SIST EN 927-14:2023

SLOVENSKI STANDARD
SIST EN 927-14:2023
01-maj-2023
Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 14.
del: Določanje nateznih lastnostii premaznih filmov
Paints and varnishes - Coating materials and coating systems for exterior wood - Part
14: Determination of tensile properties of coating films
Beschichtungsstoffe - Beschichtungsstoffe und Beschichtungssysteme für Holz im
Außenbereich - Teil 14: Bestimmung der Zugeigenschaften von Beschichtungsfilmen
Peintures et vernis - Produits de peinture et systèmes de peinture pour le bois en
extérieur - Partie 14 : Détermination des propriétés en traction des films de revêtement
Ta slovenski standard je istoveten z: EN 927-14:2023
ICS:
71.100.50 Kemikalije za zaščito lesa Wood-protecting chemicals
87.040 Barve in laki Paints and varnishes
SIST EN 927-14:2023 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 927-14:2023

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SIST EN 927-14:2023


EN 927-14
EUROPEAN STANDARD

NORME EUROPÉENNE

January 2023
EUROPÄISCHE NORM
ICS 87.040
English Version

Paints and varnishes - Coating materials and coating
systems for exterior wood - Part 14: Determination of
tensile properties of coating films
Peintures et vernis - Produits de peinture et systèmes Beschichtungsstoffe - Beschichtungsstoffe und
de peinture pour le bois en extérieur - Partie 14 : Beschichtungssysteme für Holz im Außenbereich - Teil
Détermination des propriétés en traction des films de 14: Bestimmung der Zugeigenschaften von
revêtement Beschichtungsfilmen
This European Standard was approved by CEN on 25 December 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

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. EN 927-14:2023 E
worldwide for CEN national Members.

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EN 927-14:2023
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 . 5
5.1 Film application device . 5
5.2 Test apparatus. 6
5.3 Coating thickness gauge. 6
6 Test specimens . 6
6.1 Sampling of coating products . 6
6.2 Preparation of test specimens . 6
6.3 Shape and size . 6
6.4 Thickness . 8
6.5 Conditioning . 8
6.6 Cutting of test specimens . 8
7 Test procedure . 9
7.1 General . 9
7.2 Measurement of test specimens . 9
7.3 Clamping of specimens . 9
7.4 Determination of tensile properties . 9
7.5 Determination of the tensile strength .11
7.6 Determination of the tensile strain at break .12
7.7 Determination of the tensile modulus of elasticity .13
8 Test report .14
Bibliography .15
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SIST EN 927-14:2023
EN 927-14:2023
European foreword
This document (EN 927-14:2023) has been prepared by Technical Committee CEN/TC 139 “Paints and
varnishes”, the secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by July 2023, and conflicting national standards shall be
withdrawn at the latest by July 2023.
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.
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 implement this European Standard: 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.
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Introduction
Wood as a natural exterior construction material may be protected from rain, sunlight and microbial
attack by a coating film, thus ensuring its appearance and mechanical integrity over many years.
However, since most coatings are permeable to some extent to moisture from rain and air humidity,
swelling of the wood and coating occurs. Consequent shrinking of the wood and coating occurs upon
drying. The magnitude of swelling and shrinking depends on the amount of moisture uptake and varies
depending on the wood species and on the direction of wood movement (longitudinal < radial <
tangential). These cyclic expansions and contractions lead to different stresses in the surface coating over
time. The coating should ideally stay intact over time and continue to protect the wood substrate. A
coating material that is too rigid and brittle will crack and fail allowing increased moisture and water
uptake, microbial attack, eventual complete coating failure and possible wood degradation. The tensile
properties of the coatings are thus very important for the service lifetime of the coating and wood
substrate.
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1 Scope
This document specifies a method for determining the tensile properties of free coating films, specifically
for exterior wood applications. Typical tensile properties of interest are the modulus of elasticity, the
tensile strength and the elongation at break during stretching of a free coating film at constant test speed.
The test methods specified in this document are applicable to coatings from which free films can be made.
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 927-1:2013, Paints and varnishes - Coating materials and coating systems for exterior wood - Part 1:
Classification and selection
EN ISO 527-1:2019, Plastics - Determination of tensile properties - Part 1: General principles
(ISO 527-1:2019)
EN ISO 2808, Paints and varnishes - Determination of film thickness (ISO 2808)
EN ISO 4618, Paints and varnishes - Terms and definitions (ISO 4618)
EN ISO 15528, Paints, varnishes and raw materials for paints and varnishes - Sampling (ISO 15528)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 4618 apply.
ISO and IEC maintain terminology 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
Tensile test specimens are prepared from free coating films and subjected to a tensile test under defined
conditions until they fail. During this procedure, the load sustained by the specimen and the elongation
behaviour are recorded.
This document is similar to EN ISO 527-3 and ISO 37 for the testing of plastic and rubber materials but
focusses on the specimen preparation and specific testing of free dry coating films made from liquid
paints and varnishes intended for application on exterior wooden substrates.
5 Apparatus and materials
5.1 Film application device
Coating films can be prepared by casting the liquid coating material in moulds or by applying it to a
suitable non-adhering substrate by a manual procedure or an automatic film applicator; see 6.2.
NOTE Automatic application devices are preferred as they move at constant speed and deliver a more uniform
final coating film.
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5.2 Test apparatus
The tensile test machine shall comply with the requirements of EN ISO 527-1:2019, 5.1, where applicable.
It should be equipped with selectable speed control (typical range: 10 mm/min to 200 mm/min), load
and strain indicator and temperature control unit. The strain indicator can either use crosshead travel
measurement or extensometer measurement. If an extensometer is used, an optical measurement device
is preferred as it does not touch and influence the specimen.
5.3 Coating thickness gauge
For film thickness measurement, all devices using mechanical scanning according to EN ISO 2808 or
equivalent methods are applicable.
6 Test specimens
6.1 Sampling of coating products
Take a representative specimen of the liquid coating material to be tested as specified in EN ISO 15528.
Deaerating of the coating material should be considered (e.g. in a centrifuge or in a high-speed vacuum
mixer).
6.2 Preparation of test specimens
Prepare the test specimens by casting the liquid coating material into shallow (e.g. silicone rubber-based)
moulds (in case of low viscosity coating materials) or by drawing the (more viscous) coating material as
a wet film on a flat support (e.g. on a PTFE coated metal plate, POM or inert foil, e.g. based on untreated
PP or PE) with a broad film applicator. The substrate shall be levelled horizontally before applying the
coating material.
The substrate shall allow the dry film to be removed easily without the need for additional wetting or
pre-stressing it. For cast films, apply the proper amount of (wet) coating material to produce the
requested dry film thickness.
In the case of inert foils as substrate it is recommended to attach them to the levelled flat support
(typically a glass plate) by wetting the backside with oil or water, avoiding entrapped air bubbles. The
wet coating film should preferably be applied on the foil with an automatic film applicator at an
appropriate speed.
The coating films to gain the final test specimens shall be prepared at controlled conditions in a standard
atmosphere [(23 ± 2) °C, (50 ± 10) % relative humidity or (20 ± 2) °C, (65 ± 10) % relative humidity]. The
cured coating films shall be free from cracks, bubbles or other defects.
Pre-treatment, e.g. by heat, or immersion in water to ease the removal of coating films from the substrate
shall not be used as it may strongly influence the mechanical film properties. Pre-treatments potentially
c
...