ASTM_D_6131_-_97_2012.pdf

Designation:D613197(Reapproved 2012)Standard Test Method forEvaluating the Relative Tint Undertone of Titanium DioxidePigments1This standard is issued under the fixed designation D6131;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 is intended to be used to determine thetint undertone(blue or yellow)of titanium dioxide pigments.This relates to the effective particle size of the pigment.It isbased upon tinting with a black iron oxide,but other blacksmay be used if found suitable.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D16 Terminology for Paint,Related Coatings,Materials,andApplicationsD2745 Test Method for Relative Tinting Strength of WhitePigments by Reflectance MeasurementsE313 Practice for Calculating Yellowness and WhitenessIndices from Instrumentally Measured Color CoordinatesE1331 Test Method for Reflectance Factor and Color bySpectrophotometry Using Hemispherical GeometryE1347 Test Method for Color and Color-Difference Mea-surement by Tristimulus ColorimetryE1349 Test Method for Reflectance Factor and Color bySpectrophotometry Using Bidirectional(45:0 or 0:45)Geometry3.Terminology3.1 Any special terms used in this test method can be foundin Terminology D16.4.Summary of Test Method4.1 Titanium dioxide pigments are dispersed in a black pastewith a mechanical muller.Test and reference pigments aretreated identically.The resultant grey pastes are applied toglass cover slips and read instrumentally.These readings arethen used to calculate the yellowness index.5.Significance and Use5.1 This test method allows the user to make a quickdetermination of the blueness or yellowness of the tint under-tone of titanium dioxide pigments,versus a reference pigmentagreed upon by the parties to the test.This is an importantmeasure of tone,since it gives both a measure of effectiveparticle size,and quick approximation of the blue/yellowundertone that can be expected when a coating containing thetitanium dioxide is tinted.5.2 Such matters as the vehicle for preparing the disper-sions,and the black for tinting have been suggested.However,changes in the components may be made by agreementbetween the buyer and the seller.5.3 The results obtained with a mechanical muller do notnecessarily correlate directly with a practice where differentdispersion conditions exist.However,dispersion with a me-chanical muller is a quick and inexpensive way of evaluatingthe undertone of a titanium dioxide pigment.6.Apparatus6.1 Balances,meeting the requirements of Test MethodD2745.6.2 Mechanical Muller,equipped with ground-glass platesto which a variable but known force may be added in 220Nincrements.The driven glass plate shall have a speed ofrotation of between 70 and 120 r/min and the apparatus shallhave an arrangement for presetting the number of revolutionsin multiples of 50.6.3 Rubbing Surfaces,meeting the requirements of TestMethod D2745.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.26 on Optical Properties.Current edition approved June 1,2012.Published July 2012.Originally approvedin 1997.Last previous edition approved in 2004 as D6131 97(2004).DOI:10.1520/D6131-97R12.2For 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.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.4 Small Glass Slab,meeting the requirements of TestMethod D2745.6.5 Spatula,meeting the requirements of Test MethodD2745.6.6 Glass Cover Slips,No.2 thickness,45 by 50 mm.6.7 Color Measuring Instrument,meeting the requirementsof Test Methods E1331,E1347,or E1349,and having ameasuring port 25 mm or smaller in diameter.7.Materials7.1 Reference StandardA standard pigment as agreedupon between the buyer and the seller.7.2 Vehicle-Castor Oil,(Grade AA).7.3 Tinting PasteA Vehicle/Parts by Weight paste such asone of the following:(1)Castor Oil50Gypsum47Thickener6Iron Oxide Black3(2)Petroleum Jelly97Lampblack38.Procedure8.1 Disperse pigment into paste as described in Test MethodD2745.Luminance should be approximately 40%.8.2 Apply the gray paste to