sheeting made of plasticized poly(vinyl chloride) (PVC-P) - Guidance for characterisation and designation
• Effective Date: 03-Jun-2026
• Referred By: SIST-TS CEN/TS 15534-1:2007 - Wood-plastics composites (WPC) - Part 1: Test methods for characterisation of WPC materials and products
• Effective Date: 03-Jun-2026
• Referred By: SIST-TS CEN/TS 15534-3:2007 - Wood-plastics composites (WPC) - Part 3: Characterisation of WPC products
• Effective Date: 03-Jun-2026
• Referred By: SIST EN 15354:2022 - Plastics - Extruded and/or calendered, non-reinforced film and sheeting made of plasticized poly(vinyl chloride) (PVC-P) - Characterization and designation
• Effective Date: 03-Jun-2026
• Referred By: SIST EN 62282-4-101:2014 - Fuel cell technologies - Part 4-101: Fuel cell power systems for propulsion other than road vehicles and auxiliary power units - Fuel cell power systems for electrically powered industrial trucks - Safety
• Effective Date: 03-Jun-2026
• Revises: SIST EN ISO 877-3:2018 - Plastics - Methods of exposure to solar radiation - Part 3: Intensified weathering using concentrated solar radiation (ISO 877-3:2018)
• Effective Date: 25-Oct-2023

SIST EN ISO 877-3:2026 is the Slovenian adoption of EN ISO 877-3:2026, published by SIST. It specifies a method for exposing plastics to concentrated solar radiation with reflecting concentrators so that weathering can be accelerated and property changes can be assessed after defined exposure stages. The standard is intended for laboratories, manufacturers and other users who need a controlled outdoor weathering test for plastics.

What does SIST EN ISO 877-3:2026 specify?

SIST EN ISO 877-3:2026 covers intensified weathering of plastics using concentrated solar radiation. The reflecting concentrators used in this method are sometimes called Fresnel reflectors because the mirror array resembles a Fresnel lens in cross-section.

The document is organized into clauses covering scope, normative references, principle, apparatus, test specimens, exposure conditions, exposure stages, procedure, expression of results and test report, followed by a bibliography. General guidance for the ISO 877 series is given in ISO 877-1.

What are the key requirements of SIST EN ISO 877-3:2026?

Exposure method and apparatus

SIST EN ISO 877-3:2026 requires exposure of plastics to intensified solar radiation as an accelerated weathering method. Clause 5 ties the concentrating device, its operation and the measurement of solar radiation in the specimen exposure area to ASTM G90, while the climatic measurement apparatus follows ISO 877-1.

This matters because the method depends on a defined concentrating system rather than general outdoor exposure. Users need a device and measurement setup that match the standard if they want comparable results.

Clause 5 also shows two apparatus layouts, one with single-axis tracking and manual elevation adjustment and one with dual-axis tracking. That helps users and test laboratories match the exposure system to the kind of test being run.

Test specimens and mounting

Clause 6 says test specimens follow ISO 877-1. Clause 9 then requires the exposed faces to be oriented toward the mirrors and the specimens to be mounted so the clamping fixture covers as little of the specimen as practical.

The mounting details matter because airflow and cooling affect how hot the specimen gets. The standard distinguishes between unbacked exposures and insulated, backed exposures, so users must choose holders and backing materials with the exposure mode in mind.

For backed exposures, the backing material must be insulating and water-resistant. The document also limits the overall thickness of the specimen assembly so that the concentrating device can cool the specimen adequately.

Exposure conditions and exposure stages

Clause 7 sets the exposure conditions. Mirror orientation follows ASTM G90, exposure sites are chosen for locations with strong sunshine and low daytime humidity, and temperature control may use black-panel, black-standard, specimen or air-temperature measurement depending on the arrangement used.

This matters in practice because site selection and temperature control change the severity of the exposure. If a test uses modified temperature control or altered irradiance, the report has to describe that clearly so the results can be interpreted correctly.

Clause 8 defines exposure stages in terms of accumulated solar radiant exposure, solar UV radiant exposure or UV radiant exposure in a narrow passband. Table 1 helps users choose stages by relating them to reference climates, and the document notes that exposure start time and season affect how quickly the target exposure is reached.

Water spray cycles and under-glass testing

Clause 9.4.2 uses water spray cycles selected from Table 2. The cycles cover a wet-dry cycle with night sprays, a shorter night-only cycle, no spray, and other cycles agreed by the interested parties.

The notes to Table 2 show how the cycles are used in practice. They are intended for different product types and appearances, including general plastics specimens, high-gloss materials such as automotive lens materials, transparent sheet, under-glass exposures, plastics-laminated glass, fade-only tests and inner covers of solar hot-water collectors.

Clause 9.4.3 covers testing under glass. When this mode is used, the glass characteristics must follow ISO 877-2, and the glass transmission has to be reported. That is important because under-glass exposure changes the radiation reaching the specimen.

Measurement, results and reporting

Clause 10.1 points users to ISO 4582 for determining changes in colour and other properties after exposure. Clause 10.2.4 gives formulae for calculating exposure levels from mirror configuration and measured daily solar exposure, and clause 10.2.5 specifies how total solar radiation and solar UV radiation are measured.

For users, this means the exposure is defined by measured radiant exposure, not only by time outdoors. The report then has to record the spray cycle used, temperature-control details, any irradiance reduction, and the transmission of glass used for under-glass exposures.

What terms does SIST EN ISO 877-3:2026 define?

SIST EN ISO 877-3:2026 uses these key terms for its exposure method and measurements.

• Reflecting concentrators - Mirror assemblies that focus solar radiation onto the specimen exposure area to intensify weathering.
• Fresnel reflectors - A common name for the reflecting concentrators used in this method because of their mirror geometry.
• Solar radiant exposure - The accumulated solar energy delivered to a specimen area, used to define exposure stages.
• Solar UV radiant exposure - The accumulated ultraviolet component of solar energy used for staging and comparison of exposures.
• Black-panel thermometer - A temperature-measuring device used to monitor specimen or exposure conditions during the test.
• Black-standard thermometer - A standard temperature sensor arrangement used when more precise temperature control is required.
• Time of wetness - The period during which the specimen remains wet during exposure and observation.

Who uses SIST EN ISO 877-3:2026?

SIST EN ISO 877-3:2026 is used by plastics laboratories, weathering test laboratories and manufacturers that need accelerated outdoor exposure data for plastics. It is relevant to material developers comparing formulations, stabilizers or surface finishes, because the method is designed to show property changes after defined exposure stages.

The document is also useful in sectors named in the procedure notes, including automotive lens materials, transparent sheet, plastics-laminated glass and solar hot-water collector components. Quality and technical teams use it when they need a documented exposure method for product qualification or comparative testing.

What changed in SIST EN ISO 877-3:2026 from the previous edition?

SIST EN ISO 877-3:2026 is the third edition and it cancels and replaces ISO 877-3:2018. The main technical changes stated in the document are the addition of size requirements in 7.3, the addition of a second formula in 10.2.4, and the addition of a new 10.2.5 on radiation measurement, with the later clauses renumbered.

The European foreword also states that EN ISO 877-3:2026 supersedes EN ISO 877-3:2018.

Which standards are used with SIST EN ISO 877-3:2026?

Standard	What it contributes
ISO 877-1	General guidance for the ISO 877 series, including climatic observations and the test report framework.
ISO 877-2:2025	Guidance for direct weathering and exposure behind window glass, used when under-glass testing is performed.
ISO 4892-1	Requirements for black- or white-standard thermometers when those are used for temperature control.
ASTM G90	Core requirements for the concentrating device, orientation of mirrors, exposure site, irradiance measurement and device operation.
ASTM G179	Construction, calibration and maintenance of black- or white-panel temperature devices.

Clause 10.1 also points users to ISO 4582 for determining changes in properties after exposure, and the bibliography cites ISO 9370:2017 for instrumental determination of radiant exposure in weathering tests.

What does the SIST EN ISO 877-3:2026 document contain?

The document includes schematic figures for single-axis and dual-axis concentrating apparatus, plus a figure showing how the reflecting mechanism works. It also includes a table for selecting exposure stages from reference climate data and a table of water spray cycles with their typical uses.

It provides the procedure for mounting specimens, mounting reference materials if used, making climatic observations, running exposure cycles and testing under glass. Clause 10 then sets out how to express results, and clause 11 sets out the test report items that must be recorded for later comparison or audit of the exposure conditions.

SLOVENSKI STANDARD
01-julij-2026
Polimerni materiali - Metode izpostavitve vremenskim vplivom - 3. del: Pospešeni
vremenski vplivi z uporabo koncentriranega sončnega sevanja (ISO 877-3:2026)
Plastics - Methods of exposure to solar radiation - Part 3: Intensified weathering using
concentrated solar radiation (ISO 877-3:2026)
Kunststoffe - Freibewitterung - Teil 3: Beschleunigte Bewitterung mit gebündelter
Sonnenstrahlung (ISO 877-3:2026)
Plastiques - Méthodes d'exposition au rayonnement solaire - Partie 3: Exposition
intensifiée par rayonnement solaire concentré (ISO 877-3:2026)
Ta slovenski standard je istoveten z: EN ISO 877-3:2026
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 877-3
EUROPEAN STANDARD
NORME EUROPÉENNE
May 2026
EUROPÄISCHE NORM
ICS 83.080.01 Supersedes EN ISO 877-3:2018
English Version
Plastics - Methods of exposure to solar radiation - Part 3:
Intensified weathering using concentrated solar radiation
(ISO 877-3:2026)
Plastiques - Méthodes d'exposition au rayonnement Kunststoffe - Freibewitterung - Teil 3: Beschleunigte
solaire - Partie 3: Exposition intensifiée par Bewitterung mit gebündelter Sonnenstrahlung (ISO
rayonnement solaire concentré (ISO 877-3:2026) 877-3:2026)
This European Standard was approved by CEN on 20 May 2026.

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
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 877-3:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 877-3:2026) 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 November 2026, and conflicting national standards
shall be withdrawn at the latest by November 2026.
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 877-3:2018.
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 877-3:2026 has been approved by CEN as EN ISO 877-3:2026 without any modification.

International
Standard
ISO 877-3
Third edition
Plastics — Methods of exposure to
2026-05
solar radiation —
Part 3:
Intensified weathering using
concentrated solar radiation
Plastiques — Méthodes d'exposition au rayonnement solaire —
Partie 3: Exposition intensifiée par rayonnement solaire
concentré
Reference number
ISO 877-3:2026(en) © ISO 2026
ISO 877-3:2026(en)
© ISO 2026
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 877-3:2026(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
5.1 General requirements .2
5.2 Apparatus for measurement of climatic factors .3
6 Test specimens . 3
7 Exposure conditions . 4
7.1 Orientation of mirrors .4
7.2 Exposure site.4
7.3 Temperature control .4
7.4 Irradiance level .5
8 Exposure stages . 6
8.1 General .6
8.2 Solar radiant exposure .6
8.2.1 Guidance for selection of the exposure stage .6
8.2.2 Instrumental measurement of solar radiant exposure .6
9 Procedure . 7
9.1 Mounting of test specimens .7
9.2 Mounting of reference materials (if used) .7
9.3 Climatic observations .7
9.4 Exposure of test specimens .7
9.4.1 General .7
9.4.2 Exposure cycles .7
9.4.3 Testing under glass.7
10 Expression of results . 8
10.1 Determination of changes in properties .8
10.2 Climatic conditions and observations .8
10.2.1 General .8
10.2.2 Temperature .8
10.2.3 Relative humidity .8
10.2.4 Levels (values) of exposure stages .8
10.2.5 Radiation measurement.9
10.2.6 Precipitation .9
10.2.7 Time of wetness .9
10.2.8 Other observations .9
11 Test report . 9
Bibliography .10

iii
ISO 877-3:2026(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 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 third edition cancels and replaces the second edition (ISO 877-3:2018), which has been technically
revised.
The main changes are as follows:
— size requirements in 7.3 have been added;
— in 10.2.4, a second formula has been added;
— a new 10.2.5 “Radiation measurement” has been added and subsequent clauses have been renumbered.
A list of all parts in the ISO 877 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
International Standard ISO 877-3:2026(en)
Plastics — Methods of exposure to solar radiation —
Part 3:
Intensified weathering using concentrated solar radiation
1 Scope
This document specifies a method for exposing plastics to concentrated solar radiation using reflecting
concentrators to accelerate the weathering processes. The purpose is to assess property changes produced
after specified stages of such exposures. The reflecting concentrators used in these exposures are sometimes
referred to as “Fresnel reflectors” because, in cross-section, the array of mirrors used to concentrate the
solar radiation resembles the cross-section of a Fresnel lens.
General guidance concerning the scope of the ISO 877 series is given in ISO 877-1.
NOTE Additional information about solar concentrating exposures, including a partial list of standards in which
they are specified, is given in the Bibliography.
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 877-1, Plastics — Methods of exposure to solar radiation — Part 1: General guidance
ISO 877-2:2025, Plastics — Methods of exposure to solar radiation — Part 2: Direct weathering and exposure
behind window glass
ISO 4892-1, Plastics — Methods of exposure to laboratory light sources — Part 1: General guidance and
requirements
ASTM G90, Standard Practice for Performing Accelerated Outdoor Weathering of Nonmetallic Materials Using
Concentrated Natural Sunlight
ASTM G179, Standard Specification for Metal Black Panel and White Panel Temperature Devices for Natural
Weathering Tests
3 Terms and definitions
No terms and definitions are listed in this document.
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/
4 Principle
This document describes a method for performing accelerated weathering on plastics using intensified solar
radiation. General guidance is given in ISO 877-1.

ISO 877-3:2026(en)
5 Apparatus
5.1 General requirements
General
...