1、Designation: D 6762 02aStandard Test Method forDetermining the Hiding Power of Paint by Visual Evaluationof Spray Applied Coatings1This standard is issued under the fixed designation D 6762; the number immediately following the designation indicates the year oforiginal adoption or, in the case of re
2、vision, the year of last revision. 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 test method provides for the quantitative visualdetermination of the film thickness required
3、 to 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 This standard does not purport to address all of thesafety concerns, if any, a
4、ssociated 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 Documents2.1 ASTM Standards:D16 Terminology for Paint, Related Coatings, Materials,
5、and Applications2D 609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings, andRelated Coating Products2D 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using Micrometers2D 1186 Test Methods for Nondestructive Measurement o
6、fDry Film Thickness of Nonmagnetic Coatings Applied toa Ferrous Base2D 1400 Test Method for Nondestructive Measurement ofDry Film Thickness of Nonconductive CoatingsApplied toa Nonferrous Metal Base2D 1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque M
7、aterials2D 1730 Practices for Preparation of Aluminum andAluminum-Alloy Surfaces for Painting3D 2805 Test Method for Hiding Power of Paints by Reflec-tometry2E 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method43. Terminology3.1 DefinitionsFor definitions
8、 of terms used in this testmethod, refer to Terminology D16 and the Paint/CoatingsDictionary.54. Summary of Test Method4.1 The 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 obta
9、ined,which provides excess hiding at one end of the pattern andpartial hiding at the other end of the pattern.4.2 The dry film 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 t
10、he paint.5. Significance and Use5.1 This test method determines hiding power of a test paintby visual evaluation of a spray applied coating.NOTE 1Test Method D 2805 describes an instrumental method fordetermining hiding power. The paint film is applied at a uniform thickness(for example with a docto
11、r blade), the film thickness is measuredrigorously, and the opacity is determined photometrically. Hiding power isthereby determined with a high degree of precision.5.2 Test Method D 6762 is less precise than Test MethodD 2805, but is commonly used since it is more closely relatedto the application
12、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 having adjacent black andwhite, black and gray or red and gray areas and coated with asuitable varnish or lacquer so as to
13、 render the surface imper-vious to paint liquids.NOTE 2The red, gray, white and black areas should fall in thefollowing colorimetric range:1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSu
14、bcommittee D01.26 on Optical Properties.Current edition approved Dec. 10, 2002. Published February 2003. Originallyapproved in 2002. Last previous edition approved in 2002 as D 6762 - 02e1.2Annual Book of ASTM Standards, Vol 06.01.3Annual Book of ASTM Standards, Vol 02.05.4Annual Book of ASTM Standa
15、rds, Vol 14.02.5Published by the Federation of Societies for Coatings Technology, 492Norristown Rd., Blue Bell, PA 19422.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.CIE-Y % CAhARed 47 1018 2638Gray 2834White 8083Black 1 maxAValid
16、 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 D 1729).6.3 Backer Panel, 4 by 12 in. steel or aluminum panel. Alarger panel may be used if des
17、ired.6.4 Film Thickness Measuring Device, a film thicknessmeasuring device in accordance with Test Methods D 1005,D 1186, and D 1400.6.5 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,
18、 masking or adhesive.7. Preparation of Wedge-shaped Paint Film (HandSpray)7.1 Prepare the backer panel in accordance with PracticesD 609 or D 1730.7.2 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 visco
19、sity.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 wedg
20、e-shaped 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 50 m.7.7
21、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 PracticesD 609 or D 1730.8.2 Attach the desired test pattern to the one side of thebacker panel with masking tape o
22、r 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 wedge-
23、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 50 m.8.6 Remove the panel and flash and bake per the reco
24、m-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 pointwhere the tes
25、t 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 per TestMethods D 1005, D 1186,orD 1400.10.
26、 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 m (mils).11. Precision and Bias611.1 Precision:11.1.1 An interlaboratory study of this test method wasconducted in which one operator in each of six laboratoriesmade t
27、wo 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 E 691. On the basis ofthe standard deviations shown in Table 1, the following criteria6Support
28、ing data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D011126.FIG. 1 Test PanelD 6762 02a2should be used for judging the acceptability of results at the95 % confidence level:11.1.1.1 RepeatabilityTwo results obtained by the sameoperator shou
29、ld be considered suspect if they differ by morethan the maximum allowable differences shown in Table 1,Section A.11.1.1.2 ReproducibilityTwo results obtained by opera-tors in different laboratories should be considered suspect ifthey differ by more than the maximum allowable differencesshown in Tabl
30、e 1, Section B.11.2 No information can be presented on the bias of theprocedure in Test Method D 6762 for measuring hiding powerbecause no acceptable reference standard is available.12. Keywords12.1 hiding power; spray applied coating; visual evaluationAPPENDIXES(Nonmandatory Information)X1. PREPARA
31、TION OF WEDGE-SHAPED PAINT FILM BY HAND SPRAY (EXAMPLE)X1.1 Mount the panel vertically and spray the entire panelwith a uniform coat of the test material approximately 10 mthick.X1.2 Flash and then spray the lower34 of the panel with anadditional coat of the test material approximately 10 m thick.X1
32、.3 Flash and then progressively spray the remaininglower areas of the panel, for example, bottom12 , 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 s
33、hould vary from partial hiding at oneend to excess hiding at the other end, but the total variation from one endto the other should not exceed 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
34、 machine should be programmed to yieldthe following spray pattern:Portion 1 Portion 2 Portion 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
35、PassesNOTE X2.1Allow sufficient flash time, as experience dictates, toprevent sagging, flooding or popping.ASTM 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 th
36、at determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reappr
37、oved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you f
38、eel that your comments have not received a fair hearing you shouldmake your views known 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 re
39、prints (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).TABLE 1 Precision of Hiding Power of Paint by Visual Evaluationof Spray Ap
40、plied CoatingsHiding LevelmilsAveragemilsStandard 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 1.33 (33.8)D 6762 02a3
