ISO/FDIS 4624

Paints and varnishes — Pull-off test for adhesion

ISO 4624:2016 specifies three methods (i.e. one dolly or two dollies on a painted panel and two dollies, one as painted substrate) for determining the adhesion by carrying out a pull-off test on a single coating or a multi-coat system of paint, varnish or related product. These test methods have been found useful in comparing the adhesion behaviour of different coatings. It is most useful in providing relative ratings for a series of coated panels exhibiting significant differences in adhesion. The test may be applied using a wide range of substrates. Different procedures are given according to whether the substrate is deformable, for example thin metal, plastics and wood, or rigid, for example thick concrete and metal plates. To avoid distortion of the substrate during the tensile test, it is common to use a sandwich construction. For example, for special purposes, the coating may be applied directly to the face of a test dolly.

Peintures et vernis — Essai de traction

ISO 4624:2016 spécifie trois méthodes (par exemple un plot ou deux plots sur un panneau peint et deux plots, l'un étant utilisé comme subjectile peint d'essai) pour déterminer l'adhérence par un essai de traction sur une couche unique ou sur un système multicouche de peintures, vernis ou produits assimilés. Ces méthodes d'essai se sont révélées utiles pour comparer l'adhérence de diverses couches. Elles sont surtout utiles pour fournir des classifications relatives pour une série de panneaux revêtus présentant des différences d'adhérence significatives. L'essai peut être effectué sur une large variété de subjectiles. Différents modes opératoires sont présentés selon que le subjectile est déformable, par exemple métal, plastique et bois, ou rigide, par exemple béton épais et plaques de métal. Pour éviter la déformation du subjectile durant l'essai de traction, on utilise habituellement une construction en sandwich. Par exemple, pour des besoins particuliers, le revêtement peut être appliqué directement sur un plot d'essai.

General Information

• Status: Not Published
• 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 - General test methods for paints and varnishes
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 01-Mar-2023
• Completion Date: 01-Mar-2023

Relations

• Revises: ISO 4624:2016 - Paints and varnishes — Pull-off test for adhesion
• Effective Date: 06-Jun-2022

Standards Content (Sample)

2023-01-12 Style Definition: Heading 1: Indent: Left: 0 pt, First
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ISO/DISFDIS 4624:20222023(E)
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ISO TC 35/SC 9/WG 31
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Date: 2023-02-14
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Secretariat: BSI
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Paints and varnishes — Pull-off test for adhesion
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Peintures et vernis — Essai de traction
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ISO/DIS FDIS 4624:20222023(E)
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© ISO 20222023 Color(RGB(33;29;30))
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ISO/DIS FDIS 4624:20222023(E)
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Contents
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Foreword ..................................................................................................................................................................... iv

Introduction ................................................................................................................................................................. v

1 Scope ................................................................................................................................................................ 1

2 Normative references ................................................................................................................................ 1

3 Terms and definitions ................................................................................................................................ 1

4 Principle ......................................................................................................................................................... 1

5 Apparatus ....................................................................................................................................................... 2

6 Adhesives ....................................................................................................................................................... 4

7 Sampling ......................................................................................................................................................... 5

8 Test panels ..................................................................................................................................................... 5

8.1 Substrate ........................................................................................................................................................ 5

8.2 Preparation and coating ............................................................................................................................ 5

8.3 Drying and conditioning............................................................................................................................ 5

8.4 Thickness of coating ................................................................................................................................... 5

9 Procedure ...................................................................................................................................................... 5

9.1 Number of determinations ....................................................................................................................... 5

9.2 Ambient conditions ..................................................................................................................................... 5

9.3 Adhesive ......................................................................................................................................................... 5

9.4 Test assemblies ............................................................................................................................................ 6

9.4.1 Method A: General method (using two dollies) for testing both rigid and deformable

substrates....................................................................................................................................................... 6

9.4.2 Method B: Method for testing from one side only, using a single dolly (suitable for

rigid substrates only) ................................................................................................................................. 6

9.4.3 Method C: Method using dollies, one as a painted substrate ......................................................... 7

9.5 Measurement ................................................................................................................................................ 8

9.5.1 Breaking strength ........................................................................................................................................ 8

9.5.2 Nature of the fracture ................................................................................................................................. 8

10 Calculation and expression of results ................................................................................................... 8

10.1 Breaking strength ........................................................................................................................................ 8

10.2 Nature of failure ........................................................................................................................................... 9

10.3 Example .......................................................................................................................................................... 9

11 Precision ......................................................................................................................................................... 9

12 Test report ..................................................................................................................................................... 9

Bibliography ............................................................................................................................................................. 11

Foreword ..................................................................................................................................................................... iv

Introduction ................................................................................................................................................................. v

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2 Normative references ................................................................................................................................. 1

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3 Terms and definitions ................................................................................................................................ 1 Formatted: Font: 11.5 pt, Font color: Custom

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4 Principle ......................................................................................................................................................... 2

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5 Apparatus ....................................................................................................................................................... 2

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6 Adhesives ....................................................................................................................................................... 6

7 Sampling ......................................................................................................................................................... 7

8 Test panels ..................................................................................................................................................... 7

8.1 Substrate ........................................................................................................................................................ 7

8.2 Preparation and coating ............................................................................................................................ 7

8.3 Drying and conditioning ............................................................................................................................ 7

8.4 Thickness of coating ................................................................................................................................... 7

9 Procedure ....................................................................................................................................................... 7

9.1 Number of determinations ....................................................................................................................... 7

9.2 Ambient conditions ..................................................................................................................................... 7

9.3 Adhesive ......................................................................................................................................................... 8

9.4 Test assemblies ............................................................................................................................................ 8

9.4.1 Method A: General method (using two dollies) for testing both rigid and deformable

substrates ....................................................................................................................................................... 8

9.4.2 Method B: Method for testing from one side only, using a single dolly (suitable for

rigid substrates only) ................................................................................................................................. 9

9.4.3 Method C: Method using dollies, one as a painted substrate ....................................................... 10

9.5 Measurement .............................................................................................................................................. 11

9.5.1 Breaking strength ...................................................................................................................................... 11

9.5.2 Nature of the fracture ............................................................................................................................... 12

10 Calculation and expression of results ................................................................................................. 12

10.1 Breaking strength ...................................................................................................................................... 12

10.2 Nature of failure ......................................................................................................................................... 12

10.3 Example ........................................................................................................................................................ 13

11 Precision ....................................................................................................................................................... 13

12 Test report ................................................................................................................................................... 13

Bibliography .............................................................................................................................................................. 15

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ISO/DIS FDIS 4624:20222023(E)
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Foreword Formatted: Font: 11.5 pt, Font color: Custom
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ISO (the International Organization for Standardization) is a worldwide federation of national Formatted: Space After: 0 pt, Line spacing: single

standards bodies (ISO member bodies). The work of preparing International Standards is normally

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carried out through ISO technical committees. Each member body interested in a subject for which a

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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

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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/directiveswww.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, in collaboration with the European Committee for Formatted: English (United Kingdom)

Standardization (CEN) Technical Committee CEN/TC 139 Paints and varnishes, in accordance with the

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Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
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This fourth edition cancels and replaces the third edition (ISO 4624:2016), which has been technically

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revised.
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The main changes are as follows:
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— Clause 3 on terms and definitions has been added;
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— for the use of this method on concrete, larger dolly of up to 100 mm arehave been added to 5.2;

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— requirement concerning the adhesive in relation to substrate or coating material has been added in Formatted: Pattern: Clear

Clause 6 (last sentence).
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— additional information has been added to the single dolly method in 9.4.2;
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— the text has been editorially revised and — the normative references have been updated.

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Any feedback or questions on this document should be directed to the user’s national standards body. A

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complete listing of these bodies can be found at
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www.iso.org/members.htmlwww.iso.org/members.html.
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Introduction Color(RGB(33;29;30))
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This document describes methods for assessing the adhesion of a single coating or a multi-coat system

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of paint, varnish or related product by measuring the minimum tensile stress necessary to detach or to

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rupture the coating in a direction perpendicular to the substrate.

The test result is influenced not only by the mechanical properties of the system under test, but also by

the nature and preparation of the substrate, the method of paint application, the drying conditions of

the coating, the temperature, the humidity and other factors like the type of test instrument which has

been used.
ISO 2409 can also be used for the evaluation of adhesion characteristics.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 4624:2023(E)
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page header
Paints and varnishes — Pull-off test for adhesion
1 Scope Formatted: Tab stops: Not at 21.6 pt

This document specifies three methods for determining the adhesion by carrying out a pull-off test on a

single coating or a multi-coat system of paint, varnish or related product.
These methods include:

- Method— method A: using two dollies, suitable for testing both rigid and deformable substrates;

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39.7 pt, Left + 59.55 pt, Left + 79.4 pt, Left + 99.25 pt,

- Method— method B: testing from one side only, using a single dolly, suitable for rigid substrates only;

Left + 119.05 pt, Left + 138.9 pt, Left + 158.75 pt, Left
+ 178.6 pt, Left + 198.45 pt, Left
- Method— method C: using dollies, one as a painted substrate.

These test methods have been found useful in comparing the adhesion behaviour of different coatings.

It is most useful in providing relative ratings for a series of coated panels exhibiting significant

differences in adhesion.

The test can be applied using a wide range of substrates. Different procedures are given according to

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whether the substrate is deformable, for examplee.g. thin metal, plastics and wood, or rigid, for

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examplee.g. thick concrete and metal plates. To avoid distortion of the substrate during the tensile test,

it is common to use a sandwich construction. For example, for special purposes, the coating can be Formatted: Pattern: Clear

applied directly to the face of a test dolly.
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2 Normative references
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The following documents are referred to in the text in such a way that some or all of their content Formatted: Pattern: Clear

constitutes requirements of this document. For dated references, only the edition cited applies. For

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undated references, the latest edition of the referenced document (including any amendments) applies.

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ISO 1513, Paints and varnishes — Examination and preparation of test samples
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ISO 1514, Paints and varnishes — Standard panels for testing
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ISO 2808, Paints and varnishes — Determination of film thickness
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ISO 3270, Paints and varnishes and their raw materials — Temperatures and humidities for conditioning Formatted: Pattern: Clear

and testing
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ISO 4618, Paints and varnishes— Terms and definitions
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ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling

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3 Terms and definitions
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For the purposes of this document, the terms and definitions given in ISO 4618 apply.

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ISO/FDIS 4624:2023(E)

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/

4 Principle
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The product or system under test is applied at uniform thickness to flat panels of uniform surface

texture.

After drying/curing the coating system, dollies are bonded directly to the surface of the coated, and

cured panel using an adhesive.

After curing the adhesive, the bonded dolly assemblies are placed in a suitable tensile tester. The

bonded assemblies are subjected to a controlled tensile test (pull-off test), and the force required to

break the coating/substrate bond is measured.

To avoid possible distortion of the substrate during the tensile test, dollies with a diameter smaller than

the 2 cm diameter used for steel substrates may be used to reduce the force introduced.

The test result is the tensile stress necessary to break the weakest interface (adhesive failure) or the

weakest component (cohesive failure) of the test assembly. Mixed adhesive/cohesive failures may also

occur.
5 Apparatus
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5.1 Tensile tester, suitable for carrying out the chosen procedure specified in Clause 9. The tensile

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stress shall be applied in a direction perpendicular to the plane of the coated substrate and shall be

increased at a substantially uniform rate, not greater than 1 MPa/s such that failure of the test

assembly occurs within 90 s. Suitable designs for applying the tensile stress are shown in Figures 1

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and 2.

Instead of a tensile tester, other types of pull-off adhesion testers (mechanically, pneumatically,

hydraulically or hand-driven) may be used provided that they give similar results. The type of

instrument shall be reported in the test report, because hand-driven/mechanical/hydraulic

instruments are reported to produce widely different results.

NOTE The results can be influenced by the test assembly used. Furthermore, the results are not reproducible

unless coaxial alignment of the tensile forces is ensured.
1 MPa/s = 1 MN/(m ·s).
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ISO/FDIS 4624:2023(E)
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Key
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1 support
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ISO/FDIS 4624:2023(E)
2 ball joint
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3 dollies
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4 coating
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5 substrate

NOTE These methods are described in 9.4.1 and 9.4.3. Formatted: Don't keep with next

NOTE These methods are described in 9.4.1 and 9.4.3.

Figure 1 — Example of a suitable test apparatus for the two-dolly methods (methods A and C)

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ISO/FDIS 4624:2023(E)
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1 coating
keep with next
2 test piece
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3 dolly
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4 ball-and-socket sliding joint
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5 support (suitably designed to allow for joint assembly)
6 ball-and-socket sliding joint
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NOTE This test apparatus is described in 9.4.2.
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NOTE This test apparatus is described in 9.4.2.
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Figure 2 — Example of a suitable test apparatus for the one-dolly method (method B)

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5.2 Test dollies, each consisting of a steel or aluminium cylindrical-faced testing body, specifically

designed to be used with the tensile tester. Each dolly has a rigid, flat face for bonding the

adhesive/coating at one end and a facility for connecting the pull-off tester at the other. Each dolly has a

nominal diameter of 20 mm and sufficient thickness to ensure freedom from distortion during the test.

It is recommended that the length of each doll
...

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 4624
ISO/TC 35/SC 9
Paints and varnishes — Pull-off test
Secretariat: BSI
for adhesion
Voting begins on:
2023-03-01
Peintures et vernis — Essai de traction
Voting terminates on:
2023-04-26
ISO/CEN PARALLEL PROCESSING
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 4624:2023(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 1 ----------------------
ISO/FDIS 4624:2023(E)
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 4624
ISO/TC 35/SC 9
Paints and varnishes — Pull-off test
Secretariat: BSI
for adhesion
Voting begins on:
Peintures et vernis — Essai de traction
Voting terminates on:
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All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may

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or ISO’s member body in the country of the requester.
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BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
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LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
Published in Switzerland
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN­
DARDS TO WHICH REFERENCE MAY BE MADE IN
© ISO 2023 – All rights reserved
NATIONAL REGULATIONS. © ISO 2023
---------------------- Page: 2 ----------------------
ISO/FDIS 4624:2023(E)
Contents Page

Foreword ........................................................................................................................................................................................................................................iv

Introduction .................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ..................................................................................................................................................................................... 1

3 Terms and definitions .................................................................................................................................................................................... 1

4 Principle ........................................................................................................................................................................................................................ 2

5 Apparatus .................................................................................................................................................................................................................... 2

6 Adhesives ..................................................................................................................................................................................................................... 5

7 Sampling ....................................................................................................................................................................................................................... 6

8 Test panels ..................................................................................................................................................................................................................6

8.1 Substrate ...................................................................................................................................................................................................... 6

8.2 Preparation and coating ................................................................................................................................................................ 6

8.3 Drying and conditioning ................................................................................................................................................................ 6

8.4 Thickness of coating .......................................................................................................................................................................... 6

9 Procedure ....................................................................................................................................................................................................................6

9.1 Number of determinations .......................................................................................................................................................... 6

9.2 Ambient conditions............................................................................................................................................................................. 6

9.3 Adhesive ....................................................................................................................................................................................................... 6

9.4 Test assemblies ....................................................................................................................................................................................... 7

9.4.1 Method A: General method (using two dollies) for testing both rigid and

deformable substrates .................................................................................................................................................. 7

9.4.2 Method B: Method for testing from one side only, using a single dolly

(suitable for rigid substrates only) .................................................................................................................... 7

9.4.3 Method C: Method using dollies, one as a painted substrate ...................................................... 8

9.5 Measurement ........................................................................................................................................................................................... 9

9.5.1 Breaking strength ............................................................................................................................................................. 9

9.5.2 Nature of the fracture .................................................................................................................................................... 9

10 Calculation and expression of results ........................................................................................................................................... 9

10.1 Breaking strength ............................................................................................................................................................................... 9

10.2 Nature of failure ................................................................................................................................................................................. 10

10.3 Example ..................................................................................................................................................................................................... 10

11 Precision ....................................................................................................................................................................................................................10

12 Test report ...............................................................................................................................................................................................................10

Bibliography .............................................................................................................................................................................................................................12

iii
© ISO 2023 – All rights reserved
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ISO/FDIS 4624:2023(E)
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 non­governmental, 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, in collaboration with the European Committee for

Standardization (CEN) Technical Committee CEN/TC 139 Paints and varnishes, in accordance with the

Agreement on technical cooperation between ISO and CEN (Vienna Agreement).

This fourth edition cancels and replaces the third edition (ISO 4624:2016), which has been technically

revised.
The main changes are as follows:
— Clause 3 on terms and definitions has been added;

— for the use of this method on concrete, larger dolly of up to 100 mm have been added to 5.2;

— requirement concerning the adhesive in relation to substrate or coating material has been added in

Clause 6 (last sentence).
— additional information has been added to the single dolly method in 9.4.2;
— the normative references have been updated.

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.
© ISO 2023 – All rights reserved
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ISO/FDIS 4624:2023(E)
Introduction

This document describes methods for assessing the adhesion of a single coating or a multi-coat system

of paint, varnish or related product by measuring the minimum tensile stress necessary to detach or to

rupture the coating in a direction perpendicular to the substrate.

The test result is influenced not only by the mechanical properties of the system under test, but also by

the nature and preparation of the substrate, the method of paint application, the drying conditions of

the coating, the temperature, the humidity and other factors like the type of test instrument which has

been used.
ISO 2409 can also be used for the evaluation of adhesion characteristics.
© ISO 2023 – All rights reserved
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 4624:2023(E)
Paints and varnishes — Pull-off test for adhesion
1 Scope

This document specifies three methods for determining the adhesion by carrying out a pull-off test on a

single coating or a multi-coat system of paint, varnish or related product.
These methods include:

— method A: using two dollies, suitable for testing both rigid and deformable substrates;

— method B: testing from one side only, using a single dolly, suitable for rigid substrates only;

— method C: using dollies, one as a painted substrate.

These test methods have been found useful in comparing the adhesion behaviour of different coatings.

It is most useful in providing relative ratings for a series of coated panels exhibiting significant

differences in adhesion.

The test can be applied using a wide range of substrates. Different procedures are given according to

whether the substrate is deformable, e.g. thin metal, plastics and wood, or rigid, e.g. thick concrete and

metal plates. To avoid distortion of the substrate during the tensile test, it is common to use a sandwich

construction. For example, for special purposes, the coating can be applied directly to the face of a test

dolly.
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 1513, Paints and varnishes — Examination and preparation of test samples
ISO 1514, Paints and varnishes — Standard panels for testing
ISO 2808, Paints and varnishes — Determination of film thickness

ISO 3270, Paints and varnishes and their raw materials — Temperatures and humidities for conditioning

and testing
ISO 4618, Paints and varnishes— Terms and definitions

ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 4618 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 2023 – All rights reserved
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ISO/FDIS 4624:2023(E)
4 Principle

The product or system under test is applied at uniform thickness to flat panels of uniform surface

texture.

After drying/curing the coating system, dollies are bonded directly to the surface of the coated and

cured panel using an adhesive.

After curing the adhesive, the bonded dolly assemblies are placed in a suitable tensile tester. The bonded

assemblies are subjected to a controlled tensile test (pull-off test), and the force required to break the

coating/substrate bond is measured.

To avoid possible distortion of the substrate during the tensile test, dollies with a diameter smaller

than the 2 cm diameter used for steel substrates may be used to reduce the force introduced.

The test result is the tensile stress necessary to break the weakest interface (adhes

...