1、Designation:D269805(Reapproved 2015)Standard Test Method forDetermination of the Pigment Content of Solvent-ReduciblePaints by High-Speed Centrifuging1This standard is issued under the fixed designation D2698;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.This standard has been approved for use by agencies of the U.S.Department of Defense.1.Scope1.1 Th
3、is test method covers the separation of pigment fromsolvent-reducible paints and the calculation of the percentpigment from the results of nonvolatile determinations on thetotal paint and the separated vehicle.NOTE1This test method has been proven to be applicable to mostsolvent-reducible paints,the
4、 exception being those paints containingseverely bleeding pigments or pigments such as carbon black that are verydifficult or impossible to centrifuge.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not
5、 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 Documents2.1 ASTM Standards:2D2
6、369 Test Method for Volatile Content of Coatings3.Significance and Use3.1 This test method describes a rapid method for separatingpigment from solvent-reducible paints.3.2 This test method is used by paint producers and con-sumers for product acceptance and process control.4.Apparatus4.1 Laboratory
7、Centrifuge,capable of developing 32 000 gor higher.35.Procedure5.1 Shake the sample for 10 min on a mechanical shaker,stir with a paddle to loosen any caked pigment,and shake againfor 10 min.If necessary,repeat until there are no lumps presentand the sample is thoroughly mixed.5.2 Add the mixed pain
8、t to the centrifuge container untilsufficient paint is added to permit the recovery of 25 mLminimum of clear vehicle.Revolve the bowl at 32 000 g orhigher for 15 min or until a clear vehicle is obtained.5.3 Transfer the vehicle carefully,so as not to dislodge anyof the pigment from the walls,into a
9、jar that is immediatelycapped to prevent any solvent losses by evaporation.Use thisvehicle for the determination of the nonvolatile content of theseparated vehicle.6.Percent Paint and Vehicle Solids6.1 Determine the percent nonvolatile content of the origi-nal paint and the separated vehicle in acco
10、rdance with TestMethod D2369.7.Calculation7.1 Calculate the weight percent pigment of paint,P,asfollows:P 5A 2 B!3100/1002 B(1)where:A=nonvolatile content of paint,%,andB=nonvolatile content of separated vehicle,%.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related
11、Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved June 1,2015.Published June 2015.Originallyapproved in 1965.Last previous edition approved in 2010 as D2698 05(2010).DOI:10.1520/D2698
12、-05R15.2For 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.3A supercentrifuge or a centrifuge equipped with a high-spe
13、ed head have beenfound satisfactory for this purpose.Any centrifuge capable of developing 32 000 gand having facilities for sealing the specimen to prevent solvent loss should alsoprove to be satisfactory.To calculate the gravities developed by a particular centrifuge use the followingcalculation:g=
14、rotating radius,cm r min2 1.118 105Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 8.Recovery of Pigment for Analysis8.1 The pigment may be completely recovered from thecentrifuge bowl and washed to remove residual vehicle.Thismay be done
15、 either by a Soxhlet extraction or washing thepigment with a suitable solvent and recentrifuging.NOTE2It has been noted that the removal of the pigment from thebowl of a Sharples supercentrifuge can be facilitated by lining the bowlwith a piece of polyester film prior to adding the sample and subseq
16、uentlyjust slipping the polyester film along with the pigment out of the bowl.9.Precision and Bias9.1 PrecisionThe precision estimates are based on aninterlaboratory study of this test method in which air dryingmaterials were analyzed in duplicate or triplicate.The follow-ing criteria should be used for judging the acceptability ofresults at the 95%confidence level:9.1.1 RepeatabilityThe difference between two results,each the mean of duplicate determinations obtained by thesame operator,will ap
