1、Designation: D7195 06 (Reapproved 2012)Standard Guide forProtocol for Setting Color Specifications for a Material1This 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 o
2、f 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 guide leads the user through the process for settinga color tolerance for a product or material. It points to t
3、heappropriate ASTM standards that affect each step of theprocess. It includes the discussion points on which the twoparties must agree and provides caveats for various optionsselected.1.2 This guide does not suggest numerical values for toler-ances. These values must be agreed upon by the two partie
4、sinvolved.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. Re
5、ferenced 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 ColorCoordinatesD3
6、134 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 Pr
7、eparation, Maintenance, and Distributionof Physical Product Standards for Color and GeometricAppearance of CoatingsE179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Propertiesof Materials (Withdrawn 2012)3E253 Terminology Relating to Sensory Evaluation of
8、 Mate-rials and ProductsE284 Terminology of AppearanceE308 Practice for Computing the Colors 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
9、EvaluationE1345 Practice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple MeasurementsE1347 Test Method for Color and Color-Difference Mea-surement by Tristimulus ColorimetryE1499 Guide for Selection, Evaluation, and Training ofObserversE1708 Practice for Electronic Inte
10、rchange of Color andAppearance DataE1808 Guide for Designing and Conducting Visual Experi-mentsE2214 Practice for Specifying and Verifying the Perfor-mance of Color-Measuring Instruments2.2 CIE PublicationsCIE 15:2004 Colorimetry, 3rdedition43. Terminology3.1 DefinitionsFor definitions of terms rela
11、ted to thisguide see Terminology E253 and Terminology E284.4. Summary of Guide4.1 This guide describes the process for establishing a colorspecification for a material, including the decision as towhether this specification will be based on visual or instrumen-tal methods.4.2 General considerations
12、of appearance, evaluation ofobservers, and measurement techniques are included.1This guide is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.26 on Optical Properties.Current edition approved J
13、une 1, 2012. Published July 2012. Originally approvedin 2006. Last previous edition approved in 2006 as D7195 06. DOI: 10.1520/D7195-06R12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume
14、 information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.4Available from U.S. National Committee of the CIE (International Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultan
15、ts, Inc., 7 PondSt., Salem, MA 01970, http:/www.cie-usnc.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.3 It begins the process of setting a tolerance by firstselecting a standard or target color for the material, includingthe
16、production, measurement, and storage of that target.4.4 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 common andexpensive occurrence, and it is useful for a cus
17、tomer andproducer to set a color specification with an associated toler-ance before the transaction. This guide discusses the conceptand details the ASTM standards to be used in the process.6. Introduction6.1 A common reason stated for rejection of goods ormaterials is that the product color does no
18、t meet expectations.The best way to avoid the problem of returned goods ormaterials because of color is to establish a color specificationwith an associated tolerance. Then the producer can beconfident that if they supply material that falls within the colorspecification, the customer will accept th
19、e color of the product.6.2 To supply color within specification consistently re-quires production that is in statistical control, and a program ofcolor measurement and evaluation6.3 This guide will lead the user through the decision-making process and point to the appropriate ASTM standardsthat are
20、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 visual or instrumental evaluation of thecolor.
21、 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 abilities or perception levels of observers, may varybe
22、tween 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 providesmore detailed information.7.2 Numerous advances have occurred in both the accuracyand repeatability of color meas
23、urement instruments. However,there may still be considerable differences between instrumentsof different make, type, and geometry. Advances have alsooccurred in the equations and software programs for evaluatingcolor and color quality control. It is not uncommon for thespecification to be set numeri
24、cally and evaluated by instrumen-tal measurement, but then the question “what should mytolerance be?” must be resolved.7.3 A number of color difference calculations are widelyused throughout industry. See Practice D2244 for more detailson the color difference and color tolerance equations. Whichcolo
25、r-difference metric will be used should be agreed upon bythe two parties involved. For years, color tolerances were setup as boxes. However, it is now possible and desirable to useelliptical tolerancing.7.4 In most cases, the limits of acceptability will be greaterthan a just perceptible difference,
26、 but in some cases, thetolerance may be less than a perceptible difference. If it is lessthan a perceptible difference, then instrumental methods willhave to be used. Both the producer and the customer shouldrefer to Practice E2214.7.5 While the goal is to have an agreed color specificationwith an a
27、cceptable tolerance for both the producer and thecustomer, each party must carefully consider their position.The producer must know that they are able to control the colorin production to the level specified without excessive waste andundue loss. The customer must be assured that the tolerance issuc
28、h that the color of the goods will be functionally acceptable.7.6 Color is one aspect of the appearance 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 instrum
29、entally,the other aspects of appearance should be the same, or assimilar as possible. Test Method D4449 covers the visualevaluation of gloss, while Test Method D523 covers instru-mental gloss measurement.7.7 Since it is not always possible to have all appearanceparameters the same or even if they ar
30、e the same, it isimportant to use established viewing conditions. These includethe illumination, the positioning of the standard and specimen,and the receptor system, whether human or instrumental. If oneis trying to have instrumental readings that correlate with thevisual appearance of a material,
31、one needs to establish consis-tency between the visual situation and the instrumental set up.Guide E179 discusses the terminology and instrumentation forevaluating appearance characteristics. Some of the consider-ations when choosing the geometry of evaluation are:7.7.1 What are your internal needs
32、such as formulation,quality control, auditing, trouble shooting?7.7.2 What are your customers specifications and needs?7.7.3 Do you want the numbers to match visual evaluation?7.7.4 If the gloss or surface texture of the standard andspecimen are different, do you want specimens gloss or grainlevels
33、to produce the same colorimetric values when mea-sured?7.7.5 Do you want to deal with a small or large processwindow?7.8 It is important to have the producer and the customeragree on the target color and the criterion for acceptance. Formany users the final criterion is visual acceptance, that is,vi
34、sual appearance is the final deciding factor. However, someusers have demonstrated that more consistent product quality isobtained instrumentally, avoiding the “final visual inspection.”Once the color is agreed upon, then one should decide whetherto use visual or objective standards and tolerances.7
35、.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 point,D7195 06 (2012)27.8.1.2 Reduced costs of making and maintaining masterstandards,7.8.1.3 Easy to communicate an absolute number throug
36、he-mail or voicemail, 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 customermust have the same instrument,7.8.2.2 There is no physical standard available to use for avisual comparison,7.8.2
37、.3 It is especially risky if different materials, technolo-gies or different suppliers are used, and7.8.2.4 There is less opportunity to ship acceptable-colorproduct that matches but have numbers on the borderline orslightly fail.7.9 Maintaining master and working physical standards isdiscussed in d
38、etail in Guide D5531. However, some importantaspects are repeated here.7.9.1 Store masters in a suitable protective material, underappropriate temperature and humidity conditions for the mate-rial to keep it in optimal condition (in the dark, away from heatsources, chemical fumes, direct sun-rays, e
39、tc.) and only removewhen necessary to verify new working standards.7.9.2 Maintain multiple working standards, with only one incirculation at a given 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
40、 Frequently inspect working standards for scratches,changes in gloss or color.7.9.6 Match to a signed-off (working master) part androutinely check the difference between the master and theworking master to ensure that neither has changed.NOTE 1Once the working master has been established, it is desi
41、rableto use this rather than going back to the master because reference to themaster can open the door for instrumental measurements and visualevaluations to be different.7.10 All measured values have an uncertainty associatedwith the measurement. In order to reduce the confidence limitsassociated w
42、ith color or color-difference measurements ofcolored materials, statistical analysis of the results of multiplemeasurements on a single specimen or the measurement ofmultiple specimens can be used. This procedure is described inPractice E1345.7.11 It is best if the standard and the trial material ca
43、n bemeasured at the same time, on the same equipment by the sameoperator. This is the best way to eliminate production, test andraw 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
44、thesesteps.8.2 The first step is to establish a physical (master) standardthat 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 mo
45、nitor thecolor quality of those working standards. See Guide D5531.Sample 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
46、other materials use techniques appropriatefor those materials.8.2.1 Ideally 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
47、because it is not the same material or not made fromthe formulation that will 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. Metamerismbet
48、ween the target color and the standard should be minimized.The metamerism 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 pro
49、vides aninstrumental measure of metamerism.8.3 The most accurate way to establish tolerances is to havea wide range of samples that have been visually evaluated asacceptable or unacceptable when compared to the standard.These can be historical samples taken from earlier productionTABLE 1 Summary of ASTM Standard 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 an
