ASTM D2486-17 Standard Test Methods for Scrub Resistance of Wall Paints.pdf

1、Designation: D2486 17Standard Test Methods forScrub Resistance of Wall Paints1This standard is issued under the fixed designation D2486; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parenth

2、eses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 These test methods cover a procedure for determiningthe resistance

3、 of wall paints to erosion caused by scrubbing,referred to herein after as “scrub resistance.”1.2 Two test methods are covered as follows:1.2.1 Test Method ACycles-to-failure obtained on testpaint.1.2.2 Test Method BRatio expressed as a percentage ofcycles-to-failure obtained on the test paint to th

4、at obtained ona concurrent run with a known reference paint.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is the

5、responsibility 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.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization establ

6、ished in the Decision on Principles for 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:2D3924 Specification for Environment for Conditioning andTesting

7、Paint, Varnish, Lacquer, and Related Materials(Withdrawn 2016)3D4213 Test Method for Scrub Resistance of Paints byAbrasion Weight Loss3. Summary of Test Method3.1 In Test Method A, the test paint is applied to a blackplastic panel. After curing, the coated panel is placed over a12.7 wide by 0.25-mm

8、thick (12-in. by 10-mil) shim and heldin place on a drawdown plate in a washability machine bymeans of a gasketed frame. The coated panel is then scrubbedwith a bristle brush and an abrasive scrub medium until thepaint film is removed in one continuous thin line across theshim.3.2 In Test Method B,

9、the test paint and a reference paint areapplied simultaneously perpendicular to the length of the blackplastic panel. After curing, the coated panel is placed over two12.7 by 0.25-mm (12-in. by 10-ml) shims that are positionedunder each coating. The coatings are then scrubbed with abristle brush and

10、 an abrasive scrub medium until each paintfilm is removed in one continuous thin line across its ownshim.4. Significance and Use4.1 Paints often become soiled, especially near doorways,windows, and in work and play areas. These test methods coverthe determination of the relative resistance of differ

11、ent paints toerosion when repeatedly scrubbed during the life of the paint.4.2 Test Method D4213 is a similar scrub resistance testusing a weight-loss technique and reporting volumetric filmerosion rates.4.3 Test Method A measures scrub resistance by the tradi-tional cycles-to-failure concept. Poor

12、correlation in scrubtesting can be attributable to among other things variations inthe stiffness of the brush bristles, condition of washabilitytester, application and drying conditions. In an attempt toimprove reproducibility, Test Method B has been developed.5. Apparatus5.1 Straight Line Washabili

13、ty Machine.5.1.1 Accessory Apparatus: (see Figs. 1 and 2).5.1.1.1 Nylon Bristle Brush and Accessories, (total weight454 6 10 g).1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings, Materials, and Applications and are the directresponsibility of Subcommit

14、tee D01.42 on Architectural Coatings.Current edition approved June 1, 2017. Published July 2017. Originally approvedin 1966. Last previous edition approved in 2016 as D2486 06 (2016). DOI:10.1520/D2486-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer S

15、ervice at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West C

16、onshohocken, 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 and Recommendations issued by the World Trade

17、 Organization Technical Barriers to Trade (TBT) Committee.15.1.1.2 Drawdown Plate, 454 by 165 by 6.3 mm (1778 by612 by14 in.).5.1.1.3 Brass Shims, 12.7- by 0.25-mm (12-in. by 10-mils).Its length can be fitted to the width of the drawdown plate.5.2 Film Applicator, having 0.18-mm (7-mil) clearance an

18、d6.25-mm (14-in.) edge and width of 135 mm (514-in.).6. Reagents and Materials6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.6.2 Black Plastic Panels.4,56.3 Abrasive Scrub Medium.5,66.3.1 Laboratory standardized abrasive scrub medium con-sisting of the following:gramsWater,

19、distilled or deionized 49.4AHydroxyethyl cellulose5,70.8Ammonium hydroxide, 28 % 0.1Detergent5,82.0Trisodium phosphate, anhydrous 2.0Silica5,945.0Acetic acid (glacial) 0.7BPreservative5,100.03gAAdjust to achieve viscosity of 110 to 120 Krebs units before use.BVary to achieve a pH of 9.5 to 10.6.4 Re

20、ference paint when using Test Method B.7. Preparation of Apparatus7.1 Washability MachineThe straight line washability ma-chine should be leveled before use and operated at 37 6 1cycles per minute.4Dull black plastic panels, P-121-10N, 165 by 432 by 0.25 mm (612 by 17 in.by 10 mils) manufactured by

21、The Leneta Co., 15 Whitney Rd., Mahwah, NJ 07430were used in the original development of this standard in order to get the results inthese test methods.5If you are aware of alternative suppliers, please provide this information toASTM International Headquarters. Your comments will receive careful co

22、nsider-ation at a meeting of the responsible technical committee,1which you may attend.6The sole source of supply of the abrasive scrub medium known to thecommittee at this time is The Leneta Company.7Cellosize QP-4400H, The Dow Chemical Company, Midland, Michigan, wasused in developing the Precisio

23、n and Bias statement. Other equivalent molecularweight cellulosic thickeners can be used such as Natrosol 250 MR, AshlandAqualon, Wilmington, Delaware.8The sole source of supply of the Triton X-100 detergent known to thecommittee at this time is The Dow Chemical Company, Midland, Michigan.9The follo

24、wing silica is recommended by this Subcommittee and is used incommercially available abrasive scrub media. It is also known to be used bycompanies who blend their own abrasive scrub media: Imsil 1240, manufactured byUnimin Specialty Minerals Inc., 258 Elm St., New Canaan, CT 06840.10The preservative

25、 package recommended is BIT, 1,2Benzisothiazol-3(2H)-one. There are several suppliers who offer BIT-based agents.FIG. 1 Accessory Apparatus for Scrub TestFIG. 2 Accessory Apparatus for Scrub TestD2486 1727.2 BrushReplace the brush when the bristles have be-come worn to a point that the bristles exte

26、nd less than 15 mm(58 in.) from the block. Mark the ends of the brush to ensure itis oriented in the same direction for each use.7.2.1 Brushes (that are in frequent use)Brushes that are infrequent use shall be stored in water. Each time before startingthe first test of the day, remove the brush and

27、rinse in water,then precondition the brush, by running it for 400 cycles on ascrub panel, after which it is ready for test work.7.2.2 Brushes (that are not in regular use)Brushes thatwill not be used on a regular basis shall be washed outthoroughly in water after their last use and stored with thebr

28、istling side up under ambient conditions. Before being usedagain, the brush should be soaked in water for at least 24 h.Precondition the brush as directed in 7.2.1 before starting thetest work.7.3 Brush HolderFor washability testers that include aseparate brush holder, insert a 3.2-mm (18-in.) thick

29、 rubber matin the holder above the brush block. When in operation, thismat allows the brush to ride evenly on the paint surface withouttilting. The brush must fit loosely in the holder. Mount thebrush in the holder being sure that the mat is in place above thebrush block and that the brush and holde

30、r are always in thesame position.TEST METHOD A8. Procedure8.1 Stir the test paint thoroughly and strain to remove allskins and particles. Make three drawdowns of each paint. Drawdown the paint on the black plastic panel using the sameoperator and same 0.18-mm (7.0-mil) clearance film applicator.The

31、time for application should be fairly slow 3 to 4 s fromend to end to prevent formation of pinholes or holidays in thefilm. Air dry in a horizontal position for 7 days in anconditioning chamber at 23 6 2C (73.5 6 3.5F) and 50 65 % relative humidity in accordance with Specification D3924.8.2 Soak the

32、 brush in water overnight. Clean the plate andset it in the pan of the washability tester. Ensure that the shimis smooth and free of burrs and placed perpendicular to the pathof the brush. Wipe the test panel carefully and place it on topof the shimmed plate with the painted side up. Be sure thatthe

33、re are no defects in the film above the shim and that the testarea is level. Place the frame over the drawdown being surethat the entire gasket is on the painted surface. Clamp thegasket in place. The clamps should be tight enough to ensureclose contact, but not tight enough to cause warping of thep

34、anel.8.3 Before beginning the test, it should be confirmed that thebrush has been preconditioned for 400 cycles as outlined in7.2.1. Remove the brush and shake vigorously to remove anyexcess water. Stir the abrasive scrub medium and spread 10 guniformly over the brush bristles. Place the brush at on

35、e end ofthe path. Wet the panel with 5 mL of water in the path of thebrush.8.4 Start the test. After each 400 cycles before failure,remove the brush (do not rinse), add 10 g of stirred abrasivescrub medium and place 5 mL of water on the path of the brushbefore continuing.8.5 Record the number of cyc

36、les to remove one continuousthin line of paint film across the 12.7-mm (12-in.) width of theshim. Stop the machine and wipe off the shim area todetermine, if necessary, if the end point is achieved.8.6 Test two of the drawdowns. If the two results differ bymore than 30 % of the average, test the thi

37、rd drawdown. If oneof the three results is obviously discrepant, discard it, thenaverage the results from the remaining drawdowns.TEST METHOD B9. Procedure9.1 Stir the test paint and reference paint thoroughly andstrain to remove all skins and particles. Draw down the test andreference paints side b

38、y side perpendicular to the length of thepanel following procedures outlined in 8.1. Prepare threedrawdowns for each test/reference paint. The paints should bedrawn down simultaneously and the painted portion should bein the middle of the chart. Air dry in a horizontal position for7 days at standard

39、 conditions.9.2 Soak the brush in water overnight. Clean the plate andset it in the pan of the washability machine. Centrally place twoshims, one each under the test paint and one under thereference paint drawdown areas on the chart. Wipe the testpanel carefully and place it on top of the shimmed pl

40、ate withthe painted side up. Be sure that there are no defects in the filmabove the shims and that the test areas are level. Place thegasket over the painted surface and clamp in place.9.3 Remove the brush and shake it vigorously to removeany excess water. Before testing, the brush shall be conditio

41、nedfor 400 cycles as outlined in 7.2.1. Follow procedures outlinedin 8.3 and 8.4. It is recommended that the first two panels to betested are prepared by altering the position of the referencepaint, that is, one panel has the reference paint on the right, andthe second panel has the reference paint

42、on the left.9.4 Record respectively the number of cycles to remove onecontinuous thin line of paint film from both the test andreference paints across the 12.7-mm (12-in.) width of each ofthe shims. Stop the machine and wipe off the shim areas todetermine, if necessary, if each end point is achieved

43、9.5 Test two of the drawdowns. If the two results differ bymore than 30 %, test the third drawdown. If one of the threeresults is obviously discrepant, discard it, then average theresults from the remaining drawdowns.10. Report10.1 Report the following information:10.1.1 When using Test Method A, r

44、eport the mean numberof cycles to failure.10.1.2 When using Test Method B, report a percentage asfollows:D2486 173Cycles for test paintCycles for reference paint3100 (1)if:Result is 100 %, test paint has better scrub resistance thanreference paint.if:Result is 100 %, test paint has poorer scrub resi

45、stance thanreference paint.10.1.3 Method used (Test Method A or Test Method B).10.1.4 Referenced paint used, if using Test Method B.10.1.5 Outline any deviations from standard procedures.11. Precision and Bias11.1 PrecisionIn an interlaboratory study of these testmethods, scrub resistance was record

46、ed in five laboratoriesusing three coatings. The following criteria should be used forjudging the acceptability of results of scrub resistance tests ata 95 % confidence level.Test Method A11.1.1 RepeatabilityDuplicate results by a single operatorshould be considered suspect if they differ by more th

47、an 30 %of their mean value.11.1.2 ReproducibilityTwo results (each the mean of du-plicate measurements) obtained by operators in different labo-ratories should be considered suspect if they differ by morethan 58 % of their mean.Test Method B11.1.3 On the basis of an interlaboratory study in whichope

48、rators in five laboratories tested five coatings, includingboth flat and semi-gloss coatings, the following criteria shouldbe used for judging the acceptability of the results at the 95 %confidence level:11.1.3.1 RepeatabilityTwo results (each the mean of du-plicate measurements) obtained by the sam

49、e operator should beconsidered suspect if they differ by more than 25 % of theirmean value.11.1.3.2 ReproducibilityTwo results (each the mean ofduplicate measurements) obtained by operators in differentlaboratories should be considered suspect if they differ by morethan 58 % of their mean.11.2 BiasBias is not applicable to these test methods.12. Keywords12.1 scrub resistance; wet abrasion resistanceASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of