SIST EN ISO 11998:2026

• Abstract:

  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.

• Status: Not Published
• Public Enquiry End Date: 30-Nov-2025
• ICS: 87.040 - Paints and varnishes
• Technical Committee: IBLP - Paints and varnishes
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 05-Nov-2026
• Due Date: 10-Jan-2027
• Ref Project: EN ISO 11998:2026 - Paints and varnishes - Determination of wet-scrub resistance of coatings (ISO 11998:2026)

• Refers: SIST ISO 3696:1995 - Water for analytical laboratory use -- Specification and test methods
• Effective Date: 04-Nov-2026
• Referred By: SIST EN 16301:2021 - Natural stone test methods - Determination of sensitivity to accidental staining
• Effective Date: 28-Oct-2026
• Referred By: SIST EN 16301:2013 - Natural stone test methods - Determination of sensitivity to accidental staining
• Effective Date: 28-Oct-2026
• Referred By: SIST EN 13300:2023 - Paints and varnishes - Paints and varnishes for interior walls and ceilings - Classification
• Effective Date: 28-Oct-2026
• Referred By: SIST EN 16566:2014 - Paints and varnishes - Fillers for internal and/or external works - Adaptation of fillers to European standards
• Effective Date: 28-Oct-2026
• Revises: SIST EN ISO 11998:2006 - Paints and varnishes - Determination of wet-scrub resistance and cleanability of coatings (ISO 11998:2006)
• Effective Date: 01-Dec-2026

SIST EN ISO 11998:2026 is a standard for paints and varnishes that specifies an accelerated method for determining the wet-scrub resistance of coatings. It is used to compare coatings under a defined substrate, application method, drying condition and wet-scrubbing procedure. The document does not cover cleanability.

What does SIST EN ISO 11998:2026 specify?

SIST EN ISO 11998:2026 specifies how to measure the wet-scrub resistance of a dry coating film by repeated scrubbing under controlled conditions. The result is based on the loss in coating mass and the corresponding mean loss in film thickness, so the method is aimed at comparable test results rather than direct prediction of real-life cleaning performance.

The standard excludes cleanability from its scope. Its note explains why - wet-scrub resistance depends not only on the coating itself, but also on the substrate, application method and drying conditions, so the test uses a defined substrate, fixed application method, specified drying conditions and a defined wet-scrubbing method.

Annex	What it covers
Annex A	Determination of dry-film density of the coating
Annex B	Quality control of the non-woven abrasive
Annex C	Acceptance of new non-woven abrasive
Annex D	Preparation and formulation of reference paint
Annex E	Example of reference paint
Annex F	Details on interlaboratory comparison

What are the key requirements of SIST EN ISO 11998:2026?

SIST EN ISO 11998:2026 turns wet-scrub resistance into a controlled laboratory measurement with defined materials, apparatus and calculations. The key point for users is that the test only stays comparable if the coating, the substrate, the abrasive and the drying conditions are handled exactly as described.

Test principle and reporting basis

Clause 4 states that the coating is applied to a test panel, dried and conditioned, weighed, scrubbed in a scrub testing machine, washed, dried again and reweighed. The measured mass loss is then converted into mean loss in film thickness.

In practice, this means the test does not stop at a visual judgment. The final result is a calculated value, and the coating can be rated only by comparing that value with a specified limit agreed between the interested parties.

Materials and equipment

Clause 5 specifies a washing liquid based on sodium n-dodecylbenzenesulfonate in water meeting grade 3 of ISO 3696. Clause 6 defines the apparatus, including the test panel, film applicator, wet-scrub tester, scrub pad holder, technical non-woven abrasive, analytical balance and ruler.

This matters because the test is sensitive to small changes in equipment and consumables. The standard therefore fixes the panel material, the scrubber motion, the pad mass, the abrasive size and the weighing resolution so that different laboratories can reach comparable results.

Sampling and film preparation

Clause 7 requires a representative sample in accordance with ISO 15528 and sample examination and preparation in accordance with ISO 1513. Clause 8 then requires the coating to be drawn down with a film applicator, dried in a controlled atmosphere and prepared so that the dry film remains intact during the scrub test.

For users, this means the sample must be treated as a test specimen, not as a production batch at large. The drying duration is set by the customer on the basis of classification standards, legislation or technical justification, and it has to be recorded.

Wet-scrub procedure

Clause 8.2 describes the scrubbing step. The panel is mounted in the machine, the washing liquid is applied, the abrasive is saturated to the specified mass, and the machine is run for the specified number of scrub cycles.

This section also requires the test panel to be rinsed, dried to constant mass and then reweighed. Constant mass is defined operationally in the standard, so the laboratory must keep weighing until two consecutive values are close enough.

Results and calculations

Clause 9 gives the calculation route for the test result. It first determines the scrubbed area, then the loss in coating mass per unit area, and then the mean loss in dry-film thickness using the dry-film density from Annex A.

This is important in practice because the final value is not simply the weight loss of the panel. The coating density is part of the calculation, so the result reflects thickness loss rather than only mass loss.

Precision, quality control and test report

Clause 10 gives precision data from an interlaboratory study and shows how repeatability and reproducibility are handled for the method. Clause 11 lists the minimum contents of the test report, including product identification, the document reference, drying conditions, dry-coating density, abrasive identification, results, laboratory details, deviations, anomalies and test date.

For quality control, Annex B and Annex C are especially important. Annex B checks each batch of abrasive, and Annex C sets out how a new abrasive is accepted through an interlaboratory comparison.

What terms does SIST EN ISO 11998:2026 define?

SIST EN ISO 11998:2026 defines the following key terms for the scrub test.

• Scrub cycle - one reciprocal movement of the scrub pad over the scrub length in both directions.
• Scrub length - the stroke length plus the length of the pad.
• Stroke length - the distance traversed by one stroke of the apparatus.
• Wet-scrub resistance - the ability of a dry coating film to sustain less than a specified loss in film thickness, averaged over a defined area, after a defined number of wet-scrub cycles.
• Dry-film density - used in the calculation of mean loss in film thickness in Annex A, where it links mass loss to thickness loss.

Who uses SIST EN ISO 11998:2026?

SIST EN ISO 11998:2026 is used by paint and varnish laboratories, coating manufacturers, and quality control teams that need a repeatable way to compare wet-scrub performance. It is also relevant to testing laboratories that run performance tests for customers or for product classification.

Buyers, specifiers and technical staff use it when they need a defined test method for comparing coatings, especially where scrub resistance is part of product selection or classification. The document also supports work on abrasive qualification and reference paint preparation for laboratories that maintain the method.

What changed in SIST EN ISO 11998:2026 from the previous edition?

SIST EN ISO 11998:2026 cancels and replaces ISO 11998:2006. The document states that the third edition was technically revised, with these main changes:

• the title has been changed;
• cleanability has been deleted completely;
• the abrasive pad has been changed;
• the statistical data on reproducibility and repeatability have been updated.

Which standards are used with SIST EN ISO 11998:2026?

SIST EN ISO 11998:2026 uses these normative references and companion standards:

Standard	What it contributes
ISO 1513	Examination and preparation of test samples
ISO 1524	Fineness of grind, used in the reference paint preparation in Annex D
ISO 3270	Temperatures and humidities for conditioning and testing
ISO 3696	Water quality for the washing liquid
ISO 4618	Vocabulary for paints and varnishes
ISO 5725-2	Accuracy, repeatability and reproducibility for the interlaboratory comparison in Annex C
ISO 15528	Sampling of paints, varnishes and raw materials

What does the SIST EN ISO 11998:2026 document contain?

SIST EN ISO 11998:2026 contains the full test method, the result calculations and the supporting annexes needed to run and control the method. It includes figures for the scrub pad holder and the test panel clamping arrangement, plus a figure for the dry-film density specimen layout in Annex A.

The annexes provide the parts that make the method reproducible in practice. Annex A gives the dry-film density method and formula, Annex B and Annex C control the abrasive, and Annex D gives the reference paint formulation and preparation details in Table D.1.

Annex E gives an example reference paint in Table E.1, and Annex F summarizes the interlaboratory comparison used for precision data. The document therefore supports laboratory testing, quality control, method setup and comparison of wet-scrub resistance results.

SLOVENSKI STANDARD
oSIST prEN ISO 11998:2025
01-november-2025
Barve in laki - Določanje odpornosti proti mokremu drgnjenju premazov (ISO/DIS
11998:2025)
Paints and varnishes - Determination of wet-scrub resistance of coatings (ISO/DIS
11998:2025)
Beschichtungsstoffe - Bestimmung der Nassabriebbeständigkeit von Beschichtungen
(ISO/DIS 11998:2025)
Peintures et vernis - Détermination de la résistance au frottement humide des
revêtements (ISO/DIS 11998:2025)
Ta slovenski standard je istoveten z: prEN ISO 11998
ICS:
87.040 Barve in laki Paints and varnishes
oSIST prEN ISO 11998:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN ISO 11998:2025
oSIST prEN ISO 11998:2025
DRAFT
International
Standard
ISO/DIS 11998
ISO/TC 35/SC 9
Paints and varnishes —
Secretariat: BSI
Determination of wet-scrub
Voting begins on:
resistance of coatings
2025-09-10
ICS: 87.040
Voting terminates on:
2025-12-03
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
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RECIPIENTS OF THIS DRAFT ARE INVITED
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NOTIFICATION OF ANY RELEVANT PATENT
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Reference number
ISO/DIS 11998:2025(en)
oSIST prEN ISO 11998:2025
DRAFT
ISO/DIS 11998:2025(en)
International
Standard
ISO/DIS 11998
ISO/TC 35/SC 9
Paints and varnishes —
Secretariat: BSI
Determination of wet-scrub
Voting begins on:
resistance of coatings
ICS: 87.040
Voting terminates on:
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland Reference number
ISO/DIS 11998:2025(en)
ii
oSIST prEN ISO 11998:2025
ISO/DIS 11998:2025(en)
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 . 7
9.1 Calculation of the loss in coating mass per unit area .7
9.1.1 Area traversed by the scrub pad .7
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 .8
10.3 Reproducibility . .8
11 Test report . 8
Annex A (normative) Determination of dry-film density of the coating . 9
Annex B (normative) Quality control of the non-woven abrasive .12
Annex C (normative) Acceptance of new non-woven abrasive .13
Annex D (normative) Preparation and formulation of reference paint . 14
Annex E (informative) Example of reference paint .16
Annex F (informative) Details on interlaboratory comparison .18
Bibliography . 19

iii
oSIST prEN ISO 11998:2025
ISO/DIS 11998:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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;
— cleanability has been deleted completely;
— the abrasive pad has been changed;
— the statistical data on reproducibility and repeatability 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.

iv
oSIST prEN ISO 11998:2025
DRAFT International Standard ISO/DIS 11998:2025(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 1524, Paints, varnishes and printing inks — Determination of fineness of grind
ISO 3270, Paints and varnishes and their raw materials — Temperatures and humidities for conditioning and testing
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 in both directions
3.2
scrub length
stroke length plus the length of the pad

oSIST prEN ISO 11998:2025
ISO/DIS 11998:2025(en)
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
®1)
5.1 Washingliquid. Use a 2,5 g/l solution of sodium n-dodecylbenzenesulfonate (CAS-Nr 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 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 nominal
thickness 0,25 mm, approximately 430 mm long and not less than 80 mm wide.
Other types of plastics film may be used where the coating contains solvent which might adversely affect the
PVC film. 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.

oSIST prEN ISO 11998:2025
ISO/DIS 11998:2025(en)
Figure 1 — Mounting device
Dimensions in millimetres
Key
1 pins
Figure 2 — Scrub pad holder
2)
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) For information about a suitable technical non-woven abrasive, please contact the DIN Normenausschuss
Beschichtungsstoffe und Beschichtungen (NAB), Burggrafenstraße 6, 10787 Berlin, Germany.

oSIST prEN ISO 11998:2025
ISO/DIS 11998:2025(en)
Batch control of suitable technical non-woven pads: The quality of the technical non-woven abrasive has a
direct impact on the test result. Therefore, the quality of each batch shall be proven according to Annex B of
this document.
New technical non-woven abrasives should be proven according to Annex C in a round robin test.
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 that the resulting dry film is of such a thickness that, after the defined number of wet-scrub
cycles, the substrate is not exposed.
For the determination of wet-scrub resistance, dry the film at a temperature of (23 ± 2) °C and a relative
humidity of (50 ± 5) % for the required period. The drying time is specified by the customer on basis of
classification standards, legislations 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-down approximately 150 mm wide. After drying, the panel can then be cut in half lengthwise.
NOTE 2 For interior wall paints a drying period for 28 days is suitable for classification according to EN 13300.
8.2 Wet-scrub resistance
Ensure that the pad-displacing system is parallel to the surface of the test panel and that the mounting
device is not in contact with the scrub pad holder (see Figure 3). Place the test panel with the applied coating
film in the base pan of the
...