ISO 22785-4:2026

International
Standard
ISO 22785-4
First edition
Paints and varnishes — Coatings on
2026-08
plastics and composites —
Part 4:
Abrasion and scratch testing
Peintures et vernis — Revêtements sur plastiques et
composites —
Partie 4: Essais d'abrasion et de rayure
Reference number
© ISO 2026
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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 . 2
4.1 Samples .2
4.2 Influence of substrate.2
4.3 Surface condition .2
4.4 Conditioning.2
4.5 Ageing .2
5 Overview of test methods . 3
5.1 Linear abrasion method — linear abrasion tester .3
5.1.1 General .3
5.1.2 Test environment .3
5.1.3 General technical characteristics .3
5.2 Hand abrasion tester .4
5.2.1 General .4
5.2.2 General technical characteristics .4
5.2.3 Particularities .5
5.2.4 Possible sources of error .5
5.3 Scratch tests .5
5.3.1 Manual scratch tests .5
5.3.2 Automatic scratch tests .7
5.4 Rotating abrasion method .8
5.4.1 Taber test.8
5.4.2 Wash scratch resistance .9
5.4.3 Martindale test.10
6 Methods for the evaluation after testing .11
6.1 General .11
6.2 Visual methods .11
6.3 Colour measurement .11
6.4 Gloss measurement .11
6.5 Haze measurement . 12
6.6 Gravimetric methods . 12
Bibliography .13

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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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).
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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.
v
International Standard ISO 22785-4:2026(en)
Paints and varnishes — Coatings on plastics and
composites —
Part 4:
Abrasion and scratch testing
1 Scope
This document specifies the abrasion and scratch tests 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 abrasion and
scratch 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, ISO 22785-1 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/
3.1
abrasion resistance
resistance of solid surfaces to mechanical stress, in particular friction
Note 1 to entry: The abrasion resistance is determined by the surface characteristics of the substances involved, such
as roughness and hardness.
3.2
abrasion test
test method which serves for the determination of the abrasion resistance (3.1)
Note 1 to entry: Abrasion can be tested together with various stresses, e.g. media. The stress is normally applied
in parallel and can be applied in different ways. The evaluation is specified respectively, since there are different
evaluation methods (optical change of colour, gloss, transmission/haze, loss of mass).

3.3
surface condition
totality of surface characteristics such as grain, gloss, and roughness
Note 1 to entry: The surface condition has a great influence on the abrasion behaviour.
4 Sample composition and preparation
4.1 Samples
Coatings on specimen plates as specified in ISO 1514 as well as coatings on components are tested. Defects
and damage of all kinds in the substrate affect the appearance and characteristics. The surface shall be
free of any substances that can impair the adhesion of the coating. Likewise, the surface shall be free from
substances sweating out or migrating to the surface over a longer period, potentially due to exposure to
moisture or temperature.
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 thickness is documented according to the optical or
coating requirement.
Components and samples which are not flat are selected to avoid bending during the test.
4.2 Influence of substrate
The elasticity of the plastics substrate has an influence on the abrasion and scratch resistance of the coating
under test. Typically, the scratch resistance of the coating decreases as the elasticity of the substrate
increases.
4.3 Surface condition
For most abrasion tests, samples with a flat uniform surface are used. Depending on the surface condition or
type of plastic, only certain tests are reasonable.
For retests, the same surface condition of the samples is considered.
4.4 Conditioning
Conditioning serves to increase the repeatability and reproducibility of test results.
The values and times to be selected depend on the material to be tested.
Since the characteristics of plastics substrates strongly depend on humidity and conditioning that usually
takes longer than for metals, a longer conditioning time is normally used for plastics substrates.
Unless otherwise specified, the samples are conditioned for 16 h in the standard climate specified in
ISO 3270.
4.5 Ageing
For some tests and materials, it can be reasonable to use special atmospheres for upstream ageing or drying.
This is shall be documented in the test report.

5 Overview of test methods
5.1 Linear abrasion method — linear abrasion tester
5.1.1 General
By means of a linear abrasion tester as specified in ISO 21546 (see Figure 1), a specified load is applied with
a parallel movement. Testers which can perform a linear back and forth movement (double stroke) with a
suitable friction partner are suitable for the determination of the abrasion resistance. Often the name of
the historically used tester “crockmeter” is used colloquially as the name (“crockmeter test”) for the tests.
There are a variety of testers which are used and reproduce the required conditions.
Key
1 crank mechanism (crank handle)
2 abrasion tool
3 test specimen
a
Direction of stroke motion.
Figure 1 — Crockmeter (example with manual crank mechanism)
5.1.2 Test environment
Carry out the test at a temperature of (23 ± 2) °C. Measure the relative humidity during the test and record
in the test report. In case of high relative humidity, be careful that no condensation water forms on the test
specimen due to falling below the dew point.
Carry out the test as quick as possible, however, not later than 30 min after the conditioning phase.
5.1.3 General technical characteristics
The following adjustable parameters shall be agreed between the interested parties:
— stress (adjustable depending on the device, historically 9 N, additional 1 N to 40 N possible);
— friction path (historically 104 mm, many devices freely adjustable);
— total number of double strokes;
— number of double strokes per time unit;
— friction partner, e.g. cotton fabric, felt, metal, abrasive paper;
— rubbing finger, e.g. rubbing finger A: 16 mm plastic, rubbing finger C: holder for abrasive paper;
— media (dry, wet, cleaning agent, etc.).
Interim assessments are recommended according to internal guidelines.

5.2 Hand abrasion tester
5.2.1 General
These testers simulate hand abrasion by a combination of mechanical and chemical load on the surface.
During this process, a silicone stamp is used to replicate the pliability of the human fingers while the fabric
simulates the roughness and greasiness of the skin. Depending on the requirements, additional media are
used, such as hand sweat and hand cream.
A stamp hits the surface to be tested at a 45° angle (see Figure 2) and runs over it. The supplementary
media, if appropriate, can be applied eit
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