ASTM_D_2448_-_85_2012.pdf

Designation:D244885(Reapproved 2012)Standard Test Method forWater-Soluble Salts in Pigments by Measuring the SpecificResistance of the Leachate of the Pigment1This standard is issued under the fixed designation D2448;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 parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of the specificresistance of the aqueous leachate from a pigment as an indexof water-soluble salt content.This test method is applicable towhite pigments and colored pigments(organic and inorganic).The water-soluble salts content is a function of the specificresistance of the solution formed by extracting the pigmentwith water.1.2 This test method is based on a water to pigment ratio of9+1.The leachate yield(minimum 160 mL)sufficient forrinsing the cylinder dip cell and thermometer plus the mini-mum 80 mL required for the measurement to determine thequantity of pigment to be used.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 This 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 Documents2.1 ASTM Standards:2D1193 Specification for Reagent Water3.Summary of Test Method3.1 A weighed quantity of pigment is added to water andboiled.For hydrophobic pigments methyl alcohol is used tofacilitate wetting.After filtration,the specific resistance of thefiltrate is determined using a conductivity bridge.4.Significance and Use4.1 This test method provides a reliable means for thedetermination of the relative amounts of these salts whencomparing different lots of the same pigment grade.Water-soluble salts also affect the water resistance and blister resis-tance of coatings,especially primers for steel.Conductivitymeasurements,however,cannot be used as the only method todetermine and compare the amount of water soluble salts ofpigments with the same chemical composition but produced bydifferent manufacturing processes.5.Apparatus5.1 Centrifuge(optional),having a 500-mL capacity percup.5.2 Filter Paper(Note 1)For high reliability avoid use offilter paper containing soluble material.Each filter should bewashed with reagent water in the funnel until resistance of thefiltrate is greater than 200 000 cm.NOTE1The size of the filter paper will be determined by howvoluminous the pigment is.Some organic pigments require at least a185-mm paper for proper filtering.5.3 Filter Aid(optional)The use of a filter aid may bedesirable with some pigments to improve filtration.However,the filter aid must be treated to meet the same specifications forfilter paper as given in 5.2.5.4 Ungraduated Cylinders,approximately 35 mm wide by125 mm deep.5.5 Thermometer,graduated in 0.2C intervals.5.6 Conductivity Bridge.35.7 Conductivity Cell,3having a cell constant,K,of 1.Thecell constant recommended for various ranges of electrolytes isas follows:5.7.1 For specific resistances of less than 250 cm,use acell with a constant of 10 or more.5.7.2 For specific resistances from 250 to 200 000 cm,use a cell with a constant of 1.This covers the range for mostpigments.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.31 on Pigment Specifications.Current edition approved Nov.1,2012.Published November 2012.Originallyapproved in 1966.Last previous edition approved in 2007 as D2448 85(2007).DOI:10.1520/D2448-85R12.2For 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.3Any commercially produced conductivity bridge and conductivity cell issatisfactory.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.7.3 For specific resistances of reagent water or of over200 000 cm,use a cell with a constant of 0.1.6.Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mea