ISO/FDIS 11998

• Abstract:

  The ability of coatings to withstand wear caused by repeated cleaning operations and to withstand penetration by soiling agents is an important consideration both from a practical point of view and when comparing and rating such coatings. ISO 11998:2006 describes an accelerated method for the determination of wet-scrub resistance. With regard to the cleanability of coatings, only the method itself and not the soiling agents are specified.

• 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/WG 31 - Properties after application
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 08-Jul-2026
• Completion Date: 08-Jul-2026

• Consolidates: FprEN ISO 11998 - Paints and varnishes - Determination of wet-scrub resistance of coatings (ISO/FDIS 11998:2026)
• Effective Date: 12-Feb-2026
• Revises: ISO 11998:2006 - Paints and varnishes — Determination of wet-scrub resistance and cleanability of coatings
• Effective Date: 15-Jun-2024

Overview

ISO/FDIS 11998:2026 - Paints and Varnishes: Determination of Wet-Scrub Resistance of Coatings is an international standard developed by ISO for assessing the durability of paint and varnish coatings under repeated wet cleaning (wet-scrub) conditions. This standard defines an accelerated laboratory method to measure the wet-scrub resistance of surface coatings by subjecting coated panels to controlled mechanical scrubbing. Wet-scrub resistance is an essential property for coatings used in areas subject to frequent cleaning or contamination, helping manufacturers, specifiers, and end-users objectively compare and classify products for real-world durability.

Key Topics

• Wet-Scrub Resistance
  The ability of a dry coating film to endure repeated scrubbing with a defined washing liquid and abrasive pad, quantified by measuring loss in film thickness or mass after a specified number of cycles.

• Test Methodology

  • Application of the coating on a defined substrate using a standardized film applicator
  • Conditioning and drying under controlled climate conditions
  • Mechanical scrubbing using a specified apparatus, abrasive pad, and washing liquid
  • Measurement of coating loss in mass or thickness to determine resistance class

• Apparatus and Materials

  • Scrub tester with reciprocating mechanism
  • Technical non-woven abrasive pads, subject to batch quality control
  • Polyvinyl chloride (PVC) film or equivalent substrates
  • Standard washing liquid and precision balance

• Reporting and Classification

  • Calculation and reporting of coating loss per area or thickness
  • Assignment to wet-scrub resistance classes as agreed by involved parties or referencing classification systems (such as EN 13300)

• Quality Control and Repeatability
  Enhanced accuracy requirements for weighing and strict control of test consumables, including batch and reference checks for abrasives.

Applications

ISO 11998:2026 is widely applicable to the paints and coatings industry for research, quality control, and product certification. Typical uses include:

• Product Comparison
  Enables manufacturers and specifiers to objectively compare the wet-scrub durability of products such as interior wall paints, varnishes, and topcoats.

• Performance Classification
  Supports classification according to national or international frameworks, informing product labeling and compliance (e.g., EN 13300 for interior wall paints).

• Quality Assurance and Product Development
  Assists in the formulation of coatings with improved resistance to cleaning - valuable for surfaces in hospitals, schools, kitchens, and public spaces.

• Regulatory and Contractual Requirements
  Demonstrates conformity to technical performance standards in procurement, project specifications, and legal compliance.

Related Standards

For comprehensive assessment and testing of paints and varnishes, the following standards are often referenced alongside ISO/FDIS 11998:

• ISO 1513: Paints and varnishes - Examination and preparation of test samples
• ISO 3696: Water for analytical laboratory use - Specification and test methods
• ISO 4618: Paints and varnishes - Vocabulary
• ISO 15528: Sampling of paints, varnishes, and raw materials
• ISO 5725-2: Accuracy (trueness and precision) of measurement methods and results

Practical Value

Implementing ISO/FDIS 11998 enables manufacturers to demonstrate the cleaning durability of their coatings, improve consistency, and reduce product failures. Facility managers and specifiers can make informed choices for high-traffic, frequently-cleaned environments. By standardizing the determination of wet-scrub resistance, this ISO standard underpins trust and comparability in the performance claims of paints and varnishes globally.

Keywords: ISO 11998, wet-scrub resistance, paint testing, coating durability, cleaning resistance, quality control, coatings industry, standard method, paints and varnishes, laboratory testing.

FINAL DRAFT
International
Standard
ISO/TC 35/SC 9
Paints and varnishes —
Secretariat: BSI
Determination of wet-scrub
Voting begins on:
resistance of coatings
2026-07-08
Peintures et vernis — Détermination de la résistance au
Voting terminates on:
frottement humide des revêtements
2026-09-02
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
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/CEN PARALLEL PROCESSING 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.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 35/SC 9
Paints and varnishes —
Secretariat: BSI
Determination of wet-scrub
Voting begins on:
resistance of coatings
Peintures et vernis — Détermination de la résistance au
Voting terminates on:
frottement humide des revêtements
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.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
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 Reference number
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents . 2
6 Apparatus . 2
7 Sampling . 4
8 Procedure . 4
8.1 Film application .4
8.2 Wet-scrub resistance .4
9 Expression of results . 6
9.1 Calculation of the loss in coating mass per unit area .6
9.1.1 Area traversed by the scrub pad .6
9.1.2 Loss in coating mass per unit area .6
9.2 Calculation of mean loss in film thickness .6
9.3 Assessment of wet-scrub resistance .7
10 Precision . 7
10.1 General .7
10.2 Repeatability .7
10.3 Reproducibility . .7
11 Test report . 7
Annex A (normative) Determination of dry-film density of the coating . 8
Annex B (normative) Quality control of the non-woven abrasive .10
Annex C (normative) Acceptance of new non-woven abrasive .11
Annex D (normative) Preparation and formulation of reference paint .12
Annex E (informative) Example of reference paint . 14
Annex F (informative) Details on interlaboratory comparison .16
Bibliography . 17

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
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 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, 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 third edition cancels and replaces the second edition (ISO 11998:2006), which has been technically
revised.
The main changes are as follows:
— the title has been changed to “Determination of wet-scrub resistance of coatings”;
— the introduction has been deleted;
— cleanability has been deleted completely;
— weighing accuracy has been changed from 1 mg to 0,1 mg;
— the description of the abrasive pad has been clarified;
— five new Annexes B to F have been added;
— a batch control of the non-woven abrasive has been introduced in Annex B;
— criteria for the acceptance of new non-woven abrasive have been introduced in Annex C;
— preparation and formulation of a general reference paint have been introduced in Annex D;
— preparation and formulation of an example reference paint have been introduced in Annex E;
— details on the interlaboratory comparison have been introduced in Annex F;
— the statistical data on reproducibility and repeatability have been updated.

iv
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.

v
FINAL DRAFT International Standard ISO/FDIS 11998:2026(en)
Paints and varnishes — Determination of wet-scrub
resistance of coatings
1 Scope
This document specifies an accelerated method for the determination of wet-scrub resistance. The
determination of cleanability is not covered in the scope of this document.
NOTE The ability of coatings to withstand wear caused by repeated cleaning operations is an important
consideration both from a practical point of view and when comparing and rating such coatings. Since wet-scrub
resistance depends not only on the quality of a coating but also on the substrate, the method of application, the drying
conditions and other factors, the results obtained are not directly transferable to actual practice. In this document,
the evaluation of the coating is based on a defined substrate, a fixed application method, specified drying conditions
and a defined method of wet scrubbing.
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 3696, Water for analytical laboratory use — Specification and test methods
ISO 4618, Paints and varnishes — Vocabulary
ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method for
the determination of repeatability and reproducibility of a standard measurement method
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 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
scrub cycle
one reciprocal movement of the scrub pad over the scrub length (3.2) in both directions
3.2
scrub length
stroke length (3.3) plus the length of the pad
3.3
stroke length
distance traversed by one stroke of the apparatus

3.4
wet-scrub resistance
ability of a dry coating film to sustain less than a specified loss in film thickness, averaged over a defined
area, when exposed to a defined number of wet-scrub cycles
4 Principle
The test coating is applied to a test panel using a film applicator at the appropriate gap clearance. After
drying and conditioning, the coated panel is weighed and subjected to a defined number of wet-scrub cycles
in a scrub testing machine as described in 8.2.
NOTE Some classification standards, e.g. EN 13300, require fewer scrub cycles.
It is then washed, dried and weighed again to determine its loss in mass, from which the mean loss in film
thickness is calculated.
Through comparison of the mean loss in film thickness with a specified value, as agreed between interested
parties, the coating can be rated in wet-scrub resistance classes.
5 Reagents
5.1 Washing liquid. Use a 2,5 g/l solution of sodium n-dodecylbenzenesulfonate (CAS Registry Number
®1)
25155-30-0) in water conforming to the requirements of grade 3 of ISO 3696. Allow the solution to stand
before use until all air-bubbles and foam have dissipated.
6 Apparatus
6.1 Test panel, made of polyvinyl chloride (PVC) film free of migration-susceptible chemical plasticizers,
of sufficient rigidity to ensure a flat surface, impervious to and unaffected by water or aliphatic organic
solvents and of a nominal thickness of 0,25 mm, approximately 430 mm long and not less than 80 mm wide.
Other types of film may be used where the coating contains solvent, which can adversely affect the PVC film,
e.g. a metal alloy with a thickness of about 0,25 mm. If the coating delaminates before or during the test,
another more suitable substrate shall be used.
6.2 Film applicator, preferably an automatic film applicator, used at an application speed of 10 mm/s to
15 mm/s and fitted with a doctor blade with an appropriate gap clearance and a gap width of at least 60 mm.
6.3 Wet-scrub tester apparatus, consisting of a reciprocating scrub testing machine with a stroke length
of (300 ± 10) mm and operating at approximately (37 ± 2) scrub cycles per minute. A counter for recording
the number of scrub cycles shall be provided.
6.4 Scrub pad holder, consisting of a metal plate fitted with pins to hold the abrasive pad. A mounting
device with elongated holes is loosely fitted on the top of the plate (see Figure 1 and Figure 2). Alternatively,
other scrub pad holders, e.g. with hook-and-loop fastener, can be used. The mass of the scrub pad holder,
which exerts a downward force on the test panel shall be (135 ± 1) g.

1) CAS Registry Number® is a trademark of the American Chemical Society (ACS). This information is given for the
convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent
products may be used if they can be shown to lead to the same results.

Figure 1 — Mounting device
Dimensions in millimetres
Key
1 pins
Figure 2 — Scrub pad holder
6.5 Technical non-woven abrasive, a non-woven pad, consisting of a plastics material, with embedded
abrasive, measuring (90,0 ± 0,5) mm × (39,0 ± 0,5) mm. A new abrasive pad shall be used for every test.
2) 3)
TM TM
NOTE Scotch-Brite 7448+ Vlies and Abraflex E-Type S-1200 Vlies have proven to be suitable.
Since the quality of the technical non-woven abrasive has a direct impact on the test result, batch control of
suitable technical non-woven pads is required. The quality of each batch shall be proven in accordance with
Annex B.
2) Scotch-Brite 7448+ Vlies is the trade name of a product supplied by 3M. This information is given for the convenience
of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may
be used if they can be shown to lead to the same results.
3) Abraflex E-Type S-1200 Vlies is the trade name of a product supplied by JÖST abrasives GmbH. This information is
given for the convenience of users of this document and does not constitute an endorsement by ISO of the product named.
Equivalent products may be used if they can be shown to lead to the same results.

New technical non-woven abrasives shall be proven in accordance with Annex C in an interlaboratory
comparison.
A reference paint shall be chosen in accordance with Annex D for testing purposes of the non-woven abrasive.
6.6 Analytical balance, shielded from draughts, capable of weighing the test panel with applied coating
to the nearest 0,1 mg.
6.7 Straight-edge ruler, with 0,5 mm divisions.
7 Sampling
Take a representative sample of the coating to be tested, as specified in ISO 15528.
Examine and prepare the sample as specified in ISO 1513.
8 Procedure
8.1 Film application
Using the film applicator, make a draw-down of the prepared sample of coating material on the plastics film
to achieve an even film at least 10 mm longer than the scrub length. Prepare one or more coated plastics
film to be able to create enough test panels for threefold testing according to 8.2. Cut the coated plastics
film(s) in three stripes according to dimension requirements given in 6.1 and 6.3. Ensure the gap clearance
is sufficient so that the resulting dry film is of such a thickness that, after the defined number of wet-scrub
cycles, the substrate is not exposed.
If no film applicator is used, apply the sample of coating material in accordance with the industrial application
method recommended by the technical data sheet of the coating system to be tested.
For the determination of wet-scrub resistance, dry the film at a temperature of (23 ± 2) °C and a relative
humidity of (50 ± 5) % according to ISO 3270 for the required period. The drying time is specified by the
customer on the basis of classification standards, legal requirements or technical soundness and shall be
recorded during the test procedure.
Weigh the test panel with the dried coating film to the nearest 0,1 mg.
NOTE 1 Duplicate panels are best prepared by using a standard
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ISO/TC 35/SC 9
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Secretariat: BSI
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Date: 2026-01-2006-24
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Paints and varnishes — Determination of wet-scrub resistance of
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St l D fi iti
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All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
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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
Formatted: Right: 1.5 cm, Bottom: 1 cm, Gutter: 0 cm,
at the address below or ISO’s member body in the country of the requester.
Header distance from edge: 1.27 cm, Footer distance
from edge: 0.5 cm
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
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ii
ISO/DISFDIS 11998:20252026(en) Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Contents
Formatted: Font: Bold
Formatted: HeaderCentered, Left
Foreword . v
Formatted: Adjust space between Latin and Asian text,
1 Scope . 1
Adjust space between Asian text and numbers
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents . 2
6 Apparatus . 2
7 Sampling . 5
8 Procedure . 5
8.1 Film application . 5
8.2 Wet-scrub resistance . 6
9 Expression of results . 9
9.1 Calculation of the loss in coating mass per unit area . 9
9.2 Calculation of mean loss in film thickness . 9
9.3 Assessment of wet-scrub resistance . 10
10 Precision . 10
10.1 General. 10
10.2 Repeatability . 10
10.3 Reproducibility . 10
11 Test report . 10
Annex A (normative) Determination of dry-film density of the coating . 12
Annex B (normative) Quality control of the non-woven abrasive. 16
Annex C (normative) Acceptance of new non-woven abrasive . 17
Annex D (normative) Preparation and formulation of reference paint . 18
Annex E (informative) Example of reference paint . 20
Annex F (informative) Details on interlaboratory comparison . 22
Bibliography . 23

Foreword . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
Formatted: Font: 10 pt
5 Reagents . 2
Formatted: Font: 10 pt
6 Apparatus . 2
Formatted: FooterCentered, Left, Space Before: 0 pt,
1 pins . 3
Tab stops: Not at 17.2 cm
7 Sampling . 4 Formatted: Font: 11 pt
Formatted: FooterPageRomanNumber, Left, Space
8 Procedure . 4
After: 0 pt, Tab stops: Not at 17.2 cm
iii
Formatted: Font: Bold
Formatted: HeaderCentered
8.1 Film application . 4
8.2 Wet-scrub resistance . 4
9 Expression of results . 6
9.1 Calculation of the loss in coating mass per unit area . 6
9.1.1 Area traversed by the scrub pad . 6
9.1.2 Loss in coating mass per unit area. 7
9.2 Calculation of mean loss in film thickness . 7
9.3 Assessment of wet-scrub resistance . 7
10 Precision . 7
10.1 General. 7
10.2 Repeatability . 7
10.3 Reproducibility . 7
11 Test report . 8
Annex A (normative) Determination of dry-film density of the coating . 9
A.1 General. 9
A.2 Preparation of the test coating . 9
A.3 Cutting out test pieces . 9
A.4 Procedure . 9
A.5 Calculation of the dry-film density . 10
Annex B (normative) Quality control of the non-woven abrasive . 11
B.1 General. 11
B.2 Measuring reference paint . 11
Annex C (normative) Acceptance of new non-woven abrasive . 12
C.1 General. 12
C.2 Measuring reference paints . 12
Annex D (normative) Preparation and formulation of reference paint . 13
D.1 General. 13
D.2 Reference paint preparation and formulation . 13
Annex E (informative) Details on interlaboratory comparison . 15
E.1 General. 15
E.2 Sample . 15
E.3 Non-woven abrasive . 15
E.4 Determination of dry-film density . 15
E.5 Determination of wet-scrub resistance . 15
E.6 Statistic . 15
Formatted: FooterPageRomanNumber
iv
ISO/DISFDIS 11998:20252026(en) Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Foreword
Formatted: Font: Bold
ISO (the International Organization for Standardization) is a worldwide federation of national standards Formatted: HeaderCentered, Left
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
Formatted: Adjust space between Latin and Asian text,
ISO technical committees. Each member body interested in a subject for which a technical committee has been
Adjust space between Asian text and numbers
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 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).
Formatted: English (United Kingdom)
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.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.htmlwww.iso.org/iso/foreword.html.
Formatted: English (United Kingdom)
This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee SC 9,
Formatted: Adjust space between Latin and Asian text,
General test methods for paints and varnishes, in collaboration with the European Committee for
Adjust space between Asian text and numbers
Standardization (CEN) Technical Committee CEN/TC 139, Paints and varnishes, in accordance with the
Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
Formatted: Default Paragraph Font
This third edition cancels and replaces the second edition (ISO 11998:2006), which has been technically
Formatted: Default Paragraph Font
revised.
Formatted: Default Paragraph Font
The main changes are as follows:
Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers, Tab
— — the title has been changed to “Determination of wet-scrub resistance of coatings”;
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
— — the introduction has been deleted;
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Adjust space between Asian text and numbers, Tab
— — cleanability has been deleted completely;
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
— — weighing accuracy has been changed from 1 mg to 0,1 mg;
Formatted: Font: 10 pt
— the description of the abrasive pad has been clarified, and ;
Formatted: Font: 10 pt
— five new Annexes B to F have been added; Formatted: FooterCentered, Left, Space Before: 0 pt,
Tab stops: Not at 17.2 cm
— a qualitybatch control of the non-woven abrasive has been introduced in Annex B;
Formatted: Font: 11 pt
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— weighing accuracy have been changed from 1 mg to 0,1 mg;
After: 0 pt, Tab stops: Not at 17.2 cm
v
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— five new annexes (B to F) have been added;
— — criteria for the acceptance of new non-woven abrasive have been introduced in Annex C;
— preparation and formulation of a general reference paint have been introduced in Annex D;
— preparation and formulation of an example reference paint have been introduced in Annex E;
— details on the interlaboratory comparison have been introduced in Annex F;
— the statistical data on reproducibility and repeatability 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
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
complete listing of these bodies can be found at www.iso.org/members.html.
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Formatted: English (United Kingdom)

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Field Code Changed
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vi
DRAFT International Standard ISO/DIS 11998:2025(en)

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Formatted: Main Title 1, Space After: 0 pt, Adjust
Paints and varnishes — Determination of wet-scrub resistance of
space between Latin and Asian text, Adjust space
coatings
between Asian text and numbers
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1 Scope
Header distance from edge: 1.27 cm, Footer distance
from edge: 0.5 cm
This document specifies an accelerated method for the determination of wet-scrub resistance. The
determination of cleanability is not covered in the scope of this document.
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...
NOTE The ability of coatings to withstand wear caused by repeated cleaning operations is an important
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...
consideration both from a practical point of view and when comparing and rating such coatings. Since wet-scrub
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...
resistance depends not only on the quality of a coating but also on the substrate, the method of application, the drying
conditions and other factors, the results obtained are not directly transferable to actual practice. In this document, the
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evaluation of the coating is based on a defined substrate, a fixed application method, specified drying conditions and a
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defined method of wet scrubbing.
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2 Normative references
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...
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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, Formatted: Default Paragraph Font
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 3696, Water for analytical laboratory use — Specification and test methods
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ISO 4618, Paints and varnishes — Vocabulary
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ISO 5725--2, Accuracy (trueness and precision) of measurement methods and results — Part 2: Basic method
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for the determination of repeatability and reproducibility of a standard measurement method
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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 and the following apply.
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ISO and IEC maintain terminology databases for use in standardization at the following addresses:
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— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
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— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
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Formatted: English (United Kingdom)
3.1 3.1
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scrub cycle
...
one reciprocal movement of the scrub pad over the scrub length (3.2)(3.2) in both directions
Formatted: English (United Kingdom)
Formatted: English (United Kingdom)
3.2 3.2
scrub length Formatted: Font: Cambria, English (United Kingdom)
stroke length (3.3)(3.3) plus the length of the pad
Formatted
...
Formatted
...
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3.3 3.3
stroke length
distance traversed by one stroke of the apparatus
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3.4 3.4
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wet--scrub resistance
ability of a dry coating film to sustain less than a specified loss in film thickness, averaged over a defined area, Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers, Tab
when exposed to a defined number of wet--scrub cycles
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
4 Principle
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The test coating is applied to a test panel using a film applicator at the appropriate gap clearance. After drying
and conditioning, the coated panel is weighed and subjected to a defined number of wet--scrub cycles in a
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scrub testing machine as described in 8.2.8.2.
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NOTE Some classification standards, e.g. EN 13300, require fewer scrub cycles.
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It is then washed, dried and weighed again to determine its loss in mass, from which the mean loss in film
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thickness is calculated.
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Through comparison of the mean loss in film thickness with a specified value, as agreed between interested
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parties, the coating can be rated in wet--scrub resistance classes.
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Bold
5 Reagents
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5.1 5.1 Washing liquid. Use a 2,5 g/l solution of sodium n--dodecylbenzenesulfonate (CAS- Registry
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®11)
Number 25155-30-0) in water conforming to the requirements of grade 3 of ISO 3696. Allow the solution
Bold
to stand before use until all air--bubbles and foam have dissipated.
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6 Apparatus
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6.1 6.1 Test panel, made of polyvinyl chloride (PVC) film free of migration--susceptible chemical
plasticizers, of sufficient rigidity to ensure a flat surface, impervious to and unaffected by water or aliphatic
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organic solvents and of a nominal thickness of 0,25 mm, approximately 430 mm long and not less than 80 mm Adjust space between Asian text and numbers
wide.
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Other types of film may be used where the coating contains solvent, which can adversely affect the PVC film,
e.g. a metal alloy with a thickness of about 0,25 mm. If the coating delaminates before or during the test,
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another, more suitable, substrate shall be used.
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stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
6.2 6.2 Film applicator, preferably an automatic film applicator, used at an application speed of
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
10 mm/s to 15 mm/s and fitted with a doctor blade with an appropriate gap clearance and a gap width of at
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least 60 mm.
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6.3 6.3 Wet--scrub tester apparatus, consisting of a reciprocating scrub testing machine with a
stroke length of (300 ± 10) mm and operating at approximately (37 ± 2) scrub cycles per minute. A counter
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for recording the number of scrub cycles shall be provided.
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stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
CAS Registry Number® is a trademark of the American Chemical Society (ACS). This information is given for the
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent
Formatted: Font: Not Bold
products may be used if they can be shown to lead to the same results.
1)
CAS Registry Number® is a trademark of the American Chemical Society (ACS). This information is given for the Formatted: Font: 11 pt, Not Bold
convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent
Formatted: Font: Not Bold
products may be used if they can be shown to lead to the same results.

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ISO/DISFDIS 11998:20252026(en) Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
6.4 6.4 Scrub pad holder, consisting of a metal plate fitted with pins to hold the abrasive pad. A
Formatted: Font: Bold
mounting device with elongated holes is loosely fitted on the top of the plate (see Figure 1Figure 1 and
Figure 2).Figure 2). Alternatively, other scrub pad holders, e. g. with hook-and-loop fastener, can be used.
Formatted: HeaderCentered, Left
The mass of the scrub pad holder, which exerts a downward force on the test panel shall be (135 ± 1) g.
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Figure 1 — Mounting device
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Asian text, Adjust space between Asian text and
numbers
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Formatted: Font: 10 pt
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Tab stops: Not at 17.2 cm
Formatted: Font: 11 pt
Formatted: FooterPageNumber, Left, Space After: 0 pt,
Tab stops: Not at 17.2 cm
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Dimensions in millimetres
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stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm

Formatted: Key Title, Adjust space between Latin and
Asian text, Adjust space between Asian text and
numbers
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Adjust space between Asian text and numbers, Tab
Key
stops: Not at 0.7 cm + 1.4 cm + 2.8 cm + 3.5 cm +
1 pins
4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Formatted: FooterPageNumber
ISO/DISFDIS 11998:20252026(en) Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Figure 2 — Scrub pad holder
Formatted: Font: Bold
Formatted: HeaderCentered, Left
6.5 6.5 Technical non-woven abrasive, a non--woven pad, consisting of a plastics material, with
embedded abrasive, measuring (90,0 ± 0,5) mm × (39,0 ± 0,5) mm. A new abrasive pad shall be used for every
Formatted: None, Adjust space between Latin and
test.
Asian text, Adjust space between Asian text and
numbers
TM 22) TM 33)
NOTE Scotch-Brite 7448+ Vlies and Abraflex E-Type S-1200 Vlies have proven to be suitable.
Formatted: Font: 11 pt, Not Bold
Formatted: Font: 11 pt, Not Bold
Since the quality of the technical non-woven abrasive has a direct impact on the test result, batch control of
suitable technical non-woven pads is required. The quality of each batch shall be proven according to Annex B.
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.in accordance with Annex B.
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stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
New technical non-woven abrasives shall be proven according to Annex C in ain accordance with Annex C in
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
an interlaboratory comparison.
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6.6 A reference paint shall be chosen in accordance with Annex D for testing purposes of the non-
woven abrasive.
Formatted: English (United Kingdom)
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6.6 Analytical balance, shielded from draughts, capable of weighing the test panel with applied coating
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to the nearest 0,1 mg.
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6.7 6.7 Straight--edge ruler, with 0,5 mm divisions.
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7 Sampling
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Take a representative sample of the coating to be tested, as specified in ISO 15528.
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Examine and prepare the sample as specified in ISO 1513.
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8 Procedure
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8.1 Film application
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Using the film applicator, make a draw--down of the prepared sample of coating material on the plastics film
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to achieve an even film at least 10 mm longer than the scrub length. Prepare one or more coated plastics film
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to be able to create enough test panels for threefold testing according to 8.2.8.2. Cut the coated plastics film(s)
in three stripes according to dimension requirements given in 6.16.1 and 6.3.6.3. Ensure the gap clearance is
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sufficient so that the resulting dry film is of such a thickness that, after the defined number of wet--scrub
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cycles, the substrate is not exposed.
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stops: Not at 0.71 cm
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Adjust space between Asian text and numbers
Scotch-Brite 7448+ Vlies is the trade name of a product supplied by 3M. This information is given for the convenience
Formatted: Default Paragraph Font
of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may
be used if they can be shown to lead to the same results.
2)
Scotch-Brite 7448+ Vlies is the trade name of a product supplied by 3M. This information is given for the convenience
of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may
be used if they can be shown to lead to the same results.
Formatted: Font: 10 pt
Abraflex E-Type S-1200 Vlies is the trade name of a product supplied by JÖST abrasives GmbH. This information is given
Formatted: Font: 10 pt
for the convenience of users of this document and does not constitute an endorsement by ISO of the product named.
Equivalent products may be used if they can be shown to lead to the same results.
Formatted: FooterCentered, Left, Space Before: 0 pt,
3)
Abraflex E-Type S-1200 Vlies is the trade name of a product supplied by JÖST abrasives GmbH. This information is Tab stops: Not at 17.2 cm
given for the convenience of users of this document and does not constitute an endorsement by ISO of the product named.
Formatted: Font: 11 pt
Equivalent products may be used if they can be shown to lead to the same results.

Formatted
...
Formatted: Font: Bold
Formatted: HeaderCentered
If no film applicator is used, apply the sample of coating material in accordance with the industrial application
method recommended by the technical data sheet of the coating system to be tested.
For the determination of wet--scrub resistance, dry the film at a temperature of (23 ± 2) °C and a relative
humidity of (50 ± 5) % according to ISO 3270 for the required period. The drying time is specified by the
customer on the basis of classification standards, legal requirements or technical soundness and shall be
recorded during the test procedure.
Weigh the test panel with the dried coating film to the nearest 0,1 mg.
NOTE 1 Duplicate panels are best prepared by using a standard panel measuring (165 × 430) mm and making a draw--
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down approximately 150 mm wide. After drying, the panel can then be cut in half lengthwise.
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stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
NOTE 2 For interior wall paints, a drying period of 28 days is suitable for classification according to EN 13300.
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
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8.2 Wet--scrub resistance
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Ensure that the pad--displacing system is parallel to the surface of the test panel and that the mounting device
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is not in contact with the scrub pad holder (see Figure 3).Figure 3). Place the test panel with the applied
Adjust space between Asian text and numbers, Tab
coating film in the base pan of the scrub testing machine on a float glass support and hold it down with clamps
stops: Not at 0.71 cm
(see Figure 4),Figure 4), but not so tight as to cause warping of the test panel.
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Adjust space between Asian text and numbers
Spread the washing liquid with a soft paint brush on the surface of the coating. Leave the liquid in contact with
the coating for (60 ± 5) s.
Formatted: FooterPageNumber
ISO/DISFDIS 11998:20252026(en) Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: Font: Bold
Formatted: HeaderCentered, Left

Key
Formatted: Key Title, Adjust space between Latin and
1 mounting device
Asian text, Adjust space between Asian text and
2 scrub pad holder numbers
3 abrasive pad
Formatted: Adjust space between Latin and Asian text,
4 pad--displacing thread Adjust space between Asian text and numbers, Tab
stops: Not at 0.7 cm + 1.4 cm + 2.8 cm + 3.5 cm +
A correct
4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
B incorrect
Figure 3 — Mounting of scrub pad holder
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Asian text, Adjust space between Asian text and
numbers
Formatted: Font: 10 pt
Formatted: Font: 10 pt
Formatted: FooterCentered, Left, Space Before: 0 pt,
Tab stops: Not at 17.2 cm
Formatted: Font: 11 pt
Formatted: FooterPageNumber, Left, Space After: 0 pt,
Tab stops: Not at 17.2 cm
Formatted: Font: Bold
Formatted: HeaderCentered
Formatted: Key Title, Adjust space between Latin and
Key
Asian text, Adjust space between Asian text and
1 test panel
numbers
2 coating
Formatted: Adjust space between Latin and Asian text,
3 float glass
Adjust space between Asian text and numbers, Tab
4 base pan
stops: Not at 0.7 cm + 1.4 cm + 2.8 cm + 3.5 cm +
5 clamp
4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Formatted: None, Adjust space between Latin and
Figure 4 — Test panel clamping arrangement
Asian text, Adjust space between Asian text and
numbers
Formatted: FooterPageNumber
ISO/DISFDIS 11998:20252026(en) Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Formatted: Font: 11 pt, Bold
Saturate the non-woven abrasive for (60 ± 5) s with washing liquid to a final mass of (4,0 ± 0,5) g. Place the
Formatted: Font: Bold
abrasive pad on the scrub pad holder and in contact with the coating film. The unprinted side of the pad shall
be the side in contact with the coating during the test.
Formatted: HeaderCentered, Left
Formatted: Adjust space between Latin and Asian text,
Start the scrub testing machine and operate it for the specified number of cycles; that is, 40 cycles or 200 cycles
Adjust space between Asian text and numbers
according to EN 13300 or according to the requirements of the client's specifications. The excess washing
liquid applied with the brush will be removed within the first cycle.
Detach the test panel from the machine and the float glass support, rinse it immediately with tap water, and
leave it to dry to constant mass in the same standard atmosphere already used in 8.1.8.1. Dry the test panels
to constant mass, i.e. until the results of two consecutive weightings of test panel do not differ by more than
Formatted: Adjust space between Latin and Asian text,
20 mg.
Adjust space between Asian text and numbers, Tab
stops: Not at 0.71 cm
To be able to calculate the scrubbed area, measure the length and width of the scrub trace on the coated panel
using a straight--edge ruler (6.7).(6.7). Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers, Tab
Record the residual dry mass of the test panel and coating film to the nearest 0,1 mg. stops: Not at 0.71 cm + 0.99 cm + 1.27 cm
Formatted: Adjust space between Latin and Asian text,
9 Expression of results
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9.1 Calculation of the loss in coating mass per unit area
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stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
9.1.1 Area traversed by the scrub pad
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Formatted: label
Calculate the area, A, in square metres, traversed by the scrub pad using Formula (1):Formula (1):
Formatted: where_keep-with-next, Adjust space
S×W
𝑆𝑆×𝑊𝑊
between Latin and Asian text, Adjust space between
A= 𝐴𝐴=
6 10
Asian text and numbers
(1)
Formatted: Adjust space between Latin and Asian text,
Adjust space between Asian text and numbers, Tab
where stops: Not at 0.7 cm + 1.4 cm + 2.8 cm + 3.5 cm +
4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
S is the scrub length, in millimetres;
Formatted: Adjust space between Latin and Asian text,
W is the scrub width, in millimetres.
Adjust space between Asian text and numbers, Tab
9.1.2 Loss in coating mass per unit area
stops: Not at 0.71 cm + 0.99 cm + 1.27 cm
Formatted: Adjust space between Latin and Asian text,
Calculate the loss in coating mass per unit area, L, in grams per square metre, using Formula (2):Formula (2):
Adjust space between Asian text and numbers
Formatted: Adjust space between Latin and Asian text,
m − m
𝑚𝑚 −𝑚𝑚
1 2 1 2
L= 𝐿𝐿 =
Adjust space between Asian text and numbers, Tab
𝐴𝐴
A
stops: Not at 0.7 cm + 1.4 cm + 2.1 cm + 2.8 cm +
(2)
3.5 cm + 4.2 cm + 4.9 cm + 5.6 cm + 6.3 cm + 7 cm
Formatted: label
where
Formatted
...
A is the area, in square metres, traversed;
Formatted
...
m1 is the initial mass, in grams, of the test panel and dry coating film;
Formatted
m2 is the mass, in grams, of the test panel and dry coating film after the defined number of scrub cycles. .
9.2 Calculation of mean loss in film thickness Formatted
...
Formatted: Font: 10 pt
Calculate the mean loss in dry--film thickness, L , in micrometres, using Formula (3):Formula (3):
dft
Formatted: Font: 10 pt
m − m
 L Formatted
1 2 .
L (3)
dft 
A×ρρ
df df Formatted: Font: 11 pt
Formatted
...
==
Formatted: Font: Bold
Formatted: HeaderCentered
𝑚𝑚 −𝑚𝑚 𝐿𝐿
1 2
𝐿𝐿 =( )=
dft
𝐴𝐴×𝜌𝜌 𝜌𝜌
df df
(3)
where
Formatted: where_keep-with-next
ρdf is the dry--film density, in grams per cubic centimetre, of the coating, determined in
Formatted Table
accordance with Annex A;Annex A;
Formatted: Default Paragraph Font
A, m , m and L are as specified in 9.1.19.1.1 and 9.1.2.9.1.2.
1 2
Formatted: Table body (+)
9.3 Assessment of wet--scrub resistance Formatted: Space Before: 12 pt, Adjust space betwe
...