1、Designation: D 6762 02a (Reapproved 2009)1Standard 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
2、, in the case of revision, 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.1NOTEUnits statement in 1.3 was added editorially in July 2009.1. Scope1.1 This test method
3、 provides for the quantitative visualdetermination of the film thickness required 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
4、.3 The values stated in inch-pound units are to be regardedas standard. The values given 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, assoc
5、iated 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:2D16 Terminology for Paint, Related Coatings, Materials,and
6、 ApplicationsD 609 Practice for Preparation of Cold-Rolled Steel Panelsfor Testing Paint, Varnish, Conversion Coatings, andRelated Coating ProductsD 1005 Test Method for Measurement of Dry-Film Thick-ness of Organic Coatings Using MicrometersD 1186 Test Methods for Nondestructive Measurement ofDry F
7、ilm Thickness of Nonmagnetic Coatings Applied toa Ferrous Base3D 1400 Test Method for Nondestructive Measurement ofDry Film Thickness of Nonconductive CoatingsApplied toa Nonferrous Metal Base3D 1729 Practice for Visual Appraisal of Colors and ColorDifferences of Diffusely-Illuminated Opaque Materia
8、lsD 1730 Practices for Preparation of Aluminum andAluminum-Alloy Surfaces for PaintingD 2805 Test Method for Hiding Power of Paints by Reflec-tometryE 691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 DefinitionsFor definitions of terms
9、used in this testmethod, refer to Terminology D16 and the Paint/CoatingsDictionary.44. 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 obtained,which
10、 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 the paint.5
11、. 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 doctor blade),
12、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 characteri
13、stics of the paint and is simpler inconcept and evaluation.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.26 on Optical Properties.Current edition approved July 1, 2009. P
14、ublished July 1, 2009. Originallyapproved in 2002. Last previous edition approved in 2002 as D 6762 - 02a.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 standa
15、rds Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.4Published by the Federation of Societies for Coatings Technology, 492Norristown Rd., Blue Bell, PA 19422.1Copyright ASTM International, 100 Barr Harbor Drive,
16、PO Box C700, West Conshohocken, PA 19428-2959, United States.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 render
17、the surface imper-vious to paint liquids.NOTE 2The red, gray, white and black areas should fall in thefollowing colorimetric range:CIE-Y % CAhARed 47 1018 2638Gray 2834White 8083Black 1 maxAValid for Illuminant D6510or C2, with 0/45 geometry.6.2 Illumination, a light source providing diffuse light o
18、freasonable 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 desired.6.4 Film Thickness Measuring Device, a film thicknessmeasuring device in accordance with Test Method
19、s 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, masking or adhesive.7. Preparation of Wedge-shaped Paint Film (HandSpray)7.1 Prepare the backer panel in
20、 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 viscosity.7.4 Attach spray gun to a suitable compressed air supplyline and adjust air pressure for consistent
21、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-shaped film. An example of a proce-dure for preparing a wedge-shaped film by means of handspray is show
22、n 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 Remove the panel and flash and bake per the recom-mended bake schedule.8. Preparation of Wedge-shaped Pai
23、nt 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 or adhesive tape.8.3 Reduce the material being tested to spray viscosity.8.4 Position the backer panel on
24、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-shaped film by means of anautomatic spray machine is shown in Appendix X2.NOTE 4The film thickness should
25、 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 recom-mended bake schedule.9. Evaluation Procedure9.1 Remove the panel from the oven and cool to roomtemperat
26、ure.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 test pattern is just barely or no longer visible. Thedry film thickness at this point is considered to be th
27、e 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. Report10.1 Report the coating under evaluation, with serial num-ber if applicable.10.2 Report the hiding
28、 power, as noted in 9.3, in m (mils).FIG. 1 Test PanelD 6762 02a (2009)1211. Precision and Bias511.1 Precision:11.1.1 An interlaboratory study of this test method wasconducted in which one operator in each of six laboratoriesmade two determinations each on six samples of paint. Thesamples represente
29、d 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 criteriashould be used for judging the acceptability of results at the95 % confidence
30、 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.11.1.1.2 ReproducibilityTwo results obtained by opera-tors in different laboratories should be considered suspect
31、 ifthey differ by more than the maximum allowable differencesshown in Table 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
32、 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 panelwith a uniform coat of the test material approximately 10 mthick.X1.2 Flash and then spray the lower34 of the pan
33、el with anadditional coat of the test material approximately 10 m thick.X1.3 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 experi
34、ence 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 from one endto the other should not exceed 50 m.X2. PREPARATION OF WEDGE-SHAPED PAINT FILM BY AUTOMATIC SPRAY MACHINE (EXAMPLE
35、)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 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
36、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, flooding or popping.5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR
37、: D01-1126.TABLE 1 Precision of Hiding Power of Paint by Visual Evaluationof Spray Applied 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
38、 (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 02a (2009)13ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of
39、 this standard are expressly advised that 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
40、 years andif not revised, either reapproved 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 co
41、mmittee, which you may attend. If you feel 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 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).D 6762 02a (2009)14
