FprEN ISO 11998
(Main)Paints and varnishes - Determination of wet-scrub resistance of coatings (ISO/FDIS 11998:2026)
- 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
- Publication Date
- 02-Dec-2026
- Technical Committee
- CEN/TC 139 - Paints and varnishes
- Drafting Committee
- CEN/TC 139 - Paints and varnishes
- Current Stage
- 6055 - CEN Ratification completed (DOR) - Publishing
- Start Date
- 03-Oct-2026
- Completion Date
- 03-Oct-2026
FprEN ISO 11998 is a CEN publication of the ISO method for determining the wet-scrub resistance of paint and varnish coatings. It specifies an accelerated test for comparing how a coating withstands repeated wet cleaning on a defined substrate, under defined application, drying and scrubbing conditions. The document is used by laboratories, coating manufacturers, quality teams and buyers who need a common way to rate and compare coatings.
What does FprEN ISO 11998 specify?
FprEN ISO 11998 specifies an accelerated method for determining wet-scrub resistance, and it explicitly leaves out cleanability. In practice, that means the result is a controlled laboratory measure of scrub resistance, not a direct simulation of every real cleaning situation.
The standard is organized into Clauses 1 to 11 and Annexes A to F. The annexes supply supporting methods for density, abrasive control, and reference paint preparation and checking.
| Annex | What it covers |
|---|---|
| A | Determination of dry-film density of the coating |
| B | Quality control of the non-woven abrasive |
| C | Acceptance of new non-woven abrasive |
| D | Preparation and formulation of reference paint |
| E | Example of reference paint |
| F | Details on interlaboratory comparison |
The scope also makes an important practical point: wet-scrub resistance depends on the coating, the substrate, the application method, the drying conditions and other factors. The test therefore uses a defined substrate, a fixed application method, specified drying conditions and a defined wet-scrubbing procedure so that different laboratories can compare results in the same way.
What are the key requirements of FprEN ISO 11998?
FprEN ISO 11998 is built around a controlled sequence: apply the coating, dry and condition it, weigh it, scrub it for a defined number of cycles, then weigh it again and calculate the loss. The main output is the coating’s loss in mass and the corresponding mean loss in dry-film thickness.
Test principle and calculation
Clause 4 defines the principle of the method. A coating film is applied to a test panel, conditioned, exposed to wet scrub cycles in a scrub testing machine, and then reweighed. The standard then converts the mass loss into a thickness loss using the dry-film density from Annex A.
This matters because users often need a result they can compare across products or production lots. The method turns a physical wear test into a measurable performance value that can be used for classification or specification work.
Reagents and test equipment
Clause 5 specifies the washing liquid as a defined detergent solution made up with water meeting the standard’s water quality requirement. Clause 6 defines the main apparatus: the test panel, film applicator, scrub tester, pad holder, abrasive pad, analytical balance and ruler.
The equipment details matter because scrub resistance is sensitive to small changes in geometry, force and abrasion. If the panel, pad holder or abrasive do not match the method, the result can shift even when the coating itself has not changed.
Clause 6 also requires a new abrasive pad for every test and points to Annex B and Annex C for checking and accepting abrasive batches. That is important in practice because the abrasive pad has a direct effect on the result.
Sampling, film application and wet scrubbing
Clause 7 requires a representative sample and preparation according to the referenced sampling and sample-preparation standards. Clause 8 then sets out film application, drying, weighing, wetting of the coating, saturation of the abrasive pad and operation of the scrub tester.
For the reader, the key point is that the test is not just about the coating material. The drying conditions, the substrate behaviour and the handling of the panel all influence the final rating, so these steps have to be controlled and recorded.
Expression of results
Clause 9 gives three linked result calculations: the scrubbed area, the loss in coating mass per unit area, and the mean loss in dry-film thickness. The dry-film density used in the thickness calculation comes from Annex A.
This matters because some users need the mass-loss result, while others need the thickness-loss result for comparison or classification. The standard gives both paths and ties them to the same test run.
Precision, quality control and reporting
Clause 10 gives precision data from an interlaboratory study, including repeatability and reproducibility information. Clause 11 lists the items that belong in the test report, including product identification, drying conditions, dry-film density, abrasive identification, the results, deviations, anomalies and the test date.
Annexes B, C and D are especially important for routine use. Annex B controls the quality of the abrasive batch, Annex C sets out how a new abrasive is accepted, and Annex D provides the reference paint used for checking the method and the abrasive.
What terms does FprEN ISO 11998 define?
FprEN ISO 11998 defines the terms that control how the test is run and how the result is described.
- 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 travelled 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 - the density value used in Annex A to convert mass loss into thickness loss for the coating.
These terms matter because they fix the measurement basis. If a lab, supplier and buyer use the same definitions, their wet-scrub results can be compared without ambiguity.
Who uses FprEN ISO 11998?
FprEN ISO 11998 is used by coating laboratories, product development teams, quality control staff and third-party test labs. It is also relevant for manufacturers, specifiers and buyers who need a standard way to compare coatings on a wet-scrub basis.
In practice, it is used for formulation work, batch control, product comparison and classification work. The note in the document also shows its relevance where classifications such as EN 13300 use wet-scrub resistance in product evaluation.
What changed in FprEN ISO 11998 from the previous edition?
FprEN ISO 11998 is the third edition and it cancels and replaces ISO 11998:2006. The document states 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.
For users, that means the current edition focuses only on wet-scrub resistance and reflects revised test and precision information.
Which standards are used with FprEN ISO 11998?
FprEN ISO 11998 refers to several standards that support sampling, conditioning, vocabulary and precision work:
- ISO 1513 - examination and preparation of test samples.
- ISO 1524 - fineness of grind, used in Annex D when preparing the reference paint.
- ISO 3270 - temperatures and humidities for conditioning and testing.
- ISO 3696 - water quality for preparing the washing liquid.
- ISO 4618 - vocabulary for paints and varnishes.
- ISO 5725-2 - the basic method for assessing repeatability and reproducibility.
- ISO 15528 - sampling of paints, varnishes and raw materials.
- EN 13300 - cited as a classification context for wet-scrub resistance.
These references matter because they anchor the test method to common laboratory practice. They tell the user how to sample, condition, define terms and assess precision before the wet-scrub result is reported.
What does the FprEN ISO 11998 document contain?
FprEN ISO 11998 contains the full test method, the calculation steps, precision data and reporting requirements. It also includes figures for the pad holder and panel arrangement, plus formulas for area, mass loss and thickness loss.
The annexes add the supporting work needed to use the method consistently: dry-film density measurement, abrasive quality control, abrasive acceptance, reference paint preparation, an example reference paint and an interlaboratory comparison summary. In practice, the document supports both routine testing and method control in laboratories, quality systems and comparative product evaluations.
Relations
- Effective Date
- 12-Feb-2026
- Effective Date
- 12-Jun-2024
Frequently Asked Questions
FprEN ISO 11998 is a draft published by the European Committee for Standardization (CEN). Its full title is "Paints and varnishes - Determination of wet-scrub resistance of coatings (ISO/FDIS 11998:2026)". This standard covers: 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.
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.
FprEN ISO 11998 is classified under the following ICS (International Classification for Standards) categories: 87.040 - Paints and varnishes. The ICS classification helps identify the subject area and facilitates finding related standards.
FprEN ISO 11998 has the following relationships with other standards: It is inter standard links to ISO 11998, EN ISO 11998:2006. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
FprEN ISO 11998 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
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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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
STANDARDS MAY ON OCCASION HAVE TO
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BE CONSIDERED IN THE LIGHT OF THEIR
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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
...