ISO 22785-5:2026

• Abstract:

  This document specifies chemical resistance testing of coatings on plastics, plastics composites and similar substrates, hereinafter collectively referred to as plastics. This document shows the potential effect of plastics on the behaviour of the coating during chemical resistance testing.

• Status: Published
• Publication Date: 02-Aug-2026
• ICS: 83.080.01 - Plastics in general
• ICS: 83.120 - Reinforced plastics
• ICS: 87.040 - Paints and varnishes
• Technical Committee: ISO/TC 35/SC 9 - General test methods for paints and varnishes
• Drafting Committee: ISO/TC 35/SC 9/WG 31 - Properties after application
• Current Stage: 6060 - International Standard published
• Start Date: 03-Aug-2026
• Due Date: 06-May-2027
• Completion Date: 03-Aug-2026

ISO 22785-5:2026 is an ISO International Standard for chemical resistance testing of coatings on plastics, plastics composites and similar substrates. It specifies how to test these coatings and how the plastic substrate can influence coating behaviour during exposure. It is intended for laboratories, coating suppliers, and users who need comparable results for coated plastic parts.

What does ISO 22785-5:2026 specify?

ISO 22785-5:2026 specifies chemical resistance testing for coatings on plastics, plastics composites and similar substrates, collectively called plastics. It also explains that the substrate itself can affect how the coating behaves during the test.

The document is organized into:

• Clause 1 - Scope
• Clause 2 - Normative references
• Clause 3 - Terms and definitions
• Clause 4 - Sample composition and preparation
• Clause 5 - Methods for testing
• Clause 6 - Chemicals for testing
• Clause 7 - Evaluation
• Bibliography

In practice, that structure takes the reader from specimen preparation to exposure, then to inspection and follow-up checks.

What are the key requirements of ISO 22785-5:2026?

ISO 22785-5:2026 sets out how to prepare samples, choose a test method, select test chemicals, and judge the result. The key point is that the plastic substrate is part of the test outcome, not just the coating.

Sample preparation and conditioning

Clause 4 states that coatings on ISO 1514 specimen plates and on components may be tested. For continuous drip methods and exposure through filter papers, flat specimens are needed, so the part geometry has to match the method.

Clause 4 also requires careful preparation of the coating system and substrate so the coating is homogeneous, with coating thickness documented. Edges and backsides need protection for immersion methods. Samples are normally conditioned for 16 h in the standard climate specified in ISO 3270 unless otherwise specified.

Test methods

Clause 5 covers immersion, an absorbent medium, spotting methods, a temperature-gradient oven method, and chemical load testing of electrical and electronic equipment. The reader chooses the method based on the product and the exposure scenario.

The standard points to the relevant method documents - for example ISO 2812-1, ISO 2812-2, ISO 2812-3, ISO 2812-4 and ISO 2812-5, plus ISO 16750-5 for electrical and electronic equipment. In practice, this means the method details come from those parts, while ISO 22785-5 adds the plastics-specific guidance.

Clause 5 also stresses temperature sensitivity. Plastics can soften or change state more easily than metals, so the test temperature has to keep the substrate in the same condition as in use.

Chemicals and exposure media

Clause 6 groups the test media into fuels and operating materials, laboratory chemicals, biological substances, and substances of daily use. It states that only analytical reagent grade chemicals are used, while commercial products are used for fuels, operating materials, and everyday-use substances.

For non-automotive applications, the chemical resistance test has to be adapted to the actual service environment and documented in the test report. That matters because the test fluid should represent the real exposure, not just a standard list.

Evaluation and substrate influence

Clause 7 requires visual assessment after exposure. It also points to gloss measurement, colour measurement, and haze measurement, and allows additional agreed tests such as scratch resistance, cross-cut, and contact angle.

The clause also explains why plastics can change test results. Plastics may heat differently from metals, and they can swell or shrink when exposed to the test substance, which can affect appearance, adhesion, glass transition temperature, and other properties.

What terms does ISO 22785-5:2026 define?

ISO 22785-5:2026 uses the terminology in ISO 4618 and ISO 22785-1. The following terms are central to how the document is applied:

• Plastics - In this document, plastics includes plastics, plastics composites, and similar substrates.
• Conditioning - Holding the test specimens before exposure so the results are more repeatable and reproducible.
• Absorbent medium - A carrier used to apply test substances to a panel in the ISO 2812-3 method.
• Temperature-gradient oven method - An exposure method in which a panel is heated from below in a gradient oven.
• Glass transition temperature - The temperature region where a plastic changes behaviour, which affects test temperature selection.
• Reflow storage - An agreed elevated-temperature storage step used before re-evaluation after exposure.

Who uses ISO 22785-5:2026?

ISO 22785-5:2026 is used by coating laboratories, paint and varnish manufacturers, plastics and composites producers, and quality teams that need to verify chemical resistance on coated plastic parts. It is also relevant to automotive-related testing, because the document includes fuels, oils, cleaners, and other operating materials.

Engineers and buyers use it when specifying test methods for coated plastic components. Test labs use it when preparing samples, selecting exposure media, and reporting visual and functional changes after testing.

Which standards are used with ISO 22785-5:2026?

ISO 22785-5:2026 refers to ISO 4618 and ISO 22785-1 for terminology and the general framework for coatings on plastics and composites. It also uses several method and measurement standards in the body of the document, including:

• ISO 1514 for standard panels
• ISO 3270 for conditioning climate
• ISO 2812-1 to ISO 2812-5 for liquid resistance test methods
• ISO 16750-5 for chemical loads on electrical and electronic equipment
• ISO 2813 for gloss
• ISO 18314-1 for colour measurement
• ISO 13803 for haze
• ISO 1518-1, ISO 1518-2, ISO 2409 and ISO 19403-2 for optional follow-up tests
• ISO 3696 for laboratory water

What does the ISO 22785-5:2026 document contain?

ISO 22785-5:2026 contains practical guidance for preparing coated plastic specimens, choosing a chemical resistance test method, selecting exposure media, and evaluating the result. It includes specific guidance on how sample geometry, conditioning, and substrate thermal behaviour affect the test.

The document also contains long lists of test chemicals grouped by use, including fuels, laboratory chemicals, biological substances, and substances of daily use. Its evaluation section ties visual inspection to gloss, colour, haze, and agreed functional tests, so the result can be judged in a way that fits the intended application.

International
Standard
ISO 22785-5
First edition
Paints and varnishes — Coatings on
2026-08
plastics and composites —
Part 5:
Chemical resistance testing
Peintures et vernis — Revêtements sur plastiques et
composites —
Partie 5: Essais de résistance aux produits chimiques
Reference number
© 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
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or ISO’s member body in the country of the requester.
ISO copyright office
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CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Sample composition and preparation . 1
4.1 Samples .1
4.2 Conditioning.2
5 Methods for testing . 2
5.1 General influences .2
5.2 Immersion into the test chemicals or solution.2
5.3 Method using an absorbent medium .2
5.4 Spotting methods .2
5.5 Temperature-gradient oven method .2
5.6 Chemical load of electrical and electronic equipment .3
6 Chemicals for testing . 3
6.1 General .3
6.2 Fuels and operating materials .3
6.3 Laboratory chemicals .4
6.4 Biological substances . .4
6.5 Substances of daily use .4
7 Evaluation . 5
7.1 General .5
7.2 Influence of the plastics substrate on the chemical resistance test .5
7.2.1 General .5
7.2.2 Temperature sensitivity .5
7.2.3 Volume change due to test substances .5
Bibliography . 7

iii
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
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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 document 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 35, Paints and varnishes, Subcommittee SC 9,
General test methods for paints and varnishes.
A list of all parts in the ISO 22785 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
Introduction
The ISO 22785 series explains the characteristics of plastics and the differences between plastics substrates
and metallic substrates.
Even though chemical resistance testing is usually a surface test, the substrate has an influence on the
chemical resistance of the coating and is also considered during the test.

v
International Standard ISO 22785-5:2026(en)
Paints and varnishes — Coatings on plastics and
composites —
Part 5:
Chemical resistance testing
1 Scope
This document specifies chemical resistance testing of coatings on plastics, plastics composites and similar
substrates, hereinafter collectively referred to as plastics.
This document shows the potential effect of plastics on the behaviour of the coating during chemical
resistance testing.
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 4618, Paints and varnishes — Vocabulary
ISO 22785-1, Paints and varnishes — Coatings on plastics and composites — Part 1: General introduction
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4618 and ISO 22785-1 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/
4 Sample composition and preparation
4.1 Samples
Coatings on specimen plates specified in ISO 1514 as well as coatings on components are tested. Depending
on the selected test method, there are different requirements for the sample geometry. In particular, for
continuous drip methods and exposure through filter papers, flat specimens are a prerequisite.
Defects and damage of all kinds in the substrate affect the appearance and characteristics.
The coating system and the substrate are selected together with the pre-treatment and coating methods so
that a homogeneous coating is achieved. The coating thick
...