CEN/TS 927-9:2023

SLOVENSKI STANDARD
01-maj-2023
Nadomešča:
SIST-TS CEN/TS 927-9:2019
Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 9.
del: Ugotavljanje razslojne trdnostii
Paints and varnishes - Coating materials and coating systems for exterior wood - Part 9:
Determination of pull-off strength
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
Ta slovenski standard je istoveten z: CEN/TS 927-9:2023
ICS:
71.100.50 Kemikalije za zaščito lesa Wood-protecting chemicals
87.040 Barve in laki Paints and varnishes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TS 927-9
TECHNICAL SPECIFICATION
SPÉCIFICATION TECHNIQUE
January 2023
TECHNISCHE SPEZIFIKATION
ICS 87.040 Supersedes 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
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 9: Bestimmung der Abreißfestigkeit
This Technical Specification (CEN/TS) was approved by CEN on 18 December 2022 for provisional application.

The period of validity of this CEN/TS is limited initially to three years. After two years the members of CEN will be requested to
submit their comments, particularly on the question whether the CEN/TS can be converted into a European Standard.

CEN members are required to announce the existence of this CEN/TS in the same way as for an EN and to make the CEN/TS
available promptly at national level in an appropriate form. It is permissible to keep conflicting national standards in force (in
parallel to the CEN/TS) until the final decision about the possible conversion of the CEN/TS into an EN is reached.

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, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2023 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TS 927-9:2023 E
worldwide for CEN national Members.

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

European foreword
This document (CEN/TS 927-9:2023) has been prepared by Technical Committee CEN/TC 139 “Paints
and varnishes”, the secretariat of which is held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes CEN/TS 927-9:2018.
CEN/TS 927-9:2018:
— the title has been modified.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN/CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to announce this Technical Specification: 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, Türkiye and the
United Kingdom.
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.
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 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/
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.
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 pe
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