1、Designation: D 3134 97 (Reapproved 2003)Standard Practice forEstablishing Color and Gloss Tolerances1This standard is issued under the fixed designation D 3134; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.INTRODUCTIONPermissible color and gloss deviations from a standard are generally dependent upon the colordiscrimination of the observer, on
3、 the lighting and surround in which the material is viewed, and onspecial considerations related to the design, manufacture, and practical usage of the colored materialor object. The tolerances, therefore, may be influenced by economic, technical, psychological, andpractical requirements. In many ci
4、rcumstances, acceptability of color and gloss deviations from astandard may differ appreciably from the perceptibility of deviations such as on-tone fadingpreferences, large tolerances for luminance variation, nongreen bias, or nonyellow bias. With properallowances, perceptibility data can be used a
5、s an aid to develop permissible tolerances. Finally, thesum of all these considerations should result in a specification acceptable to both buyer and seller.1. Scope1.1 This practice describes a procedure for establishingtolerances and evaluating the color and gloss of specimens withrespect to speci
6、fied standards. This practice is appropriate fornonfluorescent opaque specimens.1.2 This practice does not indicate the extent of tolerances,but gives guidance on how they can be set. For productspecification, the tolerances between specimens and the speci-fied standard should be agreed upon between
7、 the purchaser andthe seller.1.3 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
8、 prior to use.2. Referenced Documents2.1 ASTM Standards:2D 523 Test Method for Specular GlossD 1535 Practice for Specifying Color by the Munsell Sys-temD 1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely Illuminated Opaque MaterialsD 2244 Practice for Calculation of Colo
9、r Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD 3964 Practice for Selection of Coating Specimens forAppearance MeasurementD 4449 Test Method for Visual Evaluation of Gloss Differ-ences Between Surfaces of Similar AppearanceD 5531 Guide for Preparation, Maintenance, a
10、nd Distribu-tion of Physical Product Standards for Color and Geomet-ric Appearance of CoatingsE 284 Terminology of AppearanceE 308 Practice for Computing the Colors of Objects byUsing the CIE SystemE 312 Practice for Description and Selection of Conditionsfor Photographing SpecimensE 805 Practice fo
11、r Identification of Instrumental Methods ofColor or Color-Difference Measurement of MaterialsE 1164 Practice for Obtaining Spectrophotometric Data forObject-Color EvaluationE 1331 Test Method for Reflectance Factor and Color bySpectrophotometry Using Hemispherical GeometryE 1345 Practice for Reducin
12、g the Effect of Variability ofColor Measurement by Use of Multiple MeasurementsE 1349 Test Method for Reflectance Factor and Color bySpectrophotometry Using Bidirectional GeometryE 1360 Practice for Specifying Color by Using the OpticalSociety of America Uniform Color Scales SystemE 1499 Guide to th
13、e Selection, Evaluation, and Training ofObserversE 1541 Practice for Specifying and Matching Color Usingthe Colorcurve SystemE 1708 Practice for Electronic Interchange of Color andAppearance Data1This practice is under the jurisdiction of ASTM Committee E12 on Color andAppearance and is the direct r
14、esponsibility of Subcommittee E12.11 on VisualMethods.Current edition approved Dec. 1, 2003. Published December 2003. Originallyapproved in 1972. Last previous edition approved in 1997 as D 3134 97.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service
15、at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.2.2 CIE Publication:No. 15.2 Colorimetry 2nd ed.
16、33. Terminology3.1 DefinitionsFor definitions of terms related to thispractice see Terminology E 284.4. Summary of Practice4.1 This practice consists of recommendations for the se-lection of a standard, the necessary physical measurements toassess the permanence of the standard to reproduce it whenn
17、eeded, and to establish tolerances.4.2 Recommendations are given for the determination of theconformance of a specimen to preestablished color and glosstolerances by instrumental or visual means.5. Significance and Use5.1 Color specifications are centered around exact positionsin color space. Corres
18、pondingly, gloss specifications are cen-tered around an exact position on the gloss scale. Because it isdifficult to achieve these exact positions repeatedly, it isnecessary to specify tolerances that are acceptable to both thebuyer and the seller. This practice details the procedure foraccomplishin
19、g this goal.6. Specimens6.1 The exact method of preparation of the specimen shallbe agreed upon between the purchaser and the seller. However,for the highest precision in instrumental measurements thespecimens should be opaque, uniform in color, plane, anduniform in texture. The specimens should be
20、relatively perma-nent, and capable of being cleaned. Preferred sizes of speci-mens for visual evaluation are given in Practice D 1729, thespecific size being governed by the use of the specimens.7. Procedure7.1 Selection and Specification of Color and Gloss Stan-dard:7.1.1 Select a standard in accor
21、dance with Practice D 3964that is preferably the same type of material as the specimens tobe evaluated for color or gloss, or both. Prepare, in sufficientquantity, secondary standards in accordance with GuideD 5531 that are representative of the desired color and gloss, inthe permanent material. Sta
22、ndards should have the samespectral characteristics as the manufactured product. This isusually accomplished by use of the same colorant composition,incorporated in the same manner into the same material. Thestandard should have the same texture as the manufacturedproduct.7.1.1.1 In order to obtain
23、a permanent record, use PracticeE 805 and either Test Method E 1331 or Test Method E 1349 tocorrectly identify the instrumental measurement method. Mea-sure the color in accordance with Practices E 1164 and E 805.Report the color as described in Practice E 308. Do this even ifthe standard is texture
24、d. (If the standard is textured, note thetexture orientation during measurement.) The variability of themeasurements due to texture may be reduced by following therecommendations outlined in Practice E 1345.7.1.1.2 Visual Color AssessmentUse Guide E 1499 toselect an observer for the assessment. Asse
25、ss and specify thecolor in terms of a color system described in Practices D 1535,E 1360, or E 1541.7.1.1.3 Measure the gloss in accordance with Test MethodD 523, or evaluate it in accordance with Test Method D 4449.7.1.1.4 Employ photography for permanently recording theappearance of the surface tex
26、ture (see Practice E 312). WhilePractice D 3134 does not deal with texture tolerances orspecifications, it should be recognized that significant differ-ences in surface texture between standard and test specimenssignificantly affect both color and gloss, whether examinedvisually or instrumentally. I
27、n the case of visual evaluation ofthe effect of color and gloss, differences can be minimized bystrict adherence to recommended illuminating and viewinggeometry (see Practice D 1729).7.2 Selection and Specification of Color Tolerances:7.2.1 The purchaser and the seller shall agree on colortolerances
28、 with respect to a previously selected standard and onthe color scales in which they are expressed. Selection of themagnitude and direction of color tolerances shall be based oncareful consideration of all applicable factors. For example,tolerances may be selected on the basis of perceptibility of t
29、hemagnitude of color difference, rejection of or closer limits oncertain directions of color difference, and costs of controllingthe magnitude and direction of color difference. Recommen-dations on color scales appear in CIE Publication No. 15.2 andPractice E 308.7.2.1.1 Express color differences be
30、tween the specimen andthe standard in terms of a set of three independent parameters.The CIE 1976 L*a*b* (CIELAB) approximately uniform colorspace and color difference equations have been recommendedfor use by the International Commission on Illumination (CIE).See Practice D 2244 and Practice E 308.
31、 While this colormetric (CIELAB) is convenient for expressing color differ-ences, it must be understood that a given calculated colordifference in one region of color space may not represent thesame visual difference in other regions of color space.7.2.2 Gloss differences can affect instrumental mea
32、surementof color differences. Large gloss differences between visuallyidentical colors can cause their color measurements to exhibitlarger color differences than in fact exist. When using historicaldata to establish color tolerances, exercise care to limit thespecimens to those that have quite simil
33、ar gloss values. Whenestablishing gloss tolerances, be aware that changes in glossvalues may have an effect upon color measurements.7.2.3 When color difference formulae are used in practice, itis often desirable to identify the components of color differ-ence, in terms of correlates of lightness, hu
34、e, and perceivedchroma (saturation). It is also desirable to express colorspecifications in terms of such correlates. The CIE terminologyappropriate to this usage is CIE 1976 lightness, CIE 1976hue-angle, hab, and CIE 1976 chroma, C*ab. Refer to Practice3Available from The U.S. National Committee of
35、 the CIE (InternationalCommission on Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants,Inc., 7 Pond St., Salem, MA 01970.D 3134 97 (2003)2D 2244 and Practice E 308 for equations and definitions. TheCIELAB 1976 hue-angle and chroma are illustrated in Fig. 1.7.2.4 The CIELAB opponent-color
36、 red-green coordinate a*,and the yellow-blue coordinate b* are defined in PracticeD 2244 and Practice E 308.7.2.5 Graphical Interpretation of Historical Data:7.2.5.1 Color tolerances can be determined from a graphicalinterpretation of historical data (batches accepted, rejected, orconsidered borderl
37、ine). Fig. 2 (a) and Fig. 3(b) show plots ofspecimens rated by multiple observers with respect to how wellthey match a standard, along with figures defining the toler-ances. To illustrate the principle recommended: (1) rate anumber of specimens for acceptability, (2) plot them, and (3)prepare to dra
38、w the tolerance figure dictated by the data.7.2.5.2 In such cases it is customary to plot the hue angle ofthe standard by drawing a line from the origin (0, 0) throughthe standard color on the a*b* plot. This line of constant huebecomes the major axis. Similarly, a line perpendicular to theconstant-
39、hue line and passing through the standard color is aline of constant chroma (or saturation) and becomes the minoraxis of the ellipse, if the data plot indicates the ellipse shouldbe symmetrical around the standard color. These lines assist indrawing the tolerance ellipse, Fig. 2(a).7.2.5.3 To determ
40、ine lightness tolerances it is necessary toplot the data for the same colors on a graph showing L* alongwith either a* and b*, and draw a tolerance ellipse as in Fig.3(b). The choice between a* and b* is dictated by which ofthese attributes cover the greater range.7.2.5.4 The scales on Fig. 2(a) and
41、 Fig. 3(b) are changedfrom absolute values (L*, a*, b*) into color difference values(DL*, Da*, Db*) as shown .7.2.6 When tolerances for each color attribute (hue, light-ness, and saturation or chroma) are symmetrical in the plus andminus directions, the graphical representation is a regulargeometric
42、 figure that can be represented mathematically, as bythe equation for an ellipse or an ellipsoid. It is also common torepresent color tolerances by a set of six points: light and darklimits, low and high saturation limits, and two adjacent huelimits. Such representation may involve some sacrifice in
43、accuracy of the tolerance specification and should be used withcare.7.2.7 In general, color tolerances will not be symmetricallylocated in all directions about the standard color in any colorspace. (see Fig. 2(a) and Fig. 3(b). However, in someinstances the asymmetry may be small enough that the col
44、ortolerances may be represented by a single, overall colordifference (DE) that represents the radius of a sphere about thestandard in color space.7.2.8 Finally, there are many deviations from the regulargeometric figures described in 7.2.6 and depicted in Fig. 2(a)and Fig. 3(b). The nongreen and non
45、yellow biases mentionedin the introduction are but two of these. For example, thetolerance figure may not be regular; perhaps it will be an ovoidinstead of an ellipse; its major axis may deviate from thedirection of constant hue; and the standard color may be farfrom its center. Frequently when it i
46、s necessary to set colortolerances, the amount of historical accept-reject data will betoo modest for this purpose. It is therefore necessary to monitortolerances, once set, to ensure that they appropriately addressthe color quality control requirement.7.2.9 When tolerance standards are prepared to
47、illustrate thecolor in the hue, lightness, and saturation or chroma attributesof color space and to allow visual interpretation of theconformity of color, inspection should be under specified lightsources following the recommendations in Practice D 1729.Gonioapparent coatings or materials require sp
48、ecial method-ologies for viewing and measurement.7.3 Selection and Specification of Gloss Tolerances:7.3.1 The gloss tolerances around the gloss of the standardmay be expressed in gloss units (See Test Method D 523) or asa percent.7.3.2 With few exceptions, the visual gloss tolerance will besymmetri
49、cal around the nominal value of the standard. It willbe necessary to determine experimentally the instrumentalreadings that correspond to the required visual differences.7.3.3 When the gloss desired is at or near the maximum orminimum gloss attainable, it is customary to specify a singlegloss reading and the direction in which the data may departfrom it. For example, for a very high gloss requirement, onemight specify “80 units minimum.” Similarly, for a very lowgloss the specification might read “3 units maximum,” with themeasurement geometry being indicated in each case.7.3.4 If
