1、Designation: D1212 91 (Reapproved 2007)1Standard Test Methods forMeasurement of Wet Film Thickness of Organic Coatings1This standard is issued under the fixed designation D1212; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the y
2、ear 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.1NOTEResearch report was added editorially to Test Method B in April 2012.1. Scope1.1 These test methods cover the determin
3、ation of wet filmthickness of organic coatings such as paint, varnish, andlacquer. Two methods are described as follows:1.1.1 In Test Method A, the Wet Film Thickness Gage(English or Metric graduation (see 5.1) is used to measure wetfilm thicknesses up to 60 mils on the English scale series, andup t
4、o 700 m on the metric scale series (Sections 5-8).1.1.2 In Test Method B, the Pfund Gage is used to measurewet film thicknesses up to 14.2 mils (360 m) (Sections 9-13).1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 Thi
5、s 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 Document
6、s2.1 ASTM Standards:2D823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test Panels3. Summary of Test Methods3.1 The material is applied in the laboratory to plane, rigidtest panels or in the field to the surface being coated. The wetfilm thickness is d
7、etermined as quickly as possible to reduceshrinkage due to solvent loss.3.2 In Test Method A, a gage with one eccentric and twoconcentric wheels is rolled over the surface and the point wherethe eccentric wheel first touches the wet film is determined.3.3 In Test Method B, a gage with a convex lower
8、 surface ispushed into the wet film until the center touches the substrate.The diameter of the spot of wet coating left on the convexsurface is measured and the film thickness calculated from thediameter of the spot and the radius of curvature.4. Significance and Use4.1 Wet film thickness measuremen
9、ts aid in the predictionof dry film thickness. In instances where dry film thicknesscannot be measured nondestructively, wet film thickness isfrequently specified. Also, the ability to determine wet filmthickness during application can provide the opportunity tocorrect the application procedures.TES
10、T METHOD A5. Apparatus5.1 Wet Film Thickness GageTwo versions of the gage arenow in use:3The original design as shown in Fig. 1 and a laterdesign as shown in Fig. 2. Both designs consists of an eccentriccenter wheel supported by two concentric wheels so as toprovide two scales that are bilaterally s
11、ymmetrical.As the gageis rolled on the film, there is a change in clearance between thewet film and the eccentric wheel. The point at which the filmfirst touches the center wheel measures the thickness of thefilm.5.2 The later design shown in Fig. 2, moves the eccentricwheel from between the concent
12、ric wheels, as shown in Fig. 1,to the outside of the gage and closer to one of the concentricwheels. Gage reading errors of parallax across the gage areeliminated as the two scales are placed directly on the eccentricwheel and errors when measuring on uneven support surfacesare reduced by placing th
13、e eccentric wheel closer to one of thesupporting concentric wheels.5.3 Best precision is obtained when using the near linearcentral portion of each scale, constituting about 80 % of itstotal range as shown in the diagram in Fig. 1 and Fig. 2.1These test methods are under the jurisdiction of ASTM Com
14、mittee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommittee D01.23 on Physical Properties of Applied PaintFilms.Current edition approved June 1, 2007. Published June 2007. Originallyapproved in 1952. Last previous edition approved in 2001 as
15、D1212 - 91 (2001).DOI: 10.1520/D1212-91R07E01.2For 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.3Both versions
16、of this gage (Interchemical (INMONT) and Model “C”) arecovered by U.S. Patents 2 507 592 and 3 128 558 and are issued to Maynard R.Euverard. Interested parties are invited to submit information regarding theidentification of acceptable alternatives to this patented item to the Committee onStandards,
17、 ASTM Headquarters. Your comments will receive careful considerationat a meeting of the responsible technical committee, which you may attend.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Therefore, the range of the particular gage
18、 selected for useshould be such that the measured film thickness falls within,and preferably toward the center of the middle 80 % of eachscale. Gages are available covering the following ranges inmils and microns:Range, milsSmallestGraduation, mils0to2 0.10to4 0.22to12 0.510 to 30 1.020 to 60 2.0Ran
19、ge, mSmallestGraduation, m0to40 2.00 to 100 5.0050 to 250 10.00200 to 700 25.006. Procedure6.1 Apply the material in accordance with Practices D823 tosuitable plane rigid panels of area sufficiently large to permitfilm thickness measurements at least 25 mm (1 in.) from anyedge. Determine the film th
20、ickness immediately after applica-tion.6.2 Support the test panels on a suitable level base in sucha way that there will be no movement or spring of the panelsduring the film thickness measurements. Place the gage on thewet film so that the minimum marking is at the top and thegreatest clearance bet
21、ween the eccentric wheel and the film isdirectly over the wet film. Roll the gage over the film one-halfrevolution in one direction toward the minimum marking onthe gage and repeat in the opposite direction. Read the pointsat which the coating first makes contact with the eccentricwheel and determin
22、e the mean which is considered as onereading.6.3 If the coating contains a solvent that evaporates rapidlyor if the solids content is low, make at least a second separatereading on a freshly applied film and calculate the mean of theseparate readings.7. Report7.1 Report the mean of the separate read
23、ings and the rangeand smallest graduation of the gage used.8. Precision48.1 In an interlaboratory study of this test method, in whichtwo operators in at least six laboratories made measurements4Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Resear
24、ch Report RR:D01-1023.FIG. 1 Interchemical Wet Film Thickness GagesFIG. 2 Model “C” Wet Film Thickness GagesD1212 91 (2007)12with the 0- to 2- and 0- to 4-mil gages on three materials,applied at two film thicknesses, the pooled within-laboratorystandard deviation was found to be 0.12 mils with 34 df
25、 and thebetween-laboratories standard deviation 0.18 for two determi-nations and 0.17 for four determinations with 25 df. Based onthese standard deviations, the following criteria should be usedfor judging the acceptability of results at the 95 % confidencelevel:8.1.1 RepeatabilityResults, each the
26、mean of oppositerolls of the 0- to 2- or 0- to 4-mil gage, obtained by the sameoperator should be considered suspect if they differ by morethan 0.4 mil for two determinations and 0.5 mil for fourdeterminations.8.1.2 ReproducibilityTwo results, each the mean of twoseparate determinations, obtained by
27、 operators in differentlaboratories, should be considered suspect if they differ bymore than 0.55 mil.8.2 The precision of higher range gages is expected to beproportional to film thickness.TEST METHOD B9. Apparatus9.1 Pfund GageThe gage5shown in Fig. 3 consists of aconvex lens L with lower surface
28、having a radius of curvatureof 250 mm mounted in a short tube T1, that slides freely in anouter tube T2. The compression springs S keep the convexsurface out of contact with the wet film until pressure is appliedto the top of T1, forcing the lens L down through the film. Thedisplaced material forms
29、an oversized circular spot of diameterD, on the convex lens (larger than the diameter D correspond-ing to the thickness T of the film) because of the meniscuseffect due to wetting and surface tension effects on the glasslens.9.2 Steel Scale (furnished with Pfund Gage), calibrated inmillimetres.10. P
30、rocedure10.1 Apply the material to suitable plane, rigid panels ofarea sufficiently large to permit film thickness measurements atleast 25 mm (1 in.) from any edge. Determine the filmthickness immediately after application.10.2 Support the test panels on a suitable flat level base insuch a way that
31、there will be no movement or spring of thepanels during the film thickness measurements. As shown inthe second diagram in Fig. 3, place the gage on the coatedsurface and slowly force the inner tube down as far as it will go(point F on surface AB of the base) allowing displaced materialto escape thro
32、ugh the notches in the outer tube but preventinglateral motion of the gage. Upon releasing the pressure, anoversized circular spot is retained on the lens. Its diameter D isthe length of the line EG and corresponds to the sum of twothicknesses: AK = BC = thickness of underlying undisturbedcoating: a
33、nd KE = CG = thickness of overlying displacedcoating.10.3 Remove the gage from the surface, measure to thenearest 0.5 mm in two directions at approximate right anglesthe diameter of the oversize spot on the lens using the steelscale, and determine the mean of the two measurements that isconsidered a
34、s one reading. Make at least two separate tests toobtain the grand mean film thickness.10.4 Although this procedure refers to measurements on flattest panels, the same technique may be used in the field or shopon commercial articles, provided the substrate is not distortedat the point of contact to
35、an extent that would affect themeasurements.10.5 If coarse particles in the wet film prevent the lens frommaking contact with the base at the point F, the results will notbe valid.5Keinrath, G., “Sphere Penetration Gage,” National Institute of Standards andTechnology Circular, NIST, Nat No. 585, Sec
36、tion 1.06, p. 4.FIG. 3 Pfund GageD1212 91 (2007)1311. Calculation11.1 The relations between the diameter of the oversizedspot on the lens in millimetres, the approximate thickness ofthe undisturbed wet film, and the coverage in square feet pergallon are given in a printed table supplied with the Pfu
37、ndgage. It has been found that empirical equations give approxi-mate values for the wet film thickness, t, as follows:t in mils!5D23 1000!/16R 3 25.4 5 0.0943 D2t in micrometres!5D23 1000!/16R 5 0.25 D2where:D = diameter of spot, mm, andR = radius of curvature of convex lens (250 mm).based on the fu
38、ndamental assumption that t is exactly onehalf of the total thickness of the film at the diameter D,asshown in the second diagram in Fig. 3.11.2 The Pfund gage cannot be calibrated by the manufac-turer prior to delivery. For the best results, a correction factormust be established for each type and
39、thickness of material,based on freshly prepared films of known wet film thickness, asmeasured by Test Method A (Interchemical Wet Film Thick-ness Gage).12. Report12.1 Report the mean of at least two separate readings as thewet film thickness.13. Precision413.1 In an interlaboratory study of this met
40、hod, in whichtwo operators in five laboratories made measurements on threematerials applied at two film thicknesses, the pooled within-laboratory standard deviation was found to be 0.21 mil with 30df and the between-laboratories standard deviation with 24 df0.285 mil for two measurements and 0.265 m
41、il for fourmeasurements. Based on these standard deviations, the follow-ing criteria should be used for judging the acceptability ofresults at the 95 % confidence level:13.1.1 RepeatabilityResults, which are the mean of thetwo measurements at right angles, obtained by the sameoperator should be cons
42、idered suspect if they differ by morethan 0.6 mil for two determinations and 0.8 mil for fourdeterminations.13.1.2 ReproducibilityTwo results, each the mean of twoseparate determinations, obtained by operators in differentlaboratories, should be considered suspect if they differ bymore than 0.85 mil
43、.14. Keywords14.1 eccentric center wheel; glass panel reading surface;metals and metallic materials; paint coated panels; wet filmthickness gage; wet film thickness measurementASTM International takes no position respecting the validity of any patent rights asserted in connection with any item menti
44、onedin this standard. Users of 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 a
45、nd must be reviewed every five 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
46、of theresponsible technical committee, 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 Bo
47、x 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D1212 91 (2007)14
