1、Designation: D 3964 04Standard Practice forSelection of Coating Specimens for AppearanceMeasurements1This standard is issued under the fixed designation D 3964; 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.1. Scope1.1 This practice provides a guide to selection of specimensfor appearance measurement as well as a discussion of factorsto be cons
3、idered in their preparation for measurement. Stan-dardized selection and presentation procedures will assist inachieving agreement between evaluations carried out in differ-ent laboratories as well as helping to achieve better correlationsbetween visual evaluations and instrumental measurements.NOTE
4、 1This standard is not a practice for preparation of test panels ofcoatings; see Practices D 823.1.2 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
5、practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsE 284 Terminology of Appearance3. Terminology3.1 Definitions:3.1.
6、1 For definitions of terms used in this practice, refer toTerminology E 284.4. Significance and Use4.1 Many of the specimens that are regularly submitted tomeasurement depart in some degree from the ideal require-ments. For this reason instrumental readings are affectedimportantly by the manner in w
7、hich specimens are selected andpresented for measurement. Reproducible measurements arefacilitated by standardization and control of test conditions.5. General Requirements5.1 SelectionIn making appearance measurements it isimportant that the specimens selected be representative of thematerial of in
8、terest. Once selected, the specimens must becarefully examined to determine if they are suitable formeasurement, and if not, they must be cleaned or otherwiseprepared. Careful attention to these factors is necessary if themeasurements are to be valid.5.2 Specimen SizeThe minimum size is dictated by
9、thesize of the specimen port of the instrument to be used formeasurement. When an instrument provides a choice of speci-men port sizes, use the largest port that can be completelycovered by the specimen. A large measured area helps tominimize the effect of any small area nonuniformity and istherefor
10、e more likely to provide results that agree with theinvoluntary averaging that takes place when specimens areobserved visually. In addition, a large specimen also permitsthe operator to make measurements on several areas of thespecimen when desired, thereby providing further specimenaveraging.5.3 Op
11、acityFor determination of gloss or color, an opaquespecimen shall be selected whenever possible. When thespecimen is translucent or transparent, the following practicesshall be implemented:5.3.1 For Gloss EvaluationThe specimen shall preferablybe sufficiently thick that a secondary reflection from t
12、he backor second surface of the specimen cannot enter the receptoroptics of the glossmeter. When thin transparent specimensmust be measured, adopt one of the following procedures:5.3.1.1 Back the specimen with a light-absorbing materialof the same refractive index as the specimen, and in opticalcont
13、act with it.5.3.1.2 Use an agreed-upon specimen thickness, includingcoating and substrate, and place a black backing behind thespecimen.5.3.2 For Color EvaluationThe choice of backing of evenslightly translucent specimens will affect their measurement.Use the most applicable of the backing technique
14、s that follow.In each case it is essential that the backing material and colorbe reproducible, stable, and durable for reliable results.5.3.2.1 Back the specimen with the same material withwhich it will be backed in its intended use.5.3.2.2 Back the specimen with identical or similar material.1This
15、practice 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 July 1, 2004. Published July 2004. Originally approvedin 1980. Last previous editio
16、n approved in 1998 as D 3964 80 (1998).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.1Copyright ASTM Intern
17、ational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.3.2.3 Back the specimen with a neutral material whoseluminous reflectance is essentially the same as that of thespecimen being evaluated.5.3.2.4 Back the specimen with a black surface such as apainted pane
18、l or black glass.5.3.2.5 Back the specimen with a white backing of knownreflectance.6. Physical Properties6.1 The specimen shall preferably be rigid and have a planesurface. Specimens of thin, flexible material that can bulge orsag when presented to an instrument require special holdingequipment. Wh
19、en the specimen is moderately flexible, a planesurface may be achieved by pressing the specimen against theinstrument with a flat, rigid object. The pressing techniquemust be reproducible. A vacuum plate or specially designedclamping device has proven satisfactory in some applications.Note that spec
20、imens coated on thin plastic film or paper maytrap air between the specimen and the holder (vacuum plate orclamping device) causing the specimen to billow (blister)resulting in erroneous readings.6.2 Surface TextureSome coatings have pronounced sur-face texture, making it desirable to rotate a speci
21、men in its ownplane. Those with marked directionality, usually due to theproduction process, will have different values when measuredin different directions. Good practice dictates that measure-ments be made with the plane of measurement of the instru-ment both parallel to as well as perpendicular t
22、o the processdirection.7. Cleaning of Specimens7.1 The specimen shall be clean. There should be no dirt,dust, oil or foreign material on the surface that will affect theinstrumental evaluation of the specimen. If the specimenappears to require cleaning, the procedure should be agreedupon and it shou
23、ld be carried out with care. Any cleaning of alow-gloss or fragile surface may scratch or polish the surfaceand thus change the appearance of the specimen and render ituseless for measurement. A high-gloss specimen may usuallybe washed with clear water and blotted with untreated lenstissue or paper
24、towel. If the specimen is durable, a mildnonfluorescent, nonionic detergent that does not leave a filmcan be used with a soft cloth or bristle brush. If the specimenis durable and has an oily or stubborn contamination thatshould be removed, reagent grade isopropyl alcohol may beused. Follow all clea
25、ning techniques with a warm water rinseand drying by blotting, using untreated lint-free paper towel.NOTE 2Ceramic or porcelain-enameled instrument calibration stan-dards require periodic cleaning and the above procedures can generally beused safely.8. Handling Specimens8.1 Handle specimens by their
26、 edges. Do not allow objectsto contact the front surface of the specimen. When placing thespecimen on the instrument, avoid sliding it across the speci-men port.9. Report9.1 When the specimens submitted for appearance measure-ments depart from the ideal requirements, report the following:9.1.1 Their
27、 condition (Section 6),9.1.2 Method of cleaning (Section 7),9.1.3 Method of backing (5.3.1, 5.3.2, and 6.1), and9.1.4 Indicate direction of specimen submitted for measure-ment or averaging of data, or both, when required by direc-tionality (6.2).10. Keywords10.1 appearance; color; gloss; measurement
28、; opacity;uniformityASTM International takes no position respecting the validity of any patent rights asserted in 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
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31、 to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 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).D3964042
