EN 927-5:2022
(Main)Paints and varnishes - Coating materials and coating systems for exterior wood - Part 5: Assessment of the liquid water permeability
Paints and varnishes - Coating materials and coating systems for exterior wood - Part 5: Assessment of the liquid water permeability
This part of EN 927 specifies a test method for assessing the liquid water permeability of coating systems for exterior wood.
Beschichtungsstoffe - Beschichtungsstoffe und Beschichtungssysteme für Holz im Außenbereich - Teil 5: Beurteilung der Wasserdurchlässigkeit
Dieser Teil von EN 927 legt ein Prüfverfahren zum Bewerten der Wasserdurchlässigkeit von Beschichtungs¬systemen für Holz im Außenbereich.
Peintures et vernis - Produits de peinture et systèmes de peinture pour le bois en extérieur - Partie 5 : Détermination de la perméabilité à l'eau liquide
La présente partie de l’EN 927 spécifie une méthode d’essai pour évaluer la perméabilité à l’eau liquide des systèmes de peinture pour le bois en extérieur.
Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 5. del: Ocenjevanje prepustnosti vode
General Information
RELATIONS
Standards Content (sample)
SLOVENSKI STANDARD
oSIST prEN 927-5:2021
01-januar-2021
Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 5.
del: Ocenjevanje prepustnosti vodePaints and varnishes - Coating materials and coating systems for exterior wood - Part 5:
Assessment of the liquid water permeabilityBeschichtungsstoffe - Beschichtungsstoffe und Beschichtungssysteme für Holz im
Außenbereich - Teil 5: Beurteilung der Wasserdurchlässigkeit
Peintures et vernis - Produits de peinture et systèmes de peinture pour le bois en
extérieur - Partie 5 : Détermination de la perméabilité à l'eau liquideTa slovenski standard je istoveten z: prEN 927-5
ICS:
71.100.50 Kemikalije za zaščito lesa Wood-protecting chemicals
87.040 Barve in laki Paints and varnishes
oSIST prEN 927-5:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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oSIST prEN 927-5:2021
DRAFT
EUROPEAN STANDARD
prEN 927-5
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2021
ICS 87.040 Will supersede EN 927-5:2006
English Version
Paints and varnishes - Coating materials and coating
systems for exterior wood - Part 5: Assessment of the
liquid water permeability
Peintures et vernis - Produits de peinture et systèmes Beschichtungsstoffe - Beschichtungsstoffe und
de peinture pour le bois en extérieur - Partie 5 : Beschichtungssysteme für Holz im Außenbereich - Teil
Détermination de la perméabilité à l'eau liquide 5: Beurteilung der Wasserdurchlässigkeit
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 139.If this draft becomes a European Standard, 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.
This draft European Standard was established by CEN 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, 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 European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 927-5:2021 E
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Contents Page
1 Scope .................................................................................................................................................................... 5
2 Normative references .................................................................................................................................... 5
3 Terms and definitions ................................................................................................................................... 5
4 Principle ............................................................................................................................................................. 5
5 Test panels ........................................................................................................................................................ 6
5.1 Wood .................................................................................................................................................................... 6
5.2 Preparation and selection of test panels ................................................................................................ 6
5.3 Preparation of coated and uncoated panels ......................................................................................... 7
5.3.1 Wood conditioning ......................................................................................................................................... 7
5.3.2 Panel selection ................................................................................................................................................. 7
5.3.3 Coating application ........................................................................................................................................ 9
5.3.4 Sealing and conditioning .............................................................................................................................. 9
5.3.5 Dry film thickness ........................................................................................................................................... 9
6 Apparatus ........................................................................................................................................................ 10
7 Procedure ........................................................................................................................................................ 10
7.1 Pre-conditioning ........................................................................................................................................... 10
7.2 Absorption cycle ............................................................................................................................................ 10
7.3 Optional testing of weathered panels .................................................................................................... 11
8 Calculation and expression of results ................................................................................................... 11
9 Precision .......................................................................................................................................................... 11
9.1 Repeatability (r) ............................................................................................................................................ 11
9.2 Reproducibility (R) ...................................................................................................................................... 11
10 Test report ....................................................................................................................................................... 11
Annex A (informative) Interpretation of test results and further calculation..................................... 12
Annex B (informative) Suggested form for specifying application parameters .................................. 14
B.1 General.............................................................................................................................................................. 14
B.2 Specifying complete coating system ...................................................................................................... 14
B.3 Equipment ....................................................................................................................................................... 14
B.4 Process .............................................................................................................................................................. 14
B.5 Spreading rate ................................................................................................................................................ 14
B.6 Flash-off ............................................................................................................................................................ 15
B.7 Drying and curing ......................................................................................................................................... 15
B.8 Overcoating intervals .................................................................................................................................. 15
B.9 Sanding ............................................................................................................................................................. 15
Bibliography ................................................................................................................................................................. 19
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European foreword
This document (prEN 927-5:2021) 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 CEN Enquiry.
This document will supersede EN 927-5:2006.
In comparison with the previous edition, the following technical modifications have been made:
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Introduction
The treatment of exterior wood surfaces has both aesthetic and protective functions. A vital purpose of
a coating system is to protect the wood against aesthetic deterioration (e.g. blue stain attack) and
dimensional changes. Because such attacks are mainly caused by high moisture contents in the wood, a
knowledge of the relative water permeability properties of coating materials applied to exterior wood is
helpful in selecting products for particular end-use applications, as described in EN 927-1.
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1 Scope
This part of EN 927 specifies a test method for assessing the liquid water permeability of coating
systems for exterior wood.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 undated references, the latest edition of the referenced
document (including any amendments) applies.EN ISO 2808:2019, Paints and varnishes — Determination of film thickness (ISO 2808:2020)
ISO 554, Standard atmospheres for conditioning and/or testing — Specifications3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http://www.electropedia.org/— ISO Online browsing platform: available at https://www.iso.org/obp
3.1
water absorption
ability of a coated or uncoated wood panel to absorb water from liquid or vapour
3.2
water permeability
ability of a coating system to allow the transmission of water as liquid or vapour
[SOURCE: EN 927-1:2013, definition 3.13]3.3
stable mass
mass achieved when the difference between two subsequent weighings within 24 h does not exceed
0,2 %4 Principle
Water permeability is assessed by measuring the water uptake over a 72 h period of a coated test panel
exposed to liquid water.The coating under test is applied to the face of a defined test panel where the remaining face and sides
are carefully sealed using a sealer of a defined mandatory low permeability.Results are expressed as water absorption of coated wood panels in grams per square metre test
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5 Test panels
5.1 Wood
The wood shall be spruce (Picea abies) that has been selected to be free from knots and cracks, to be
straight-grained and of normal growth rate (i.e. between 3 and 8 annual rings per 10 mm). The
inclination of the growth rings to the test face shall be (45 ± 10)°. See Figure 1.
The wood shall be free from blue stain and evidence of surface or bulk infection. Abnormal porosity
(caused by bacterial attack) shall be avoided.Abnormally porous wood can be detected qualitatively by the rapid absorption of a drop of propan-2-ol
(isopropanol) applied to the surface; the drop should not be absorbed in less than 30 s by normal wood.
The test should be carried out at not less than six places, widely separated on the rear face of the test
panel.3 3
The density of the wood shall be between 0,4 g/cm and 0,5 g/cm when measured at an equilibrium
moisture content of approximately 12 %. The measured density shall be recorded.Condition the wood prior to conversion into test panels in accordance with ISO 554 at (20 ± 2) °C and a
relative humidity of (65 ± 5) %.Dimensions in millimetres
Key
1 front of panel (test face)
a min. 3, max. 8 growth rings/10 mm
α angle of growth rings to test face min. 35°, max. 55°
Figure 1 — Selection of wood
5.2 Preparation and selection of test panels
Convert the conditioned wood into panels (340 ± 2) mm × (70 ± 2) mm × (20 ± 2) mm in size. It is
intended that after coating one panel 150 mm in length will be cut from each end of this 340 mm long
panel. This will leave an off-cut Cc approximately 40 mm in length from the middle of the panel, to be
used in due course for the determination of film thickness (see 5.3.5 and Figure 2).
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The panels shall be planed all round to a smooth and uniform finish. Any panels showing surface
splitting shall be rejected.5.3 Preparation of coated and uncoated panels
5.3.1 Wood conditioning
Prior to coating, condition the panels to constant mass in accordance with ISO 554 at (20 ± 2) °C and a
relative humidity of (65 ± 5) %. Panels shall be weighed at intervals of not less than one day until they
have reached a stable mass (see 3.3).5.3.2 Panel selection
Select three panels for each of the coatings to be tested. Select also three panels for testing the sealer
product; this set of panels will serve as sealed controls (see Figure 2).Mark each panel to identify the test face as that convex to the annual rings.
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Dimensions in millimetres
Key
A preparation of coated samples
B preparation of sealed samples
1 3 panels (340 × 70 × 20)
2 6 panels (150 × 70 × 20)
3 3 panels (340 × 70 × 20)
4 3 off-cuts appr. (35 × 70 × 20) for measurements of paint film thickness
a coating of front sides
b cutting
c sealing of edges and back sides
d cutting and sealing of all sides and edges, discard off-cuts
Figure 2 — Cutting of test panels
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5.3.3 Coating application
Coating systems shall be applied according to the manufacturer's specifications.
Apply each test coating system to the test face only (convex side of the panels). Each coating system
under test requires 3 test panels (340 mm × 70 mm × 20 mm).When the coating systems have dried, cut a test panel 150 mm in length from both ends of each long
panel (see Figure 2).The three small coated off-cuts C are used for the determination of film thickness.
Three additional panels are required to check the test face with the selected sealer. This sealer and the
number of layers should be identical with the later on used sealer for sealing the test panels (150 mm ×
70 mm × 20 mm). The liquid water permeability of the sealer shall not exceed 30 g/m in 72 h (see
Figure 2).Additional information is given in Annex B.
5.3.4 Sealing and conditioning
Panels shall be sealed in the same way whether they are applied for test coatings or control of sealer.
Seal the sides, end-grains and reverse faces of the panels against water entry using at least two coats of
a flexible moisture-impermeable coating, for example a solvent-free epoxy or polyurethane paint. The
sealer shall cover the edges completely and overlap the test face by 2 mm (see Figure 3). Apply the
sealer to the end grain so many times that a closed and uniform film is obtained.
Dimensions in millimetresKey
1 test face
2 2 mm
l length of the test face
w width of the test face
Figure 3 — Sealing of panels
After sealing, condition the panels in the controlled environment (see 5.3.1) until constant mass is
achieved (for typically 7 to 28 days). After drying of the sealer measure and record the actual test area
of each panel (see Figure 3).5.3.5 Dry film thickness
Determine the dry film thickness of the coating on the off-cuts (see Figure 2) of the test panels. Remove
one small chip of coated wood from each of the off-cuts and examine by microscopy in accordance with
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EN ISO 2808:2019, method 6A. Make 5 measurements on each chip and calculate and record the mean
value in micrometres.The dry film thickness is defined as the thickness of the layer on (above) the wood surface. Systems may
penetrate the wood material to some extent, but this part is not included in the determination.
6 Apparatus6.1 Microscope for measurement of dry film thickness in accordance with EN ISO 2808:2019, method
6A.6.2 Conditioning room, of appropriate size, controlled at a temperature of (20 ± 2) °C and a relative
humidity of (65 ± 5) %, in accordance with ISO 554.6.3 Container for deionized water, of size sufficient to hold the all the panels under test.
6.4 Balance, capable of weighing to the nearest 0,01 g.7 Procedure
7.1 Pre-conditioning
It is known that the water permeability of some types of coating can change markedly during a
relatively short period of exposure to water. For such coatings the values of water permeability
obtained during a short period of contact with water might not be representative of those obtained
during long-term service. For this reason all panels shall be subjected to a leaching procedure before
commencement of the absorption cycle.This procedure shall be carr
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