1、Designation: C 1649 08Standard Practice forInstrumental Transmittance Measurement of Color for FlatGlass, Coated and Uncoated1This standard is issued under the fixed designation C 1649; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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
3、 and uncoatedtransparent glass. See Terminology E 284.1.2 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
4、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:2D 2244 Practice fo
5、r Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesE 284 Terminology of AppearanceE 179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Properties ofMaterialsE 308 Practice for Computing the Colors of Objects
6、byUsing the CIE SystemE 1164 Practice for Obtaining Spectrometric Data forObject-Color EvaluationE 1348 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 measu
7、red in the totaltransmittance mode on a CIE-conforming diffuse instrument.(See Guide E 179 and Test Method E 1348.) 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
8、CIE 15:2004and Practice E 308.) For color measurement, use of a truncatedspectral range of 400 700 nm is acceptable. (SeeCIE 15:2004.) Further information on the UV absorbing char-acteristics of the glass or glass coating, or both, may bedetermined by examining the spectral data in the 350 - 400 nmr
9、ange. If the instrument allows spectral measurement above700 nm, useful information on the IR transmittance character-istics of the glass or glass coating may also be determined. Ifcoatings are present, they are assumed to reflect and partiallytransmit light.4. Significance and Use4.1 Color measurem
10、ent 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
11、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-ment
12、s in the total transmittance mode is required.5.2 In addition, a device for mounting the glass sample flushat the transmission port is required.5.3 The instrument and associated color quality software/firmware shall be capable of converting measured spectraltransmittance data to CIE L*, a* b*; Hunte
13、r L, a, b; or Y, x, yvalues calculated for CIE illuminant D65 and the CIE 1964 10degree standard observer. (See Practice E 1164.) Any of thosemappings will serve as a full numerical color descriptor. (SeePractice E 308.) CIE Y transmittance can also serve as an1This practice is under the jurisdictio
14、n of ASTM Committee C14 on Glass andGlass Products and is the direct responsibility of Subcommittee C14.11 on OpticalProperties.Current edition approved Jan. 1, 2008. Published January 2008.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servi
15、ceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from U.S. National Committee of the CIE (International Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 01
16、970, http:/www.cie-usnc.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.over-all indicator of transmission. For other illuminant/observer combinations, see Practice E 308 for guidance in use.For effective communication of color v
17、alues 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 of rectan-gular, polar, or elliptical color differences shall serve toquantify the difference between target product color and lotcolor
18、. See Practice D 2244.6. Materials6.1 Samples are uncoated or partially reflective coatedtransparent glass with defined substrate, coating compositions,and thicknesses.7. Hazards7.1 Consult Material Safety Data Sheets, and local regula-tions for all materials used in this test method.8. Color Instru
19、ment Calibration and Set up Procedure8.1 Prepare instrument for operation by following the in-strument manufacturers instructions.8.2 Use instrument standardization to set the color instru-ment to the assigned values for the transmission standardssupplied by the manufacturer or other suitable refere
20、ncematerial.8.3 To verify consistency over time in the performance ofthe color instrument, read and record color values of aninstrument diagnostic standard (such as a color standard ordidymium filter) at regular intervals. Care should be taken tovisually inspect these standards for any significant v
21、isualabrasion and replace it if warranted.8.4 As the stability characteristics of coated and un-coatedglass are generally good, the user may, at their option, read andrecord color values for a coated glass sample to documentconsistency in the measurement method over time. Care shouldbe taken to visu
22、ally inspect the coated glass sample for anysignificant visual abrasion and replace it if warranted.9. Measurement Method9.1 Place the glass sample at the transmittance measurementport.9.2 At a minimum, scan the sample over the range ofwavelengths required for measurement. Two scans with a 90rotatio
23、n of the samples are preferable. If practical and possible,scan at least one other area of the sample as well.9.3 Correction for reflection loss of uncoated glass (op-tional):9.3.1 Because of historical practices, some industries applya correction for reflection loss to the transmittance and othersd
24、o not. As a result, specifications based on transmitted colormeasurements of glass may differ from industry segment toindustry segment. Typically, the architectural glass industrydoes not use the correction, but the container glass industrydoes. The user of this document is advised to ascertain indu
25、strysegment practices before deciding to apply or not apply thereflection correction.9.3.2 When required by the respective glass industry, thecorrection is (See Appendix X1.):Tcorrected5 kTTmeasured(1)Where:kT=F2nairnglassnair21 nglass2!G10. Report10.1 Report the following information:10.1.1 Sample
26、identification,10.1.2 Color scale, illuminant, standard observer, instru-ment geometry and transmittance mode,10.1.3 Sample preparation and presentation conditions, in-cluding number and pattern of readings averaged, and10.1.4 Average color or color difference values, or both,relative to a product s
27、tandard color to nearest hundredth of aunit.NOTE 1Sample preparation includes items of glass description suchas the type and form (single layer versus multi-layer IG; laminated, patternand thickness), as well as the surface preparation technique (cleaningmethod prior to measurement, polishing).NOTE
28、2Sample presentation includes any side or positional informa-tion; the area of view measured in each reading; the number of readingsaveraged and if readings were taken in a specific pattern.10.1.5 The CIE Y value may also be reported to nearesthundredths of a unit, as an instrumental measurement of
29、theoverall transmittance of the transparent glass.11. Keywords11.1 coatings; glass; transmittanceC1649082APPENDIXX1. REFLECTION LOSS CALCULATIONSX1.1 Reflection loss, R at the sample surface is determinedby the refractive indices:R8 5Snair nglassnair1 nglassD2(X1.1)X1.2 Expressed as a correction fac
30、tor for transmission:k8T54nairnglassnair1 nglass!25 1 R8 (X1.2)X1.3 Because the glass sample has two reflecting surfaces,total reflection loss is:R52R811R8(X1.3)X1.4 As a result, the correction factor for transmissionbecomes:kT52nairnglassnair21 nair25 1 R (X1.4)X1.5 Approximate refractive indices (
31、relative to air) forsome commercial glasses:4Containers and windows (soda-lime silica) 1.52Laboratory ware (borosilicate) 1.47Other borosilicate 1.48Fiber glass (E-glass) 1.55High lead 1.54Fused silica 1.45ASTM International takes no position respecting the validity of any patent rights asserted in
32、connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the res
33、ponsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive caref
34、ul consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International
35、, 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).4Handbook of Glass Properties, Bansal and Doremus, Editors, Chapters 1 and 2,Academic Press, 1986.C1649083
