1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 15886:2010Conservation of culturalproperty Test methods Colour measurement ofsurfacesBS EN 15886:2010 BRITISH STANDARDNational forewordThis British Standard is the UK imple
2、mentation of EN 15886:2010.The UK participation in its preparation was entrusted to TechnicalCommittee B/560, Conservation of tangible cultural heritage.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all t
3、he necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 64876 2ICS 97.195Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy
4、Committee on 31 October 2010.Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15886 September 2010 ICS 97.195 English Version Conservation of cultural property - Test methods - Colour measurement of surfaces Conservation des biens culturels -
5、Mthodes dessai - Mesurage chromatique des surfaces Erhaltung des kulturellen Erbes - Prfmethoden - Farbmessung von matten Oberflchen This European Standard was approved by CEN on 7 August 2010. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions f
6、or 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 Management Centre or to any CEN member. This European Standard exists in three offic
7、ial 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 Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria,
8、 Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN
9、 COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15886:2010: EBS EN 15886:2010EN
10、15886:2010 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Terms and definitions .44 Principle 65 Test equipment 65.1 General 65.2 White object colour stimulus 66 Colour measurement of specimens .76.1 Test areas of specimens .76.2 Number of specimens .76.3 Preparation of specimens .
11、77 Colour measurement of indoor and outdoor objects 78 Test method 78.1 General 78.2 Measuring area and number of measurements 88.3 Reproducibility of measurements 89 Calculation and interpretation of results 89.1 CIELAB values .89.2 Calculation of total colour differences 89.3 Recommended options .
12、810 Test report 9Bibliography . 11BS EN 15886:2010EN 15886:2010 (E) 3 Foreword This document (EN 15886:2010) has been prepared by Technical Committee CEN/TC 346 “Conservation of cultural property”, the secretariat of which is held by UNI. This European Standard shall be given the status of a nationa
13、l standard, either by publication of an identical text or by endorsement, at the latest by March 2011, and conflicting national standards shall be withdrawn at the latest by March 2011. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent righ
14、ts. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. 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, C
15、yprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 15886:2010EN 15886:2010 (E)
16、4 1 Scope This European Standard describes a test method to measure the surface colour of porous inorganic materials, and their possible chromatic changes. No reference to the appearance of glossy surfaces is described. The method may be applied to porous inorganic materials either untreated or subj
17、ected to any treatment or ageing. The method is suitable for the measurement of colour coordinates of: representative surfaces of specimens, see 3.11; representative surfaces of objects, indoors or outdoors. 2 Normative references The following referenced documents are required for the application o
18、f this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced documents (including any amendments) apply. prEN 15898:2010, Conservation of cultural property Main general terms and definitions concerning conservation of cultural pr
19、operty 3 Terms and definitions For the purposes of this document, the terms and definitions given in prEN 15898:2010 and the following apply. 3.1 porous inorganic materials natural stones as well as artificial materials such as mortar, plaster, brick and others 3.2 chroma attribute of colour used to
20、 indicate the degree of departure of the colour from a grey of the same lightness NOTE See ASTM E 284. 3.3 lightness attribute by which a perceived colour is judged to be equivalent to one of a series of greys ranging from black to white NOTE See ASTM E 284. 3.4 hue attribute of a visual perception
21、according to which an area appears to be similar to one of the colours, red, yellow, green, and blue, or to a combination of adjacent pairs of these colours considered in a closed ring NOTE See the International Commission on Illumination CIE (1931) 3.5 reflectance factor R% percentage ratio of the
22、reflected radiant power compared to incident radiant power BS EN 15886:2010EN 15886:2010 (E) 5 3.6 CIE standard illuminant D65 reference illuminant having approximately the same relative spectral power distribution of a phase of daylight with a correlated colour temperature of approximately 6 500 K
23、3.7 CIE XYZ trichromatic system system for colour measurement established in 1931 by the International Commission on Illumination CIE (1931) NOTE The interpretation of numerical data is connected directly to visual perception. It is based on the principle that colours are obtained by mixing together
24、 the three imaginary colour as primaries defined X, Y, Z. These primaries define the reference frame in the tristimulus space and any set (X,Y,Z) is a vector in this space. The principal property of the reference frame is that the Y component is the luminance factor, generally given on a percentage
25、scale. 3.8 CIE 1931 standard colorimetric observer average observer whose colour matching properties correspond to the CIE colour matching functions for the 2 field size 3.9 CIE 1964 standard colorimetric observer average observer whose colour matching properties correspond to the CIE colour matchin
26、g functions for the 10 field size 3.10 CIE L*a*b* colour space 1976 mathematical transformation of the CIE XYZ space into a metric space NOTE 1 See Figure 1. NOTE 2 The L*a*b* system is useful for calculations of colour differences because it allows them to be defined by numerical values. NOTE 3 In
27、the CIE L*a*b* colour space the colour coordinates in this rectangular coordinate system are: L* - the lightness coordinate. The scale for L* ranges from 0 (black) to 100 (white); a* - the red/green coordinate, with +a* indicating redness and -a* indicating greenness; b* - the yellow/blue coordinate
28、 with +b* indicating yellowness and -b* indicating blueness. a*b*L*fFigure 1 L*a*b* colour space BS EN 15886:2010EN 15886:2010 (E) 6 3.11 specimen part considered representative of the material constituting an object. NOTE 1 The specimen can have different origins and can be taken from: materials si
29、milar to those constituting the object under study (e.g. stone quarries); reference materials, for instance, specifically prepared comparative materials. NOTE 2 The number and dimension of the specimens can be different depending on difficulties encountered in sampling the required amount of materia
30、l. 4 Principle The method is based on the determination of the colour of a surface with an instrumental quantification of colour, expressed numerically according to international methods defined by the International Commission on Illumination CIE. The colours are represented in a “colour space“, whe
31、re any colour in the visible range is defined by three coordinates. 5 Test equipment 5.1 General Common instruments used for colour measurement are tristimulus colorimeters or reflectance spectrophotometers characterized by: spectral range: 380 nm to 780 nm; acquisition data at least every 10 nm; CI
32、E standard illuminant: D65 (recommended), A, C; CIE standard colorimetric observer: 2 and 10 (recommended); reference system colour space: CIE x,y,Y and L*a*b*1). It is recommended that the instrument geometry conforms to the d/8 illumination and viewing condition specified by the CIE, where the ill
33、umination is diffused with the specular component excluded. Use of other geometries, such as 0/d, is also allowed. The test report shall specify the geometry used. 5.2 White object colour stimulus For the calculation of L*a*b* values, the white reference shall be constituted by a perfect reflecting
34、diffuser illuminated by the same light source as the tested specimen and/or object. 1) Usually the instruments available on the market are equipped with a software, which calculates the colorimetric parameters CIE x,y,Y and L*,a*,b* from the reflectance values. Otherwise these parameters can be calc
35、ulated using the CIE Tables. BS EN 15886:2010EN 15886:2010 (E) 7 6 Colour measurement of specimens 6.1 Test areas of specimens The tested surface areas shall be representative of the colour of the material under investigation. On inhomogeneous materials, the number of measurement points shall be ada
36、pted to the specimen as to obtain statistically representative values. Specimens shall be large enough to extend beyond the measurement area of the instrument. 6.2 Number of specimens A minimum of five representative specimens is considered suitable. However, if only a limited number of specimens ar
37、e available, the most representative specimen(s) shall be used. 6.3 Preparation of specimens The specimens shall be conditioned in equilibrium with the surrounding environment. Temperature (T) and Relative Humidity (RH) should be recorded. The surface of the specimens to be measured shall, if strict
38、ly necessary, be smoothed with sand paper with grain size of 82 m (corresponding to grit number P180 according to the FEPA2)classification) and wiped with a soft brush, bearing in mind that such action may alter the colour of the surface prior to measurement. Measurements taken before and after trea
39、tment shall be performed under the same environmental conditions. 7 Colour measurement of indoor and outdoor objects The area of measurement is the section of the surface of the object on which the colour measurements are carried out. The surface to be measured should, as far as practicable, be smoo
40、th and flat so as exclude external light from the area of measurement. Where no smooth, flat areas are available, this should be noted in the report. Sand paper shall not be used to smooth the surface of an object. Environmental parameters should, as far as is practicable, be reproduced when measure
41、ments are made. Relevant environmental conditions, including temperature and humidity should be recorded in the report. Colour measurements before and after treatment, and any subsequent measurement, should be carried out under the same environmental conditions. 8 Test method 8.1 General The surface
42、 to be measured shall be representative of the specimen and the object as a whole. The number of measurement points shall be adapted to the specimen or the object as to obtain statistically representative values. 2) FEPA Federation of European Producers of Abrasives. BS EN 15886:2010EN 15886:2010 (E
43、) 8 8.2 Measuring area and number of measurements The diameter of the measuring area and the equipment shall be appropriate to the type of material under investigation, and the size of the specimen or object. Heterogeneous surfaces may be measured using a measuring area with a diameter as large as p
44、ossible, in order to compensate variations in colour and texture, and to even out structural unevenness on the surface of the specimen or object, thus imitating the human visual process. Uniform specimens or objects with or without well-defined areas of different appearance (such as dark veins on li
45、ght marble) may be measured with a much smaller (1 mm) measuring field diameter to avoid (or define) any areas of in-homogeneity. The necessary number of measurements varies according to the homogeneity of the measuring area, but shall be at least five to obtain a reliable average value per specimen
46、 or per object. The measurements are taken at arbitrary locations of the surface In order to ensure precise repeated measurements, the selected measurement points shall be localised by either reference spatial coordinates or by annotated images. A grid delimiting the measurement area may be useful f
47、or this purpose, depending on the size of the specimen or the object. 8.3 Reproducibility of measurements Reproducibility of measurements is assessed by comparing two series of measurements made on the same surface under the same conditions and at different times, defined as moving the measuring hea
48、d/probe turning the instrument on and off, and recalibrating it. Repeat the measurements until the difference, expressed as E, between the average L* a* b* values of two successive series of measurements is E 1,5. 9 Calculation and interpretation of results 9.1 CIELAB values Calculate the CIELAB (CI
49、E L* a* b* 1976) values from the X, Y, Z values for each specimen. Daylight illuminant (D65) and 10 observer should be used. 9.2 Calculation of total colour differences The total colour difference E* between two measurements (L*1a*1b*1and L*2a*2b*2) is the geometrical distance between their positions in the CIELAB colour space. It is calculated using the following equation: )*(*2221,2baLE += where L* = L*2- L*1; corresponds to the lightness difference; a* = a*2- a*1; corresponds
