ASTM_C_1649_-_14.pdf

Designation:C164914Standard Practice forInstrumental Transmittance Measurement of Color for FlatGlass,Coated and Uncoated1This standard is issued under the fixed designation C1649;the number immediately following the designation indicates the year oforiginal adoption 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 practice provides guidelines for the instrumentaltransmittance measurement of the color of coated and uncoatedtransparent glass.See Terminology E284.1.2 The practice specifically excludes fluorescent and iri-descent samples.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 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 practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesE284 Terminology of AppearanceE179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Propertiesof MaterialsE308 Practice for Computing the Colors of Objects by Usingthe CIE SystemE1164 Practice for Obtaining Spectrometric Data for Object-Color EvaluationE1348 Test Method for Transmittance and Color by Spec-trophotometry Using Hemispherical Geometry2.2 CIE Standard:3CIE 15:2004 Colorimetry3.Summary of Practice3.1 The color of transparent glass is measured in the totaltransmittance mode on a CIE-conforming diffuse instrument.(See Guide E179 and Test Method E1348.)The glass color isexpressed in CIE tristimulus values based on spectral transmit-tance measurements over the full CIE spectral range of 350 780 nm with a maximum 10-nm band pass.(See CIE 15:2004and Practice E308.)For color measurement,use of a truncatedspectral range of 400 700 nm is acceptable.(See CIE15:2004.)Further information on the UV absorbing character-istics of the glass or glass coating,or both,may be determinedby examining the spectral data in the 350 400 nm range.Ifthe instrument allows spectral measurement above 700 nm,useful information on the IR transmittance characteristics ofthe glass or glass coating may also be determined.If coatingsare present,they are assumed to reflect and partially transmitlight.4.Significance and Use4.1 Color measurement quantifies the transmitted color forglass.The user defines an acceptable range of color appropriatefor the end use.A typical quality concern for transmittancecolor measurement of glass products is verification of lot-to-lotcolor consistency for end-user acceptance.4.2 If the transmitted color of a glass product is consistentfrom lot-to-lot and within agreed supplier-buyer acceptancecriteria,the products color is expected to be consistent andacceptable for end-use.5.Apparatus5.1 For color measurements,a CIE-conforming diffusesphere instrument capable of making transmission measure-ments in the total transmittance mode is required.5.2 In addition,a device for mounting the glass sample flushat the transmission port is required.1This practice is under the jurisdiction of ASTM Committee C14 on Glass andGlass Products and is the direct responsibility of Subcommittee C14.11 on OpticalProperties.Current edition approved May 1,2014.Published May 2014.Originallyapproved in 2008.Last previous edition approved in 2008 as C1649 08.DOI:10.1520/C1649-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from CIE,Commission Internationale de LEclairage,Wien,Austria,www.cie.co.at.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.3 The instrument and associated color quality software/firmware shall be capable of converting measured spectraltransmittance data to CIE L*,a*b*;Hunter L,a,b;or Y,x,yvalues calculated for CIE illuminant D65 and the CIE 1964 10degree standard observer.(See Practice E1164.)Any of thosemappings will serve as a full numerical color descriptor.(SeePractice E308.)CIE Y transmittance can also serve as anover-all indicator of transmission.For other illuminant/observer combinations,see Practice E308 for guidance in use.For effective communication of color values between sites,color measurements must be expressed in the same color scale,illuminant,and standard observer.5.4 The expression of a color difference in terms ofrectangular,polar,or elliptical color differences shall serve toquantify the difference between target product color and lotcolor.See