1、Designation: D 1212 91 (Reapproved 2007)Standard Test Methods forMeasurement of Wet Film Thickness of Organic Coatings1This standard is issued under the fixed designation D 1212; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、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 These test methods cover the determination of wet filmthickness of organic coatings such as paint, varnish, a
3、ndlacquer. 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 to 700 m on the metric scale series (Sections 5-8).1.1.2 In Test Method B
4、, 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 This standard does not purport to address all of thesafety concerns, if any
5、, 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 Documents2.1 ASTM Standards:2D 823 Practices for Producing Films of Uniform Thic
6、knessof 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 determined as quickly as possible to reduceshrinkage due to solvent loss
7、.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 surface ispushed into the wet film until the center touches the substr
8、ate.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 measurements aid in the predictionof dry film thickness. In instances where dry f
9、ilm 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.TEST METHOD A5. Apparatus5.1 Wet Film Thickness GageTwo versions of the ga
10、ge 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 symmetrical.As the gageis rolled on the film, there is a change in clear
11、ance 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 concentric wheels, as shown in Fig. 1,to the outside of the gage and closer to
12、 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 the eccentric wheel closer to one of thesupporting concentric wheels.5.3
13、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.Therefore, the range of the particular gage selected for useshould be such that the measured film thickness falls within,and pref
14、erably toward the center of the middle 80 % of eachscale. Gages are available covering the following ranges inmils and microns:1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommitt
15、ee 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 D 1212 - 91 (2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Se
16、rvice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Both versions 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.
17、 Interested parties are invited to submit information regarding theidentification of acceptable alternatives to this patented item to the Committee onStandards, ASTM Headquarters. Your comments will receive careful considerationat a meeting of the responsible technical committee, which you may atten
18、d.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Range, milsSmallestGraduation, mils0to2 0.10to4 0.22to12 0.510 to 30 1.020 to 60 2.0Range, mSmallestGraduation, m0to40 2.00 to 100 5.0050 to 250 10.00200 to 700 25.006. Procedure6.1 A
19、pply the material in accordance with Practices D 823to suitable plane rigid panels of area sufficiently large to permitfilm thickness measurements at least 25 mm (1 in.) from anyedge. Determine the film thickness immediately after applica-tion.6.2 Support the test panels on a suitable level base in
20、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 between the eccentric wheel and the film isdirectly over the wet film. Roll the gage over the film
21、 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 determine the mean which is considered as onereading.6.3 If the coating contains a solvent that evapora
22、tes 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 readings and the rangeand smallest graduation of the gage used.8. Precision48.1 In an interlaborato
23、ry study of this test method, in whichtwo operators in at least six laboratories made measurementswith 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 and the4Supporting data ha
24、ve been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D01-1023.FIG. 1 Interchemical Wet Film Thickness GagesFIG. 2 Model “C” Wet Film Thickness GagesD 1212 91 (2007)2between-laboratories standard deviation 0.18 for two determi-nations and 0.17 for four
25、 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 mean of oppositerolls of the 0- to 2- or 0- to 4-mil gage, obtained by the sameoperator should
26、 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 operators in differentlaboratories, should be considered suspect if they differ bymore than 0
27、.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 having a radius of curvatureof 250 mm mounted in a short tube T1, that slides freely in anoute
28、r 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 an oversized circular spot of diameterD, on the convex lens (larger than the diameter D corres
29、pond-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. Procedure10.1 Apply the material to suitable plane, rigid panels ofarea sufficiently large to p
30、ermit 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 there will be no movement or spring of thepanels during the film thickness measurements. As sh
31、own 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 through the notches in the outer tube but preventinglateral motion of the gage. Upon releasing the
32、 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: and KE = CG = thickness of overlying displacedcoating.10.3 Remove the gage from the surface, me
33、asure 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 as one reading. Make at least two separate tests toobtain the grand mean film thickness.10.4 Al
34、though 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 an extent that would affect themeasurements.10.5 If coarse particles in the wet film prevent t
35、he lens frommaking contact with the base at the point F, the results will notbe valid.11. 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
36、 printed table supplied with the Pfundgage. 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
37、convex lens (250 mm).5Keinrath, G., “Sphere Penetration Gage,” National Institute of Standards andTechnology Circular, NIST, Nat No. 585, Section 1.06, p. 4.FIG. 3 Pfund GageD 1212 91 (2007)3based on the fundamental assumption that t is exactly onehalf of the total thickness of the film at the diame
38、ter 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 thickness of material,based on freshly prepared films of known wet film thickness, asmeasured
39、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. Precision13.1 In an interlaboratory study of this method, in whichtwo operators in five laboratories made measurements on threematerials applied at
40、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 mil for fourmeasurements. Based on these standard deviations, the follow-ing criteria should be
41、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 considered suspect if they differ by morethan 0.6 mil for two determinations and 0.8 mil for fourde
42、terminations.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.14. Keywords14.1 eccentric center wheel; glass panel reading surface;metals and metallic mater
43、ials; 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 mentionedin this standard. Users of this standard are expressly advised that determination of the va
44、lidity 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 reapproved or withdrawn. Your co
45、mments 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 feel that your comments hav
46、e 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 1212 91 (2007)4
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