1、Designation: D6762 18Standard Test Method forDetermining the Hiding Power of Paint by Visual Evaluationof Spray Applied Coatings1This standard is issued under the fixed designation D6762; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revis
2、ion, the year of 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 test method provides for the quantitative visualdetermination of the film thickness required to
3、achieve fullhiding. This film thickness is considered to be the hiding powerof a test paint.1.2 This method applies only to spray applied coatings butits concepts are valid for other methods of application as well.1.3 The values stated in inch-pound units are to be regardedas standard. The values gi
4、ven in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.4 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
5、 appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for
6、theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D16 Terminology for Paint, Related Coatings, Materials, andApplicationsD609 Practice for Preparation of
7、Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings, andRelated Coating ProductsD1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque Materia
8、lsD1730 Practices for Preparation of Aluminum andAluminum-Alloy Surfaces for PaintingD2805 Test Method for Hiding Power of Paints by Reflec-tometryD7091 Practice for Nondestructive Measurement of DryFilm Thickness of Nonmagnetic Coatings Applied toFerrous Metals and Nonmagnetic, Nonconductive Coat-i
9、ngs Applied to Non-Ferrous MetalsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsFor definitions of terms used in this testmethod, refer to Terminology D16 and the Paint/CoatingsDictionary.34. Summary of Test Method4.1 The
10、test paint is applied by means of spray applicationin a wedge-shaped film over a black and white, black and grayor red and gray pattern so that a thickness variation is obtained,which provides excess hiding at one end of the pattern andpartial hiding at the other end of the pattern.4.2 The dry film
11、is examined under standard illumination toselect the point where the pattern just becomes obscured. Thethickness of the film at this point is designated the hidingpower of the paint.5. Significance and Use5.1 This test method determines hiding power of a test paintby visual evaluation of a spray app
12、lied coating.NOTE 1Test Method D2805 describes an instrumental method fordetermining hiding power. The paint film is applied at a uniform thickness(for example with a doctor blade), the film thickness is measuredrigorously, and the opacity is determined photometrically. Hiding power isthereby determ
13、ined with a high degree of precision.5.2 Test Method D6762 is less precise than Test MethodD2805, but is commonly used since it is more closely related1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct respons
14、ibility ofSubcommittee D01.26 on Optical Properties.Current edition approved Sept. 1, 2018. Published September 2018. Originallyapproved in 2002. Last previous edition approved in 2017 as D6762 02a (2017).DOI: 10.1520/D6762-18.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orc
15、ontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Published by the Federation of Societies for Coatings Technology, 492Norristown Rd., Blue Bell, PA 19422.Copyright ASTM International
16、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides a
17、nd Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1to the application characteristics of the paint and is simpler inconcept and evaluation.6. Apparatus6.1 Test Surface, a smooth-surfaced paper chart, approxi-mately 2 by 11 in., with a test pattern
18、having adjacent black andwhite, black and gray or red and gray areas and coated with asuitable coating so as to render the surface impervious to paintliquids.NOTE 2The red, gray, white and black areas should fall in thefollowing colorimetric range:CIE-Y % CAhARed 47 1018 2638Gray 2834White 8083Black
19、 1 maxAValid for Illuminant D6510or C2, with 0/45 geometry.6.2 Illumination, a light source providing diffuse light ofreasonable intensity, preferably northern sky light or an ap-proximation of the same (see Practice D1729).6.3 Backer Panel, 4 by 12 in. steel or aluminum panel. Alarger panel may be
20、used if desired.6.4 Film Thickness Measuring Device, a film thicknessmeasuring device in accordance with Test Methods D1005 orD7091.6.5 Spray Equipment, either a hand spray gun or an auto-matic spray machine.6.6 Oven, capable of maintaining the bake schedule for theproduct being evaluated.6.7 Tape,
21、masking or adhesive.7. Preparation of Wedge-shaped Paint Film (HandSpray)7.1 Prepare the backer panel in accordance with PracticesD609 or D1730.7.2 Attach the desired test pattern to one side of the backerpanel with masking tape or adhesive tape.7.3 Reduce the material being tested to spray viscosit
22、y.7.4 Attach spray gun to a suitable compressed air supplyline and adjust air pressure for consistent fan spray.7.5 Position the backer panel so that the long side is vertical.The panel should be placed so that the spray gun tip isapproximately 12 in. from the face of the panel.7.6 Prepare a wedge-s
23、haped film. An example of a proce-dure for preparing a wedge-shaped film by means of handspray is shown in Appendix X1.NOTE 3The film thickness should vary from partial hiding at one endto excess hiding at the other end, but the total variation from one end tothe other should not exceed 2 mils (50 m
24、).7.7 Remove the panel and flash and bake per the recom-mended bake schedule.8. Preparation of Wedge-shaped Paint Film (AutomaticSpray Machine)8.1 Prepare the backer panel in accordance with PracticesD609 or D1730.8.2 Attach the desired test pattern to the one side of thebacker panel with masking ta
25、pe or adhesive tape.8.3 Reduce the material being tested to spray viscosity.8.4 Position the backer panel on the panel holder so that thelong side is horizontal or vertical depending on the type ofspray machine being used.8.5 Prepare a wedge-shaped film. An example of a proce-dure for preparing a we
26、dge-shaped film by means of anautomatic spray machine is shown in Appendix X2.NOTE 4The film thickness should vary from partial hiding at one endto excess hiding at the other end, but the total variation from one end tothe other should not exceed 2 mils (50 m).8.6 Remove the panel and flash and bake
27、 per the recom-mended bake schedule.9. Evaluation Procedure9.1 Remove the panel from the oven and cool to roomtemperature.9.2 Examine the test panel, as shown in Fig. 1, underillumination conditions as described in 6.2 at a viewing angleperpendicular to the surface of the panel, and select the point
28、where the test pattern is just barely or no longer visible. Thedry film thickness at this point is considered to be the hidingpower of the coating.NOTE 5The viewing angle may change depending on customerrequirements.9.3 Measure the film thickness at the point of hiding inaccordance with Test Methods
29、 D1005 or D7091.FIG. 1 Test PanelD6762 18210. Report10.1 Report the coating under evaluation, with serial num-ber if applicable.10.2 Report the hiding power, as noted in 9.3, in mils (m).11. Precision and Bias411.1 Precision:11.1.1 An interlaboratory study of this test method wasconducted in which o
30、ne operator in each of six laboratoriesmade two determinations each on six samples of paint. Thesamples represented two paint samples at each of threedifferent levels of hiding power. The samples were analyzedstatistically in accordance with Practice E691. On the basis ofthe standard deviations show
31、n in Table 1, the following criteriashould be used for judging the acceptability of results at the95 % confidence level:11.1.1.1 RepeatabilityTwo results obtained by the sameoperator should be considered suspect if they differ by morethan the maximum allowable differences shown in Table 1,Section A.
32、11.1.1.2 ReproducibilityTwo results obtained by operatorsin different laboratories should be considered suspect if theydiffer by more than the maximum allowable differences shownin Table 1, Section B.11.2 No information can be presented on the bias of theprocedure in Test Method D6762 for measuring
33、hiding powerbecause no acceptable reference standard is available.12. Keywords12.1 hiding power; spray applied coating; visual evaluationAPPENDIXES(Nonmandatory Information)X1. PREPARATION OF WEDGE-SHAPED PAINT FILM BY HAND SPRAY (EXAMPLE)X1.1 Mount the panel vertically and spray the entire panelwit
34、h a uniform coat of the test material approximately 0.4 mil(10 m) thick.X1.2 Flash and then spray the lower34 of the panel with anadditional coat of the test material approximately 0.4 mil (10m) thick.X1.3 Flash and then progressively spray the remaininglower areas of the panel, for example, bottom1
35、2, bottom14,etc., until complete hiding is achieved near the center of thepanel.NOTE X1.1Allow sufficient flash time, as experience dictates, toprevent sagging or flooding.NOTE X1.2The film thickness should vary from partial hiding at oneend to excess hiding at the other end, but the total variation
36、 from one endto the other should not exceed 2 mils (50 m).X2. PREPARATION OF WEDGE-SHAPED PAINT FILM BY AUTOMATIC SPRAY MACHINE (EXAMPLE)X2.1 Spray a wedge-shaped film using an automatic spraymachine. The spray machine should be programmed to yieldthe following spray pattern:Portion 1 Portion 2 Port
37、ion 3 Portion 41 Pass 2 Passes 3 Passes 4 PassesX2.2 After spraying Portion 4, rotate the panel 180 andrepeat as shown below:4 Passes 3 Passes 2 Passes 1 PassTotal Total Total Total8 Passes 6 Passes 4 Passes 2 PassesNOTE X2.1Allow sufficient flash time, as experience dictates, toprevent sagging, flo
38、oding or popping.4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:D01-1126. ContactASTM CustomerService at serviceastm.org.TABLE 1 Precision of Hiding Power of Paint by Visual Evaluationof Spray Applied CoatingsHiding LevelmilsAv
39、eragemilsStandard DeviationmilsMaximum Allowable DifferenceMils (micrometers)A. Repeatability (single operator)0.60.8 0.7 0.09 0.25 (6.3)1.01.4 1.2 0.11 0.30 (7.6)1.62.2 2.0 0.07 0.21 (5.3)B. Reproducibility (between laboratories)0.6.08 0.7 0.16 0.45 (11.3)1.01.4 1.2 0.39 1.08 (7.6)1.62.2 2.0 0.48 1
40、.33 (33.8)D6762 183ASTM 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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