Paints and varnishes - Coating materials and coating systems for exterior wood - Part 7: Assessment of knot staining resistance of wood coatings

This standard specifies a test method for assessing the discoloration of coating systems on wood due to wood extractives from knots. The discoloration is measured by colorimetry and the result is stated as the colour difference between the coated surface on the knot and the coated surface beside the knot.

Beschichtungsstoffe - Beschichtungsstoffe und Beschichtungssysteme für Holz im Außenbereich - Teil 7: Beurteilung der Beständigkeit von Holzbeschichtungen gegen Astausfärbung

Dieses Dokument legt ein Prüfverfahren zum Beurteilen der Verfärbung von Beschichtungssystemen auf Holz aufgrund von Holzinhaltsstoffen aus Ästen fest. Die Verfärbung wird farbmetrisch gemessen und das Ergebnis als der Farbabstand zwischen der beschichteten Oberfläche auf dem Ast und der beschichteten Oberfläche neben dem Ast angegeben.

Peintures et vernis - Produits de peinture et systèmes de peinture pour le bois en extérieur - Partie 7 : Évaluation de la résistance des revêtements pour bois aux taches provoquées par les nœuds

Le présent document spécifie une méthode d’essai pour évaluer la décoloration des systèmes de peinture sur bois causée par des extractibles situés dans les noeuds du bois. La décoloration est mesurée par colorimétrie et le résultat est énoncé comme la différence de couleur entre la surface revêtue sur le noeud et la surface revêtue à côté du noeud.

Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 7. del: Ocenjevanje odpornosti premazov proti obarvanju zaradi grč v lesu

General Information

Status
Published
Public Enquiry End Date
04-Dec-2018
Publication Date
11-May-2020
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
05-Mar-2020
Due Date
10-May-2020
Completion Date
12-May-2020

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SLOVENSKI STANDARD
SIST EN 927-7:2020
01-junij-2020
Nadomešča:
SIST-TS CEN/TS 16359:2012

Barve in laki - Premazi in premazni sistemi za zaščito lesa za zunanjo uporabo - 7.

del: Ocenjevanje odpornosti premazov proti obarvanju zaradi grč v lesu

Paints and varnishes - Coating materials and coating systems for exterior wood - Part 7:

Assessment of knot staining resistance of wood coatings
Beschichtungsstoffe - Beschichtungsstoffe und Beschichtungssysteme für Holz im

Außenbereich - Teil 7: Beurteilung der Beständigkeit von Holzbeschichtungen gegen

Astausfärbung

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

extérieur - Partie 7 : Évaluation de la résistance des revêtements pour bois aux taches

provoquées par les nœuds
Ta slovenski standard je istoveten z: EN 927-7:2020
ICS:
71.100.50 Kemikalije za zaščito lesa Wood-protecting chemicals
87.040 Barve in laki Paints and varnishes
SIST EN 927-7:2020 en,fr,de

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

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SIST EN 927-7:2020
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SIST EN 927-7:2020
EN 927-7
EUROPEAN STANDARD
NORME EUROPÉENNE
April 2020
EUROPÄISCHE NORM
ICS 87.040 Supersedes CEN/TS 16359:2012
English Version
Paints and varnishes - Coating materials and coating
systems for exterior wood - Part 7: Assessment of knot
staining resistance of wood coatings

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

de peinture pour le bois en extérieur - Partie 7 : Beschichtungssysteme für Holz im Außenbereich - Teil

Évaluation de la résistance des revêtements pour bois 7: Beurteilung der Beständigkeit von

aux taches provoquées par les nœuds Holzbeschichtungen gegen Astausfärbung
This European Standard was approved by CEN on 1 December 2019.

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, Turkey 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

© 2020 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 927-7:2020 E

worldwide for CEN national Members.
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SIST EN 927-7:2020
EN 927-7:2020 (E)
Contents Page

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

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

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

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

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

4 Test panels ......................................................................................................................................................... 6

4.1 Wood .................................................................................................................................................................... 6

4.2 Sampling of coating products ..................................................................................................................... 8

4.3 Preparation of coated panels ...................................................................................................................... 8

5 Equipment ......................................................................................................................................................... 8

5.1 Apparatus for accelerated ageing ............................................................................................................. 8

5.2 Apparatus for colour measurements ....................................................................................................... 8

6 Procedure of exposure .................................................................................................................................. 8

7 Measurements .................................................................................................................................................. 9

7.1 Measurement of colour difference ............................................................................................................ 9

7.2 Calculation of ΔE* ............................................................................................................................................ 9

7.3 Statistical evaluation ..................................................................................................................................... 9

7.4 Flow diagram for test ..................................................................................................................................... 9

8 Test report ...................................................................................................................................................... 10

Annex A (informative) Explanatory notes .......................................................................................................... 11

A.1 General ............................................................................................................................................................. 11

A.2 Wood material ............................................................................................................................................... 11

A.3 Impregnation ................................................................................................................................................. 11

A.4 Precision .......................................................................................................................................................... 11

Bibliography ................................................................................................................................................................. 12

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SIST EN 927-7:2020
EN 927-7:2020 (E)
European foreword

This document (EN 927-7:2020) 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 October 2020, and conflicting national standards shall

be withdrawn at the latest by October 2020.

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 16359:2012.

According to the CEN-CENELEC Internal Regulations, the national standards organizations 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, Turkey and the

United Kingdom.
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SIST EN 927-7:2020
EN 927-7:2020 (E)
Introduction

The treatment of exterior wood surfaces has both aesthetic and protective functions. A vital purpose of

a coating system is to protect against discoloration caused by wood extractives. Discoloration can be

characterized as tannin staining or as knot staining.

This document provides a method for assessment of discoloration of coatings on wood caused by wood

extractives in knots, i.e. it relates to knot staining only.
The method can be used for testing exterior and interior coatings for wood.

Previous investigations have shown that xenon arc exposure shows better correlation to natural

weathering than the fluorescent UV test method.
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SIST EN 927-7:2020
EN 927-7:2020 (E)
1 Scope

This document specifies a test method for assessing the discoloration of coating systems on wood due

to wood extractives from knots. The discoloration is measured by colourimetry and the result is stated

as the colour difference between the coated surface on the knot and the coated surface beside the knot.

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 14298, Sawn timber — Assessment of drying quality

EN ISO/CIE 11664-4, Colorimetry — Part 4: CIE 1976 L*a*b* colour space (ISO/CIE 11664-4)

EN ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling (ISO 15528)

EN ISO 16474-2:2013, Paints and varnishes — Methods of exposure to laboratory light sources — Part 2:

Xenon-arc lamps (ISO 16474-2:2013)

EN ISO 18314-1, Analytical colorimetry — Part 1: Practical colour measurement (ISO 18314-1)

ISO 554, Standard atmospheres for conditioning and/or testing — Specifications
3 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/
...

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