1、Designation: D 7195 06Standard GuideProtocol for Setting Color Specifications for a Material1This standard is issued under the fixed designation D 7195; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n
2、umber 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 guide leads the user through the process for settinga color tolerance for a product or material. It points to theappropriate ASTM
3、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 partiesinvolved.1.3 This
4、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
5、.1 ASTM Standards:2D 523 Test Method for Specular GlossD 1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque MaterialsD 2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesD 3134 Practice fo
6、r Establishing Color and Gloss Toler-ancesD 3964 Practice for Selection of Coating Specimens forAppearance MeasurementsD 4086 Practice for Visual Evaluation of MetamerismD 4449 Test Method for Visual Evaluation of Gloss Differ-ences Between Surfaces of Similar AppearanceD 5531 Guide for Preparation,
7、 Maintenance, and Distribu-tion of Physical Product Standards for Color and Geomet-ric Appearance of CoatingsE 179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Properties ofMaterialsE 253 Terminology Relating to Sensory Evaluation of Ma-terials and Produc
8、tsE 284 Terminology of AppearanceE 308 Practice for Computing the Colors of Objects byUsing the CIE SystemE 805 Practice for Identification of Instrumental Methods ofColor or Color-Difference Measurement of MaterialsE 1164 Practice for Obtaining Spectrometric Data forObject-Color EvaluationE 1345 Pr
9、actice for Reducing the Effect of Variability ofColor Measurement by Use of Multiple MeasurementsE 1347 Test Method for Color and Color-Difference Mea-surement by Tristimulus (Filter) ColorimetryE 1499 Guide for Selection, Evaluation, and Training ofObserversE 1708 Practice for Electronic Interchang
10、e of Color andAppearance DataE 1808 Guide for Designing and Conducting Visual Experi-mentsE 2214 Practice for Specifying and Verifying the Perfor-mance of Color-Measuring Instruments2.2 CIE PublicationsCIE 15:2004 Colorimetry, 3rdedition33. Terminology3.1 DefinitionsFor definitions of terms related
11、to thisguide see Terminology E 253 and Terminology E 284.4. 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 of
12、 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 D1.26 on Optical Properties.Current edition approved Apri
13、l 1, 2006. Published April 2006.2For 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 U.S. National
14、 Committee of the CIE (International Commissionon Illumination), C/o Thomas M. Lemons, TLA-Lighting Consultants, Inc., 7 PondSt., Salem, MA 01970.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.3 It begins the process of setting a
15、tolerance by firstselecting a standard or target color for the material, includingthe 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
16、materials due to color is a common andexpensive occurrence, and it is useful for a customer 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 com
17、mon reason stated for rejection 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 a color specificationwith an associated tolerance. Then the producer can beconfident that if they
18、 supply material that falls within the colorspecification, the customer will accept the 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 th
19、rough the decision-making process and point 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 m
20、ust first decidewhether there will be a 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 differ
21、ences. Additionally, thevisual abilities 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 E 1499 pro-vides more detailed informatio
22、n.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 alsooccurred in the equations and software programs for evaluating
23、color 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 difference calculations are widelyused throughout industry. See Practi
24、ce D 2244 for more detailson the 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 boxes. However, it is now possible and desirable to useelliptical tolerancing.7.4 In
25、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 lessthan a perceptible difference, then instrumental methods willhave to be used. Both the producer and the customer shouldre
26、fer to Practice E 2214.7.5 While the goal is to have an agreed color specificationwith an acceptable tolerance for both the producer and thecustomer, each party must carefully consider their position.The producer must know that they are able to control the colorin production to the level specified w
27、ithout excessive waste andundue loss. The customer must be assured that the tolerance issuch 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 or
28、der to compare the color of a testmaterial to a target material, either visually or instrumentally,the other aspects of appearance should be the same, or assimilar as possible. Test Method D 4449 covers the visualevaluation of gloss, while Test Method D 523 covers instru-mental gloss measurement.7.7
29、 Since it is not always possible to have all appearanceparameters the same or even if they are 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
30、trying to have instrumental readings that correlate with thevisual appearance of a material, one needs to establish consis-tency between the visual situation and the instrumental set up.Guide E 179 discusses the terminology and instrumentation forevaluating appearance characteristics. Some of the co
31、nsider-ations when choosing the geometry of evaluation are:7.7.1 What are your internal needs 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
32、texture of the standard andspecimen are different, do you want specimens gloss or grainlevels 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 th
33、e criterion for acceptance. Formany users the final criterion is visual acceptance, that is,visual 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 a
34、greed 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 point,7.8.1.2 Reduced costs of making and ma
35、intaining masterstandards,7.8.1.3 Easy to communicate an absolute number throughe-mail or voicemail, and7.8.1.4 Faster; and fewer subjective calls.D71950627.8.2 Some of the disadvantages of using a digital standardare:7.8.2.1 For best consistency, both supplier and customermust have the same instrum
36、ent,7.8.2.2 There is no physical standard available to use for avisual comparison,7.8.2.3 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
37、 orslightly fail.7.9 Maintaining master and working physical standards isdiscussed in detail in Guide D 5531. 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 o
38、ptimal condition (in the dark, away from heatsources, chemical fumes, direct sun-rays, etc.) 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
39、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 a signed-off (working master) part androutinely check the difference between the master and theworking master to ensure
40、 that neither has changed.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 measurements and visualevaluations to be different.7.10 All measured values have an uncertai
41、nty associatedwith the measurement. In order to reduce the confidence limitsassociated with 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
42、 is described inPractice E 1345.7.11 It is best if the standard and the trial material can bemeasured at the same time, on the same equipment by the sameoperator. This is the best way to eliminate production, test andraw material effects.8. Procedure for Setting a Tolerance8.1 Section 8 gives the st
43、eps 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) standardthat represents the required color and to assure that all the(working) standards used in the control program match thatcolor within a ver
44、y small tolerance. See Practice D 3964.Additionally, a program should be established to monitor thecolor quality of those working standards. See Guide D 5531.Sample preparation is a very important issue. The surfacecharacteristics and texture are important considerations andshould be consistent.NOTE
45、 2For coatings one might spray (using a specific procedure) ordraw down the specimens. For 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
46、 the original formulation.TABLE 1 Summary of ASTM Standard UsedColor Specification Objective ASTM Standard Reference1. Physical Standard Measurement D 3964 Practice for Selection ofCoating Specimens forAppearance MeasurementsD 5531 Guide for Preparation,Maintenance, and Distribution ofPhysical Produ
47、ct Standards forColor and Geometric Appearanceof CoatingsTest for Metamerism D 4086 Practice for VisualEvaluation of Metamerism2. Establishing a tolerance:using historical samples D 1729 Practice for VisualAppraisal of Colors and ColorDifferences of Diffusely-IlluminatedOpaque Materialsusing experim
48、ents E 1808 Guide for Designing andConducting Visual Experimentsmeasure specimens E 1164 Practice for ObtainingSpectrometric Data for Object-Color EvaluationE 1347 Test Method for Colorand Color-Difference Measurementby Tristimulus (Filter) ColorimetryE 308 Practice for Computingthe Colors of Object
49、s by Using theCIE Systemestablishing tolerance D 3134 Practice for EstablishingColor and Gloss Tolerances3. Produce Color Evaluation Report E 805 Practice of Identification ofInstrumental Methods of Color andColor-Difference Measurement ofMaterialsE 1708 Practice for ElectronicInterchange of Color andAppearance DataFIG. 1 Elliptical vs Box TolerancingD71950638.2.2 On occasion the target color cannot be used as thestandard because it is not the same material or not made fromthe formulation that will be used in production. In this case, astandard should be prod
