ASTM_D_4584_-_05_2022.pdf

Designation:D458405(Reapproved 2022)Standard Test Method forMeasuring Apparent pH of Electrocoat Baths1This standard is issued under the fixed designation D4584;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 measurement of the freehydrogen ion concentration of electrocoat baths and theirultrafiltrates.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 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established 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:2D1193 Specification for Reagent WaterD1293 Test Methods for pH of WaterE70 Test Method for pH of Aqueous Solutions With theGlass ElectrodeE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)33.Summary of Test Method3.1 A specimen of a well-agitated electrocoat bath is placedin a stirrer-equipped container and the pH measured with a pHmeter and associated glass and reference electrodes.4.Significance and Use4.1 The pH is the measure of the free hydrogen ionconcentration of a sample,and it indicates whether an electro-coat bath is acidic,neutral,or basic.Since pH measurements ofgood precision are made in aqueous solutions,it is suggestedthat the pH measurements of electrocoat baths are onlysemi-quantitative,and therefore such measurements should bereferred to as apparent pH measurements.4.2 The pH of electrocoat paints is used for research,production,and quality control or electrocoat bath processcontrol.4.3 Other related methods for determining the pH of wateror aqueous systems are described in Test Methods D1293 andE70.5.Apparatus5.1 pH Meter.5.2 Glass and Reference Electrodes.NOTE1Due to the polarity of electrocoat materials it is desirable touse a separate set of electrodes for each bath polarity,cathodic and anodic,because a bath of opposite polarity poisons the electrodes.A desiredpractice is to rinse the electrodes after each measurement with anappropriate solvent for the electrocoat material.5.3 Thermometer,capable of 0.5 C accuracy with a 2 to32 C range.6.Reagents6.1 Reference Standard Solutions,commercial standards ofpH 4.0,7.0,and 10.0.6.2 Purity of WaterReferences to water shall be under-stood to mean water conforming to Type II of SpecificationD1193.7.Sampling and Sample Preparation7.1 The sample should be obtained while the electrocoatbath is under proper circulation so that a uniform material isobtained.In case of an ultrafiltrate,the material should bethoroughly mixed or stirred prior to sampling to assureuniformity.7.2 After sampling and prior to removing a test specimen itis mandatory that the sample be shaken or stirred until it is1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved June 1,2022.Published July 2022.Originally approvedin 1986.Last previous edition approved in 2015 as D4584 05(2015).DOI:10.1520/D4584-05R22.2For 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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,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 Organization Technical Barriers to Trade(TBT)Committee.1homogeneous and free of any settled material.This is particu-larly important if there is any delay between the sampling ofthe bath and the preparation of the specimens for the test.Theabsence of settled material can be ascertained visually(in atransparent container)or by inserting a spatula,scraping thebottom of the container