1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationPaints and varnishes Coating materials and coatingsystems for exterior wood Assessment of knot stainingresistance of wood coatingsPD CEN/TS 16359:2012National forewordThis Publis
2、hed Document is the UK implementation of CEN/TS 16359:2012.The UK participation in its preparation was entrusted to Technical CommitteeSTI/28, Paint systems for non-metallic substrates.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication d
3、oes not purport to include all the necessary provisions of acontract. Users are responsible for its correct application. The British Standards Institution 2012Published by BSI Standards Limited 2012ISBN 978 0 580 76733 3ICS 87.040Compliance with a British Standard cannot confer immunity fromlegal ob
4、ligations.This Published Document was published under the authority of theStandards Policy and Strategy Committee on 31 July 2012.Amendments issued since publicationAmd. No. Date Text affectedPUBLISHED DOCUMENTPD CEN/TS 16359:2012TECHNICAL SPECIFICATION SPCIFICATION TECHNIQUE TECHNISCHE SPEZIFIKATIO
5、N CEN/TS 16359 July 2012 ICS 87.040 English Version Paints and varnishes - Coating materials and coating systems for exterior wood - Assessment of knot staining resistance of wood coatings Peintures et vernis - Produits de peintures et systmes de peintures pour bois en extrieur - valuation de la rsi
6、stance des revtements pour bois aux taches provoques par les nuds Beschichtungsstoffe - Beschichtungsstoffe und Beschichtungssysteme fr Holz im Auenbereich - Beurteilung der Bestndigkeit von Holzbeschichtungen gegen Astausfrbung This Technical Specification (CEN/TS) was approved by CEN on 9 April 20
7、12 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 require
8、d 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 conver
9、sion 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxe
10、mbourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN
11、 All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TS 16359:2012: EPD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 2 Contents Page Foreword 31 Scope 52 Normative references 53 Terms and definitions .54 Test panels .54.1 Wood .54.2 Sampling of
12、 coating products 84.3 Preparation of coated panels .85 Equipment 85.1 Apparatus for accelerated ageing 85.2 Apparatus for colour measurements .86 Procedure of exposure 87 Measurements 87.1 Measurement of colour difference .87.2 Calculation of E* 97.3 Statistical evaluation .97.4 Flow diagram for te
13、st 98 Test report . 10Annex A (informative) Explanatory notes 11A.1 General . 11A.2 Wood material . 11A.3 Impregnation . 11A.4 Precision 11Bibliography . 12PD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 3 Foreword This document (CEN/TS 16359:2012) has been prepared by Technical Committee CEN/TC 139 “Pain
14、ts 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 and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENEL
15、EC Internal Regulations, the national standards organizations of the following countries are bound to announce this Technical Specification: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary
16、, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. PD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 4 Introduction The treatment of exterior wood surfaces has both ae
17、sthetic and protective functions. A vital purpose of a coating system is to protect against discoloration caused by wood extractives. Discoloration can be characterised as tannin staining or as knot staining. This document provides a method for assessment of discoloration of coatings on wood caused
18、by wood extractives in knots, i.e. it relates to knot staining only. PD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 5 1 Scope This Technical Specification specifies a test method for assessing the discoloration of coating systems on wood due to wood extractives from knots. The discoloration is measured b
19、y colorimetry 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, in whole or in part, are normatively referenced in this document and are indispensable for its application. F
20、or 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 4892-2:2006, Plastics Methods of exposure to laboratory light sources Part 2: Xenon
21、-arc lamps (ISO 4892-2:2006) EN ISO 15528, Paints, varnishes and raw materials for paints and varnishes Sampling (ISO 15528) ISO 554, Standard atmospheres for conditioning and/or testing Specifications ISO 7724-2, Paints and varnishes Colorimetry Part 2: Colour measurement ISO 7724-3, Paints and var
22、nishes Colorimetry Part 3: Calculation of colour differences 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 tannin staining appearance of discoloration on coated surfaces caused by wood extractives in the substrate 3.2 knot staining appearan
23、ce of discoloration on coated surfaces caused by wood extractives in knots 3.3 wood extractives low-molecular wood components soluble in organic solvents or water 3.4 sound knot knot that, at the relevant surface, is intergrown with the surrounding wood along more than 75 % of its circumference and
24、is free of decay SOURCE: EN 844-9:1997, 9.1.14 and EN 844-9:1997, 9.1.18. 4 Test panels 4.1 Wood The raw material for the test panels shall be panels of pine (Pinus silvestris) free from visible cracks, blue stain, bacterial attack and rot damage. The panels shall be dried to target moisture content
25、 18 % in PD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 6 accordance with EN 14298. The drying temperature shall not exceed 70 C during any part of the drying schedule. There are no specific demands on wood dimension, specific gravity, growth ring orientation, content of heartwood and surface structure,
26、however sawn panels 25 mm 100 mm with a considerable amount of knots is a suitable raw material. After drying, the panels shall be stored in an atmosphere in accordance with ISO 554 at (20 2) C/(65 5) % RH until equilibrium has been reached, i.e. normally minimum for one month and maximally for 6 mo
27、nths. From this dried and climatised wood material test panels with a nominal size of 150 mm 74 mm min. 10 mm are prepared with at least one sound knot with a diameter at least as large as the measuring aperture of the apparatus for colour measurement. The test panels shall be cut such that no part
28、of the test face contains material originating closer than 10 mm from the surface of the raw material. The test face shall be “fresh”; therefore the original wood material shall be sawn, cut or machined at least 10 mm below its original surface. A practical procedure of panel preparation is shown in
29、 Figure 1. The shown procedure is a suggestion, not a specification. PD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 7 Dimensions in millimetres Key 1 raw material is a pine panel with a sound knot at least as large as the measuring aperture of the colorimeter. The knot shall look sound and sufficiently l
30、arge on both sides of the panel 2 the original panel is divided in two equally sized panels, preferably by band sawing. No more panels of this type should be produced than can be further machined within one week after sawing 3 the two panels should be at least 10 mm thick at this stage 4 the test fa
31、ce to be further machined and coated is the freshly sawn surface designated 5 and 6 in Figure 1 Figure 1 Example of practical procedure for panel production NOTE 1 Following this procedure two panels each 150 mm 74 mm approximately 10 mm are produced from one initially 25 mm thick panel. It has been
32、 experienced that such two halves originating from the same initial panel, often but PD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 8 not always, perform similarly in the test. This provides an opportunity to use matched samples in test trials, e.g. coating one half of each matched pair of panels with a
33、reference coating. This is an option; it is not specified as the normal test procedure. For each coating system under test select a minimum of 20 test panels 150 mm 74 mm approximately 10 mm on a random basis from the available supply. NOTE 2 The number of panels has influence of the accuracy of the
34、 test. Plane the test face with an ordinary rotary planing machine and store the test panels (14 2) days at (20 2) C/(65 5) % RH with the planed surface exposed to the atmosphere of the climate chamber, (the surface shall not be obstructed). NOTE 3 The time interval between planing and coating has a
35、 decisive influence on knot staining. Freshly machined surfaces give a more pronounced discoloration than aged surfaces. It is therefore important to respect the specified two week ageing interval. 4.2 Sampling of coating products A representative sample of the product to be tested (or of each produ
36、ct in the case of a multicoat system) shall be taken as specified in EN ISO 15528. 4.3 Preparation of coated panels Apply the coating system respecting the method and spreading rate specified by the manufacturer with the product or products under test. Normally a white top coat should be applied. Un
37、less otherwise specified, dry the coated test panels at (20 2) C/(65 5) % RH for a period of (7 2) days. 5 Equipment 5.1 Apparatus for accelerated ageing Accelerated ageing of the coated test panels shall be performed in an apparatus in accordance with EN ISO 4892-2:2006. 5.2 Apparatus for colour me
38、asurements The colour shall be measured in CIELAB colour coordinates with an apparatus with illuminant D65/10 standard observer as specified in ISO 7724-2. Specular gloss may be included or excluded, but the selected principle should be stated. 6 Procedure of exposure The coated test panels are moun
39、ted in the exposure cabinet with the coated surface towards the xenon-arc lamps and exposed continuously for 72 h according to EN ISO 4892-2:2006, Method A, Cycle No. 1. Exposure period: 102 min dry, 18 min water spray. Black-panel temperature: (65 3) C. After 72 h of exposure, remove the coated tes
40、t panels from the exposure apparatus, blot any water from the surface and store the panels without obstructing the coated surface at 20 C/65 % RH for maximum 3 days before colour measurement. 7 Measurements 7.1 Measurement of colour difference The colour difference between the coated surface over th
41、e knot and the coated surface beside the knot is measured after the exposure with an instrument as specified in 5.2. PD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 9 7.2 Calculation of E* The colour difference E* is calculated for every single test panel according to ISO 7724-3 and designated E*1to E*n.
42、The mean E* for a test system is reported as the arithmetic mean value of all n individual measurements. E* = ( E*1-n)/n (1) where E* is the mean for a test system; n is the number of individual test samples. 7.3 Statistical evaluation The standard deviation of the above mean E* is calculated. 7.4 F
43、low diagram for test Figure 2 shows a flow diagram for testing. Acquire wood raw material Saw test panels to approximate size Select test panels and plane test surface Store at 20 C / 65 % RH min. 1, max. 6 month Store at 20 C / 65 % RH max. 7 days Store at 20 C / 65 % RH min. 12 days, max. 16 days
44、Coat test surface of the panels Expose acc. to EN ISO 4892-2:2006 Method A Cycle No. 1 Measure colour on knots and on adjacent surfaces Store at 20 C / 65 % RH min. 5, max. 9 days Store at 20 C / 65 % RH max. 3 days Complete report of the test Figure 1 Flow diagram for test An impregnation step may
45、be included immediately after planing (see A.3). PD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 10 8 Test report The test report shall contain at least the following information: a) reference to this Technical Specification; b) name and address of the testing laboratory; c) identification number of the t
46、est report; d) name and address of the organisation or the person ordered the test; e) type and manufacturer of apparatus for accelerated ageing according to 5.1 and type and manufacturer of apparatus for colour measurements specified in 5.2; f) date and person responsible for the sampling; g) date
47、of receipt of the coating system tested; h) type and identification of the coating or coating system under test; i) test results (number of replicates, arithmetic mean value of E* according to 7.2 and standard deviation according to 7.3); j) any deviation, by agreement or otherwise, from the test me
48、thod specified; k) the date of the test, and the person and laboratory responsible; l) authorisation date of the test report. PD CEN/TS 16359:2012CEN/TS 16359:2012 (E) 11 Annex A (informative) Explanatory notes A.1 General Wood material consists of both high-molecular components (cellulose, hemicell
49、ulose and lignin) and low-molecular components. The low-molecular components can have lipophilic as well as hydrophilic character. These low-molecular compounds are often referred to as wood extractives; they consist of various fats and fatty acids, steryl esters and sterols, terpenoids and waxes (long-chain alcohols and their acid esters and sugars). During outdoor exposure of wood containing wood extractives, these substance
