ASTM_D_6531_-_00_2010.pdf

Designation:D653100(Reapproved 2010)Standard Test Method forRelative Tinting Strength of Aqueous Ink Systems byInstrumental Measurement1This standard is issued under the fixed designation D6531;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 procedure for determiningthe relative tinting strength of waterbased ink systems using acomputer-aided spectrophotometer.1.2 This test method is applicable to waterbased printinginks and bases to be used primarily in flexographic and gravureprinting applications.1.3 This test method applies only to single,non-fluorescentpigmented colors and black ink systems for which there is areference standard containing a pigment of the identical colorindex name and number.1.4 The procedure in this test method specifies placingtinted samples in a cuvette for spectrophotometric measure-ments.The use of thick wet drawdowns as in Test MethodsD2066 are inappropriate due to severe floating problems withaqueous systems.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 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.2.Referenced Documents2.1 ASTM Standards:2D2066 Test Methods for Relative Tinting Strength of Paste-Type Printing Ink DispersionsD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1331 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 Definitions related to color differences are covered inPractice D2244.The definitions of tinting strength terms aregiven in Test Methods D2066.4.Summary of Test Method4.1 A standard and unknown samples are each reduced tothe same concentration in a white tinting base then dispersedon a paint shaker.4.2 The dispersed samples are transferred to cuvettes forreflectance measurements on a spectrophotometer.Hue andstrength relative to the standard tint are computed.NOTE1The hue readings indicate the closeness of the unknownsample to that of the standard.5.Significance and Use5.1 Tinting strength is an essential property of printing inkdispersions.Although results on bulk tints do not guaranteeequivalency of dry printed films,they provide useful param-eters for quality control of production batches of bases andfinished inks.Test results may also be used for color matchingpurposes.6.Apparatus6.1 Glass Jars,capacity approx.64 g,33 mm in diameter by70 mm in height,with screw cap lids.6.2 Paint Shaker.6.3 Spectrophotometer,with small-area view(10-mmaperture,diffuse/8 geometry)and with a computer and soft-ware to measure reflectance factor,calculate color differencesby CIELAB 1976 equation.Tinting strength is calculated by a1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.56 on Printing Inks.Current edition approved Dec.1,2010.Published December 2010.Originallyapproved in 2000.Last previous edition approved in 2005 as D6531 00(2005).DOI:10.1520/D6531-00R10.2For 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 Kubelka-Monk equation transformed from the lowest tristimu-lus value.Alternate instrumentation and software may be usedby agreement between producer and user,or different plantlocations.6.4 Disposable Cuvettes,10 mm in diameter,with at leastone optically true face.6.5 Disposable Pipettes 7-mL capacity,3.5-mL bulb drawor suitable substitute.6.6 Balance,capacity 100 g,accurate to 10 mg,preferably1 mg.6.7 Black Electrical Tape.6.8 Black Cover,90 mm in diameter such as 1-lb ink can,with interior painted flat black.6.9 Ink Knives,small.6.10 Medicine Droppers.7.Materials7.1 Standard Ink or BaseThe standard should be 100%intended strength of the same pigmentation and similar inviscosity to the unknown sample.7.2 White Tinting Base,compatible with and of a viscositysimilar