1、Designation: D7195 16aStandard Guide forSetting Object Color Specifications1This standard is issued under the fixed designation D7195; 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 parenthes
2、es indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide leads the user through a process for estab-lishing color specifications, including the target color andallowable tolerances. It refers to the a
3、ppropriate ASTM stan-dards that more thoroughly describe each step of the processbeginning with expectations, encompassing caveats within theprocess and finally concluding with reporting.1.2 This guide does not suggest numerical values for toler-ances. These values must be agreed upon by the parties
4、involved.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 prior to use.2. Ref
5、erenced Documents2.1 ASTM Standards:2D523 Test Method for Specular GlossD1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque MaterialsD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD31
6、34 Practice for Establishing Color and Gloss TolerancesD3964 Practice for Selection of Coating Specimens forAppearance MeasurementsD4086 Practice for Visual Evaluation of MetamerismD4449 Test Method for Visual Evaluation of Gloss Differ-ences Between Surfaces of Similar AppearanceD5531 Guide for Pre
7、paration, Maintenance, and Distributionof Physical Product Standards for Color and GeometricAppearance of CoatingsE179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Propertiesof MaterialsE284 Terminology of AppearanceE308 Practice for Computing the Colors
8、of Objects by Usingthe CIE SystemE805 Practice for Identification of Instrumental Methods ofColor or Color-Difference Measurement of MaterialsE1164 Practice for Obtaining Spectrometric Data for Object-Color EvaluationE1345 Practice for Reducing the Effect of Variability ofColor Measurement by Use of
9、 Multiple MeasurementsE1347 Test Method for Color and Color-Difference Mea-surement by Tristimulus ColorimetryE1499 Guide for Selection, Evaluation, and Training ofObserversE1708 Practice for Electronic Interchange of Color andAppearance DataE1808 Guide for Designing and Conducting Visual Experi-men
10、tsE2214 Practice for Specifying and Verifying the Perfor-mance of Color-Measuring InstrumentsE2867 Practice for Estimating Uncertainty of Test ResultsDerived from Spectrophotometry2.2 CIE Publications:CIE Publication 015 Colorimetry33. Terminology3.1 DefinitionsFor definitions of terms related to th
11、isguide see Terminology E284.4. Summary of Guide4.1 This guide describes the process for establishing colorspecifications for a material, including the decision as towhether this specification will be based on visual or instrumen-tal methods.4.2 General considerations of appearance, evaluation ofobs
12、ervers, and measurement techniques are included.4.3 It begins the process of setting a tolerance by firstselecting a standard or target color for the material, includingthe production, measurement, and storage of that target.1This guide is under the jurisdiction of ASTM Committee E12 on Color andApp
13、earance and is the direct responsibility of Subcommittee E12.04 on Color andAppearance Analysis.Current edition approved Aug. 1, 2016. Published September 2016. Originallyapproved in 2006. Last previous edition approved in 2016 as D7195 16. DOI:10.1520/D7195-16A.2For referenced ASTM standards, visit
14、 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 (International Commission on Illumination), http:/www.cie.co.at or http:/.Copy
15、right ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.4 It next identifies methods to establish acceptable colortolerances.4.5 Finally, it discusses reporting techniques.5. Significance and Use5.1 The rejection of materials due to color is a
16、common andexpensive occurrence, and it is useful for a customer andproducer to set color specifications with an associated tolerancebefore the transaction. This guide discusses the concept anddetails the ASTM standards to be used in the process.6. Introduction6.1 A common reason stated for rejection
17、 of goods ormaterials is that the product color does not meet expectations.The best way to avoid the problem of returned goods ormaterials because of color is to establish color specificationswith associated tolerances. Then the producer can be confidentthat if they supply material that falls within
18、 the specification,the customer will accept the product.6.2 To supply product within specification consistently re-quires production that is under statistical process control, and aprogram of color measurement and evaluation.6.3 This guide will lead the user through the decision-making process and p
19、oint to the appropriate ASTM standardsthat are pertinent to each step. It will include the discussionpoints on which the two parties must agree and will providecaveats for various options selected.7. General Discussions7.1 In setting up the specification, one must first decidewhether there will be a
20、 visual or instrumental evaluation of thecolor. Observers have different color perception skills.Ahighlytrained colorist can see very minute color differences whereasthe more casual observer or color-anomalous observer wouldnot normally detect very small differences. Additionally, thevisual abilitie
21、s or perception levels of observers, may varybetween persons and over time within an individual. Thus if thecolor of the material will be evaluated visually, we must ensureconsistent conditions for the evaluation. Guide E1499 providesdetailed information about the selection of observers. GuideE1808
22、provides guidance on how to conduct critical visualobservations.7.2 Numerous advances have occurred in both the accuracyand repeatability of color measurement instruments. However,there may still be considerable differences between instrumentsof different make, type, and geometry. Advances have also
23、occurred in the equations and software programs for evaluatingcolor and color quality control. It is not uncommon for thespecification to be set numerically and evaluated by instrumen-tal measurement, but then the question “what should mytolerance be?” must be resolved.7.3 A number of color differen
24、ce calculations are widelyused throughout industry. See Practice D2244 for more detailson color difference and color tolerance equations. Whichcolor-difference metric will be used should be agreed upon bythe two parties involved. For years, color tolerances were setup as rectangular tolerancing. In
25、some industries the phrase“box tolerancing” is the accepted terminology. However,elliptical tolerancing is preferred.7.4 In most cases, the limits of acceptability will be greaterthan a just perceptible difference, but in some cases, thetolerance may be less than a perceptible difference. If it is l
26、essthan a perceptible difference, then instrumental methods shouldbe used. Both the producer and the customer should refer toPractice E2214.7.5 While the goal is to have an agreed color specificationwith an acceptable tolerance for both the producer and thecustomer, each party must carefully conside
27、r their position.The producer should be assured that they are able to control thecolor in production to the level specified without excessivewaste and undue loss. The customer should be assured that thetolerance is such that the color of the goods will be acceptable.7.6 Color is one aspect of the ap
28、pearance of a material.Other appearance parameters include, but are not limited to,gloss, haze, and texture. In order to compare the color of a testmaterial to a target material, either visually or instrumentally,all aspects of appearance should be the same, or as similar aspossible. Test Method D44
29、49 covers the visual evaluation ofgloss difference, while Test Method D523 covers instrumentalgloss measurement.7.7 It is important to use established and consistent viewingconditions. These include the illumination, the positioning ofthe standard and specimen, and the receptor system, whetherhuman
30、or instrumental. If one is trying to have instrumentalreadings that correlate with the visual appearance of a material,one needs to establish consistency between the visual situationand the instrumental set up. Guide E179 discusses the termi-nology and instrumentation for evaluating appearance chara
31、c-teristics. Some of the considerations when choosing the geom-etry of evaluation are:7.7.1 What are ones internal needs such as formulation,quality control, auditing, trouble shooting?7.7.2 What are ones customers specifications and needs?7.7.3 Does one want the numbers to match visual evalua-tion?
32、7.7.4 If the gloss or surface texture of the standard andspecimen are different, does one want specimens gloss orgrain levels to produce the same colorimetric values as thestandard when measured?7.7.5 Does one want to deal with a small or large processwindow?7.8 It is important to have the producer
33、and the customeragree on the target color and the criteria for acceptance. Formany users the final criterion is visual acceptance, that is,visual color is the final deciding factor. However, some usershave demonstrated that more consistent product quality isobtained instrumentally, avoiding the “fin
34、al visual inspection.”Once the color is agreed upon, then one should decide whetherto use visual or objective standards and tolerances.7.8.1 Some of the advantages of using a digital standard are:7.8.1.1 Both supplier and customer have the same absolutenumbers to judge against, the same starting poi
35、nt,D7195 16a27.8.1.2 Reduced costs of making and maintaining masterstandards,7.8.1.3 Easy to communicate an absolute numberelectronically, and7.8.1.4 Faster; and fewer subjective calls.7.8.2 Some of the disadvantages of using a digital standardare:7.8.2.1 For best consistency, both supplier and cust
36、omermust have the same instrument,7.8.2.2 There is no physical standard available to use for avisual comparison,7.8.2.3 The risk increases if different materials, technologiesor different suppliers are used, and7.8.2.4 There is less opportunity to ship acceptable-colorproduct that matches but have n
37、umbers on the borderline orslightly greater than the numerical tolerance.7.9 Maintaining master and working physical standards isdiscussed in detail in Guide D5531. However, some importantaspects are repeated here.7.9.1 Store master standards in a suitable protectivematerial, under appropriate tempe
38、rature and humidity condi-tions for the material to keep it in optimal condition (in thedark, away from heat sources, chemical fumes, direct sun-rays,etc.) and only remove when necessary to verify new workingstandards.7.9.2 Maintain multiple working standards, with only one incirculation at a given
39、time.7.9.3 Handle master standards with lint-free gloves.7.9.4 Record dates on all master and working standardswhen they are approved and by whom.7.9.5 Frequently inspect working standards for scratches,changes in gloss or color.7.9.6 Match to an approved (working master) part androutinely check the
40、 color difference between the master and theworking master to ensure that the working standard has notchanged.NOTE 1Once the working master has been established, it is desirableto use this rather than going back to the master because reference to themaster can open the door for instrumental measurem
41、ents and visualevaluations to be different.7.10 All measured values have an uncertainty associatedwith the measurement. Estimate the uncertainty of test resultsusing Practice E2867. To reduce the confidence limits associ-ated with color or color-difference measurements statisticalanalysis of the res
42、ults of multiple measurements on a singlespecimen or the measurement of multiple specimens can beused. This procedure is described in Practice E1345.7.11 It is best if the standard and the trial material can bemeasured at the same time, on the same equipment by the sameoperator. Single operator prec
43、ision is the best way to estimateproduction, test and raw material effects.8. Procedure for Setting a Tolerance8.1 Section 8 gives the steps for setting a tolerance. Table 1summarized the ASTM Standards referenced for each of thesesteps.8.2 The first step is to establish a physical (master) standard
44、that represents the required color and to assure that all the(working) standards used in the control program match thatcolor within a very small tolerance. See Practice D3964.Additionally, a program should be established to monitor thecolor quality of those working standards. See Guide D5531.Sample
45、preparation is a very important issue. The surfacecharacteristics and texture are important considerations andshould be consistent.NOTE 2For coatings one might spray (using a specific procedure) ordraw down the specimens. For other materials use techniques appropriatefor those materials.8.2.1 Ideall
46、y all the standards should be of the same materialand texture as the product to be supplied, using the samepigments and dyes as used in the original formulation.8.2.2 On occasion the target color cannot be used as thestandard because it is not the same material or not made fromthe formulation that w
47、ill be used in production. In this case, astandard should be produced from the material to be supplied.The producer and the customer should agree in writing that thisspecimen is an acceptable production standard. Metamerismbetween the target color and the standard should be minimized.The metamerism
48、should be evaluated either instrumentally orvisually. Practice D4086 describes the techniques for doing thisvisually. Comparison of the color difference between the targetand standard calculated under different illuminants provides aninstrumental measure of metamerism.TABLE 1 Summary of ASTM Standar
49、d UsedColor Specification Objective ASTM Standard Reference1. Physical Standard Measurement D3964 Practice for Selection ofCoating Specimens for Appear-ance MeasurementsD5531 Guide for Preparation,Maintenance, and Distribution ofPhysical Product Standards forColor and Geometric Appearanceof CoatingsTest for Metamerism D4086 Practice for Visual Evalu-ation of Metamerism2. Establishing a tolerance:Using historical samples D1729 Practice for Visual Ap-praisal of Colors and Color Differ-ences of Diffusely-IlluminatedOpaque MaterialsUsing experiments E1
