1、Designation: C609 07 (Reapproved 2014)Standard Test Method forMeasurement of Light Reflectance Value and Small ColorDifferences Between Pieces of Ceramic Tile1This standard is issued under the fixed designation C609; the number immediately following the designation indicates the year oforiginal adop
2、tion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of LightReflectance Value (LRV)
3、and visually small color differencebetween pieces of glazed or unglazed ceramic tile, using anyspectrophotometer that meets the requirements specified in thetest method. LRV and the magnitude and direction of the colordifference are expressed numerically, with sufficient accuracyfor use in product s
4、pecification.1.2 LRV may be measured for either solid-colored tile ortile having a multicolored, speckled, or textured surface. Fortile that are not solid-colored, an average reading should beobtained from multiple measurements taken in a patternrepresentative of the overall sample as described in 9
5、.2 of thistest method. Small color difference between tiles should onlybe measured for solid-color tiles. Small color differencebetween tile that have a multicolored, speckled, or texturedsurface, are not valid.1.3 For solid colored tile, a comparison of the test specimenand reference specimen shoul
6、d be made under incandescent,fluorescent and daylight illuminant conditions. The use ofmultiple illuminants allows the color difference measurementto be made without the risk of wrongly accepting a match whenthe tiles being compared are metamers. (See 3.1.4.)1.4 The values stated in inch-pound units
7、 are to be regardedas the standard. The values given in parentheses are forinformation only.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health pract
8、ices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C242 Terminology of Ceramic Whitewares and RelatedProductsD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesE259
9、Practice for Preparation of Pressed Powder WhiteReflectance Factor Transfer Standards for Hemisphericaland Bi-Directional GeometriesE284 Terminology of Appearance3. Terminology3.1 Definitions:3.1.1 color difference, E*and EHthe vector sum of thethree component differences L*, a*, and b*for E*andLH,a
10、H,bHfor EH. The superscript * indicates colordifference based on the use of CIELAB color space equations,while the subscript H indicates color difference based on theuse of the Hunter equations. EHis expressed in units of judds,while E*is a unit-less value. Either form of the E can besolved for usin
11、g the equation shown in 10.3. For both theCIELAB and Hunter equations, the values L, a, and b areobtained by calculating the component differences as follows:L 5 Lt2 Lra 5 at2 arb 5 bt2 brwhere:t = test specimen, andr = reference specimen.The quantity E has a positive value and it describes themagni
12、tude but not the direction of color difference between thetest specimen and the reference specimen. The direction of1This test method is under the jurisdiction ofASTM Committee C21 on CeramicWhitewares and Related Products and is the direct responsibility of SubcommitteeC21.06 on Ceramic Tile.Curren
13、t edition approved Jan. 1, 2014. Published February 2014. Originallyapproved in 1967. Last previous edition approved in 2007 as C609 07. DOI:10.1520/C0609-07R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book o
14、f ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1color difference depends upon the algebraic signs of thecomponents L, a, and b. A posi
15、tive L value means thatthe test specimen is lighter than the reference against which itis being compared, and a negative L value means that the testspecimen is darker. However, the algebraic signs of chroma-ticity components, a and b, do not convey an easilyvisualized difference in color attributes
16、and can best bevisualized by plotting the corresponding points in the chroma-ticity plane.33.1.2 color spacethe colors of opaque specimens such asceramic tile are described in terms of three color scales L, a,and b. Scale L is a measure of lightness, a is a measure ofredness or greenness, and b is a
17、 measure of yellowness orblueness. The units for each of the three scales are so chosenthat they represent equally perceptible color differences. Theinterrelation of these color scales is more readily visualized ifthe scales are represented geometrically as the three mutuallyperpendicular axes of a
18、three-dimensional color space, with theL axis in the vertical direction, the positive a axis (redness) tothe right, and the positive b axis (yellowness) in a counter-clockwise direction from the positive a axis (see Fig. 1).3.1.3 light reflectance value, (LRV)the luminance factorY, of a sample expre
19、ssed as a percent. Thus, a Y value of 70would equate to an LRV of 70%. The LRV indicates the portionof light cast on a sample that is not absorbed.3.1.4 metamersSee Terminology E284.3.1.5 reference specimenany tile for which a match isdesired.3.1.6 repeatabilitythe standard deviation of results ob-t
20、ained by the same operator using the same instrument insuccessive measurements.3.1.7 reproducibilitythe standard deviation of results ob-tained by different operators using the same or different typesof instruments in different laboratories.3.1.8 standardthe plaque or other media of establishedtrist
21、imulus value, against which standardization of the instru-ment is made.3.1.9 test specimenany piece of tile whose LRV or colordifference from a reference specimen is to be evaluated.3.1.10 tileSee Terminology C242.3.1.11 spectrophotometricmeasurement of the spectral re-flectance or transmittance cur
22、ve of a material.44. Summary of Test Method4.1 This test method explains the technique for measuringthe LRV and color of tile specimens with a spectrophotometricinstrument that meets the specified requirements. Such instru-ments should give results comparable to differences observedby the human eye,
23、 and yield for each color a unique, three-number characterization, having known relationship to thetristimulus values X, Y, and Z.4.2 Spectrophotometic measurement systems commonlyprovide measurement data in a variety of color units and allowfor automatic conversion of data from one color system toa
24、nother. Select equations are included in this test method formanual determination of LRV from Y, L*or LH. Equations arealso provided for calculation of L*,a*and b*and LH,aHand bHfrom tristimulus values X, Y, Z. The algebraic differences in L,a, and b values, between any two specimens, are then used
25、tocalculate the color difference, E. If manual calculations arerequired, consult the instrument supplier for conversions notprovided within this test method.4.3 The complete description of the amount and direction ofa color difference between any two pieces of solid colored tilecan be given simply a
26、s the three respective differences betweenthe pairs of values for L, a, and b. For some purposes, E aloneprovides enough information, since its magnitude gives a fairlygood correlation with human opinions about the size of a colordifference.4.4 To protect against approval of a metameric color match,
27、multiple illuminates must be used when evaluating colordifference between solid colored tiles.Atest specimen needs toprove suitable with respect to a reference specimen underincandescent, fluorescent and daylight illuminant conditions inorder to be judged as acceptable.5. Significance and Use5.1 Thi
28、s test method describes the means of determining theLRV of a tile specimen. Certain building codes require the useof materials rated by LRV. Application of this test methodprovides the means for rating ceramic tile. LRVs reported forceramic tile should include reference to the observer andilluminant
29、 for which the rating is valid.3Illing, A. M., Balinkin, I., “Precision in Measurement of Small ColorDifferences,” American Ceramic Society Bulletin , Vol 44, No. 12, 1965, pp.956962.4Billmeyer, F.W. Jr., Saltzman, M., Principles of Color Technology, 2nd Edition,John Wiley color equations; color mea
30、surement;glaze color; light reflectance; tristimulusASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rig
31、hts, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for
32、 revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing
33、 you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C609 07 (2014)5
