ASTM_D_4838_-_88_2010.pdf

Designation:D483888(Reapproved 2010)Standard Test Method forDetermining the Relative Tinting Strength of ChromaticPaints1This standard is issued under the fixed designation D4838;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 describes the determination of theabsorption tinting strength of a chromatic test paint relative tothat of a standard or reference paint of the same chemical type.The procedures are based on dilution of the paints with astandard mixing white paint,followed by instrumental mea-surement and calculation.Provision is made for correcting theresults for small differences in hue or chroma,or both,betweenthe test and reference chromatic paints.1.2 This test method is intended for the comparison ofpaints containing the same type of vehicle(acrylic,alkyd,oroil)and single-pigment colorants of the same Colour Index2name and number.The amounts of the pigment and of the othercomponents of the paint need not be known.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 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:3D1640 Test Methods for Drying,Curing,or Film Formationof Organic Coatings at Room TemperatureD4303 Test Methods for Lightfastness of Colorants Used inArtists MaterialsE284 Terminology of AppearanceE308 Practice for Computing the Colors of Objects by Usingthe CIE SystemE1164 Practice for Obtaining Spectrometric Data for Object-Color Evaluation3.Terminology3.1 Definitions:3.1.1 tinting strength,nmeasure of the effectiveness withwhich a unit quantity of a colorant alters the color of a material.For scattering and absorbing colorants(pigments),both ab-sorption and scattering tinting strength must be specified.3.1.2 tinting strength,absorption,nrelative change in theabsorption properties of a standard white material when aspecified amount of an absorbing pigment,black or chromatic,is added to it.3.1.2.1 DiscussionThis is the common definition of tint-ing strength;however,this definition of the term can bemisleading.For example,the tinting strength of a yellowcolorant depends on its scattering as well as its absorption.Itstinting strength as determined from a mixture with whiteprovides no information about its behavior when mixed withlow-scattering colorants,such as a black.3.1.3 tinting strength,scattering,nrelative change in thescattering properties of a standard black material(with nowhite pigment present)when a specified amount of a white orchromatic scattering pigment is added to it.3.1.4 For other definitions,see Terminology E284.3.2 Definitions of Terms Specific to This Standard:3.2.1 drawdown,na layer of paint deposited on a substrateby use of a drawdown bar to evaluate the characteristics of thepaint.3.2.2 drawdown bar,na bar designed to deposit a speci-fied thickness of wet paint film uniformly on a specified testpanel or other substrate.4.Summary of Test Method4.1 Chromatic paints are diluted with white paint to obtainmixtures that will produce a drawdown having 35 to 45%reflectance factor at the wavelength of maximum absorption.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.57 on Artist Paints and Related Materials.Current edition approved June 1,2010.Published July 2010.Originally approvedin 1988.Last previous edition approved in 2003 as D4838-88(2003).DOI:10.1520/D4838-88R10.2Colour Index,The Society of Dyers and Colourists,London,1987.Availablefrom the American Association of Textile Chemists and Colorists,P.O.Box 12215,Research Triangle Park,NC 27709.3For 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 4.2 Drawdowns of these mixture paints are produced atcomplete hiding.4.3 The drawdowns are measured to obtain tristimulus filterreadings R,G,B either directly or by computation from CIEtristimulus values X,Y,Z.4.4 One of the samples is designated the standard,and thepercents of tinting strength,%TS,of the others are calculatedrelative to that of the standard.Provision is made for correctingthis tinting strength for small differences in hue,chroma,orboth,between