Paints and varnishes - Coating materials and coating systems for exterior wood - Part 9: Determination of pull-off strength

This document specifies a method for assessing the resistance of a coating system on wet wood to separation from the substrate by measuring the force necessary to detach or rupture the coating system by a normal tensile strain applied through an attached stud (dolly). Additional information is gained by noting the type and locus of failure. The force required for detachment will depend on several factors including the adhesion of the coating to the substrate and between intermediate coating layers. The procedure is not regarded as a direct means of measuring adhesion but an indicator of adhesive performance (adherence) under wet conditions.
A procedure for wetting the wood substrate is described. The test method is only suitable for wood and wood-based substrates.
For dry adhesion the test method can be carried out without wetting, in which case it will differ very little from EN ISO 4624.

Beschichtungsstoffe - Beschichtungsstoffe und Beschichtungssysteme für Holz im Außenbereich - Teil 9: Bestimmung der Abreißfestigkeit

Peintures et vernis - Produits de peinture et systèmes de peinture pour le bois extérieur - Partie 9 : Détermination de la résistance à l’arrachement

Le présent document spécifie une méthode d'évaluation de la résistance d'un système de peinture sur bois humide à la séparation du subjectile en mesurant la force nécessaire pour détacher ou rompre le système de peinture par une contrainte de traction normale appliquée au moyen d'un goujon (plot). Des informations supplémentaires sont obtenues en notant le type et l'emplacement de la rupture. La force requise pour le décollement dépendra de plusieurs facteurs, notamment de l'adhérence du revêtement au subjectile et entre les couches intermédiaires du revêtement. Le mode opératoire n'est pas considéré comme un moyen direct de mesure de l'adhésion, mais comme un indicateur de la performance adhésive (adhérence) dans des conditions humides.
Une méthode de mouillage du subjectile en bois est décrite. La méthode d'essai convient uniquement aux subjectiles en bois et en matériaux dérivés du bois.
Pour l'adhérence en condition sèche, la méthode d'essai peut être utilisée sans mouillage, auquel cas elle diffèrera très peu de l'EN ISO 4624.

Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 9. del: Ugotavljanje razslojne trdnosti po izpostavitvi vodi

General Information

Status
Not Published
Publication Date
24-Jan-2023
Current Stage
6060 - Definitive text made available (DAV) - Publishing
Start Date
25-Jan-2023
Due Date
22-Aug-2023
Completion Date
25-Jan-2023

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SLOVENSKI STANDARD
kSIST-TS FprCEN/TS 927-9:2022
01-oktober-2022

Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 9.

del: Ugotavljanje razslojne trdnosti po izpostavitvi vodi

Paints and varnishes - Coating materials and coating systems for exterior wood - Part 9:

Determination of pull-off strength after water exposure
Beschichtungsstoffe ¿ Beschichtungsstoffe und Beschichtungssysteme für Holz im
Außenbereich ¿ Teil 9: Bestimmung der Abreißfestigkeit nach Wasserbeanspruchung

Peintures et vernis - Produits de peinture et systèmes de peinture pour le bois extérieur -

Partie 9 : Détermination de la résistance à l’arrachement après exposition à l’eau

Ta slovenski standard je istoveten z: FprCEN/TS 927-9
ICS:
71.100.50 Kemikalije za zaščito lesa Wood-protecting chemicals
87.040 Barve in laki Paints and varnishes
kSIST-TS FprCEN/TS 927-9:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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kSIST-TS FprCEN/TS 927-9:2022
---------------------- Page: 2 ----------------------
kSIST-TS FprCEN/TS 927-9:2022
FINAL DRAFT
TECHNICAL SPECIFICATION
FprCEN/TS 927-9
SPÉCIFICATION TECHNIQUE
TECHNISCHE SPEZIFIKATION
August 2022
ICS Will supersede CEN/TS 927-9:2018
English Version
Paints and varnishes - Coating materials and coating
systems for exterior wood - Part 9: Determination of pull-
off strength after water exposure

Peintures et vernis - Produits de peinture et systèmes Beschichtungsstoffe ¿ Beschichtungsstoffe und

de peinture pour le bois extérieur - Partie 9 : Beschichtungssysteme für Holz im Außenbereich ¿ Teil

Détermination de la résistance à l'arrachement après 9: Bestimmung der Abreißfestigkeit nach

exposition à l'eau Wasserbeanspruchung

This draft Technical Specification is submitted to CEN members for Vote. It has been drawn up by the Technical Committee

CEN/TC 139.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.

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 supporting documentation.

Warning : This document is not a Technical Specification. It is distributed for review and comments. It is subject to change

without notice and shall not be referred to as a Technical Specification.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. FprCEN/TS 927-9:2022 E

worldwide for CEN national Members.
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kSIST-TS FprCEN/TS 927-9:2022
FprCEN/TS 927-9:2022 (E)
Contents Page

European foreword ....................................................................................................................................................... 3

Introduction .................................................................................................................................................................... 4

1 Scope .................................................................................................................................................................... 5

2 Normative references .................................................................................................................................... 5

3 Terms and definitions ................................................................................................................................... 5

4 Principle ............................................................................................................................................................. 5

5 Apparatus and materials .............................................................................................................................. 6

5.1 Test apparatus.................................................................................................................................................. 6

5.2 Test dollies ........................................................................................................................................................ 6

5.3 Adhesives ........................................................................................................................................................... 6

6 Test panels ......................................................................................................................................................... 7

6.1 Wood substrate ................................................................................................................................................ 7

6.2 Conditioning ...................................................................................................................................................... 7

6.3 Coating of test panels ..................................................................................................................................... 7

6.3.1 Coated panels not exposed to weathering ............................................................................................. 7

6.3.2 Coated panels exposed to weathering ..................................................................................................... 7

7 Procedure........................................................................................................................................................... 8

7.1 Testing conditions .......................................................................................................................................... 8

7.2 Preparation of the samples ......................................................................................................................... 8

7.3 Order of the test samples ............................................................................................................................. 8

7.3.1 Non-standard panels ...................................................................................................................................... 8

7.3.2 Standard EN 927 exposure panels ............................................................................................................ 8

7.4 Testing procedure ........................................................................................................................................ 10

7.5 Evaluation of fracture ................................................................................................................................. 10

8 Calculation and expression of results ................................................................................................... 11

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

10 Test report ...................................................................................................................................................... 11

Annex A (informative) Interpretation of test results ................................................................................... 13

Bibliography ................................................................................................................................................................. 14

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kSIST-TS FprCEN/TS 927-9:2022
FprCEN/TS 927-9:2022 (E)
European foreword

This document (FprCEN/TS 927-9:2022) has been prepared by Technical Committee CEN/TC 139

“Paints and varnishes”, the secretariat of which is held by DIN.
This document is currently submitted to the Vote on TS.
This document will supersede CEN/TS 927-9:2018.
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kSIST-TS FprCEN/TS 927-9:2022
FprCEN/TS 927-9:2022 (E)
Introduction

This document is one of two methods for assessing the resistance of the coating system to removal by

external forces provided by either cross-cutting or direct pull-off, both methods carried out under wet

conditions. Two existing ISO Standards (EN ISO 2409 and EN ISO 4624) specify similar test methods for

dry substrates in general, but make no provision for wet conditions, where wood coatings are known to

be particularly vulnerable. Both of the new methods take full account of the special nature of wood as a

substrate in terms of the method of wetting and the selection of the substrate.

Most of the currently used exterior coating systems are characterized by their propensity to being

penetrated by moisture both into and out of the wood. It might therefore be difficult to achieve a good

adhesion of these coatings under high moisture conditions. In cases of an already damaged coating film

or an increased presence of moisture in the boundary zone to the wood surface, even a short-term

exposure to water can be sufficient to weaken the adhesion of a coating film either to the substrate or

within the coating system. The described method is suitable for the testing of coatings for exterior wood

or wood-based materials and applicable for testing the wet adhesion of a single coat or multi-coat system.

In this test procedure the force, which is necessary to detach or pull-off the coating perpendicular to the

substrate is measured.

Furthermore, the nature of fracture of the coating is assessed to validate or reject and assist in the

interpretation of the result.
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kSIST-TS FprCEN/TS 927-9:2022
FprCEN/TS 927-9:2022 (E)
1 Scope

This document specifies a method for assessing the resistance of a coating system on wet wood to

separation from the substrate by measuring the force necessary to detach or rupture the coating system

by a normal tensile strain applied through an attached stud (dolly). Additional information is gained by

noting the type and locus of failure. The force required for detachment will depend on several factors

including the adhesion of the coating to the substrate and between intermediate coating layers. The

procedure is not regarded as a direct means of measuring adhesion but an indicator of adhesive

performance (adherence) under wet conditions.

A procedure for wetting the wood substrate is described. The test method is only suitable for wood and

wood-based substrates.

For dry adhesion the test method can be carried out without wetting, in which case it will differ very little

from EN ISO 4624.
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.

EN 927-3, Paints and varnishes - Coating materials and coating systems for exterior wood - Part 3: Natural

weathering test

EN 927-6, Paints and varnishes - Coating materials and coating systems for exterior wood - Part 6: Exposure

of wood coatings to artificial weathering using fluorescent UV lamps and water

EN 23270, Paints and varnishes and their raw materials - Temperatures and humidities for conditioning

and testing (ISO 3270)

EN ISO 4624:2016, Paints and varnishes - Pull-off test for adhesion (ISO 4624:2016)

3 Terms and definitions
No terms and definitions are listed in this document.

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

• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
4 Principle

The product or system under test is applied at uniform thickness to flat wood-based panels of uniform

surface texture.

After drying/curing the coating system, dollies are glued directly to the surface of the coated panels.

After curing of the adhesive, a circular groove is milled or cut around the dollies. Water is deposited in

the groove for a time interval that ensures a complete wetting of the wood–coating interface beneath the

dollies.

After the complete wetting of the wood-coating interphase the bonded dolly/substrate assemblies are

placed in a suitable tensile tester. The bonded assemblies are subjected to a controlled tensile test (pull-

off test) and the force required to break is measured.
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kSIST-TS FprCEN/TS 927-9:2022
FprCEN/TS 927-9:2022 (E)

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

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

occur and should be recorded as shown in Table 1.
5 Apparatus and materials
5.1 Test apparatus

Mobile test apparatus or tension testing machines as described in EN ISO 4624. The tensile stress shall

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

substantially uniform rate, not greater than 1 MPa/s, such that failure of the test assembly occurs within

90 s. Suitable designs for applying the tensile stress are shown in EN ISO 4624:2016, 5.1 Figures 1 and 2,

or in 5.1, Figure 1 (below).

The apparatus shall permit recording of the applied force with an accuracy of ± 1 %.

It is permissible to use different types of pull
...

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