ISO/TR 21555:2019
(Main)Paints and varnishes - Overview of test methods on hardness and wear resistance of coatings
Paints and varnishes - Overview of test methods on hardness and wear resistance of coatings
This document provides an overview for selecting the most suitable test method regarding the evaluation of the hardness and the wear resistance of coatings. Annex A gives a summarized list of test methods for the evaluation of the hardness and of the wear resistance of coatings for different stresses. Methods for testing cross-linking (wear test in connection with solvents) and abrasion tests with multiple impacts are not covered by this document.
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TECHNICAL ISO/TR
REPORT 21555
First edition
2019-08
Paints and varnishes - Overview of
test methods on hardness and wear
resistance of coatings
Reference number
©
ISO 2019
© ISO 2019
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ii © ISO 2019 – All rights reserved
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Hardness tests . 2
4.1 Indentation tests with resting indenter . 2
4.1.1 Indentation test with Buchholz indenter. 2
4.1.2 Indentation test with Knoop indenter . 5
4.1.3 Indentation test with Pfund indenter . 6
4.1.4 Indentation test with Vickers indenter . 8
4.2 Indentation tests with oscillating indenter .10
4.2.1 Oscillation damping test with König pendulum .10
4.2.2 Oscillation damping test with Persoz pendulum .11
4.2.3 Oscillation damping test with rocker .13
5 Wear resistance tests .14
5.1 Single-scratch tests .14
5.1.1 Scratch test with pencils .14
5.1.2 Scratch test with ball stylus 1 .17
5.1.3 Scratch test with ball stylus 2 .20
5.1.4 Scratch test with conical stylus 3 .22
5.1.5 Scratch test with conical stylus 4 .25
5.1.6 Scratch test with conical stylus 5 .28
5.1.7 Scratch test with conical stylus 6 .31
5.1.8 Scratch test with disc-shaped stylus .33
5.1.9 Scratch test with U-shaped stylus .37
5.2 Multiple scratch tests .39
5.2.1 Multiple scratch test with locked abrasive wheel .39
5.2.2 Multiple scratch test with abrasive cylinder .40
5.2.3 Multiple scratch test with rotating abrasive wheels .42
5.2.4 Multiple scratch test with rotating brush .43
5.3 Dry abrasion tests .45
5.3.1 Abrasion test with locked abrasive wheel .45
5.3.2 Abrasion test with rotating abrasive wheels 1 .47
5.3.3 Abrasion test with abrasive wheels 2 .48
5.3.4 Abrasion test with rotating abrasive wheels 3 .50
5.3.5 Abrasion test with rotating abrasive wheels 4 .51
5.4 Wet abrasion tests .53
5.4.1 Scrub test with brush .53
5.4.2 Scrub test with non-woven web 1 .55
5.4.3 Scrub test with non-woven web 2 .57
5.5 Falling-sand tests .60
5.5.1 Falling-sand test with corundum granulate .60
5.5.2 Falling-sand test with quartz sand .62
Annex A (informative) Overview on test methods on hardness and wear resistance of coatings .64
Bibliography .69
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).
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 (see 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 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.
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 © ISO 2019 – All rights reserved
Introduction
The determination of the hardness and of the wear resistance is one of the most important preconditions
for evaluating the resistance of coatings to mechanical stress.
The procedures and numerical data given in this document provide a rough overview; detailed
information is found in the applicable standards.
For all of the methods for the evaluation of the hardness and of the wear resistance the visco-elastic
properties have a wide influence on the test result. Consequently, the time between testing and
evaluation are agreed and observed.
Mechanical properties of coatings depend on, among others, temperature and moisture content.
Consequently, the tests should be carried out immediately after the conditioning phase.
The tests are preferably carried out in the climatic chamber.
Each method has its specific application. An unsuitable method may lead to false conclusions. All of the
test methods require a certain expertise of the test person. For most of the test methods the test results
depend on, among others, the film thickness of the coating to be tested.
TECHNICAL REPORT ISO/TR 21555:2019(E)
Paints and varnishes - Overview of test methods on
hardness and wear resistance of coatings
1 Scope
This document provides an overview for selecting the most suitable test method regarding the
evaluation of the hardness and the wear resistance of coatings.
Annex A gives a summarized list of test methods for the evaluation of the hardness and of the wear
resistance of coatings for different stresses.
Methods for testing cross-linking (wear test in connection with solvents) and abrasion tests with
multiple impacts are not covered by 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 4618, Paints and varnishes — Terms and definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4618 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
hardness
ability of a dry film or coat to resist indentation or penetration by a solid object
[SOURCE: ISO 4618:2014, 2.136]
3.2
wear
irreversible change of a coating which is caused by the mechanical impact of moved objects
3.3
stylus
scratching tool with specified geometry
[SOURCE: ISO 22557:2019, 3.1]
3.4
scratch
line-shaped damage of a coating which is caused by the impact of a loaded object being moved over
the coating
3.5
mar
blemish on the surface of a coating, extending over a particular area of the coating and visible due to
the difference in the light-reflection properties of the area affected compared with the light-reflection
properties of adjacent areas
[SOURCE: ISO 4618:2014, 1.152]
3.6
abrasion
wear (3.2) which is caused by removal of coating material on a surface
3.7
repeatability conditions
conditions where independent test results are obtained with the same method on identical test items
in the same laboratory by the same operator using the same equipment within short intervals of time
[SOURCE: ISO 5725-1:1994, 3.14]
3.8
repeatabilit
...
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