1、Designation:D274500(Reapproved 2008)Standard Test Method forRelative Tinting Strength of White Pigments by ReflectanceMeasurements1This standard is issued under the fixed designation D2745;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revis
2、ion,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 procedure for determin-ing the relative tinting strength of white pigments b
3、y reflec-tance measurements of black tints.1.2 This test method is applicable only for comparing thetest pigment with a reference standard of the same type andgrade.NOTE1Test Method D332 describes a procedure for visual assess-ment of blue-tinted samples.1.3 The values stated in SI units are to be r
4、egarded 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 determi
5、ne the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D332 Test Method for Relative Tinting Strength of WhitePigments by Visual ObservationD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordi
6、nates3.Summary of Test Method3.1 Pigment is dispersed in a vehicle and let down withadditional vehicle that has been tinted.Dispersion and letdownare accomplished with a mechanical muller.Both the test andstandard pigments are treated identically.Opaque drawdownsare made of the paint and the Y trist
7、imulus values(green-filterreflectance)of the wet films are measured.The relative tintingstrength of the test pigment is calculated directly from thereflectance values.4.Significance and Use4.1 Tinting strength is one of the most important propertiesof a white pigment.This test method provides a mean
8、s oftesting this property for quality control.4.2 This test method is a referee method,and the vehicle forpreparing the dispersion and the black for tinting are suggested,but others may be used provided both the purchaser and theseller agree to the changes.4.3 The results obtained with a muller do n
9、ot necessarilyagree with industrial situations where different dispersingconditions exist.However,dispersing with a muller is a fast,relatively inexpensive way of testing tinting strength forroutine quality control.5.Apparatus and Materials5.1 Muller,automatic,equipped with a weight that exerts aper
10、manent 220-N(50-lbf)and an additional weight exerting a50-lbf making a total of 445-N(100-lbf).The two glass platesshall be kept sharp by removing from the machine and grindingthem face-to-face with No.303 optical emery or equivalent,and water.5.2 SpatulaA flexible spatula having a chromium-platedor
11、 plastic blade 75 to 150 mm(3 to 6 in.)long,and anotherwith a 75 mm(3-in.)tapered blade.5.3 Balances(1)A balance sensitive to 20 mg and(2)ananalytical balance sensitive to 0.4 mg.5.4 VehicleBecause the choice of vehicle may affectresults,a solvent-free vehicle(excluding refined or low-bodiedlinseed
12、oil)should be agreed upon by the purchaser and theseller.5.5 Tinting BlackA lamp black predispersed in a vehiclesimilar in nature to the test vehicle.Tinting black should beagreed upon between the purchaser and the seller.5.6 ChartEither gray or white lacquered charts cut to aconvenient size.1This t
13、est 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 Feb.1,2008.Published March 2008.Originallyapproved in 1968.Last previous edition ap
14、proved in 2000 as D2745 00.DOI:10.1520/D2745-00R08.2For 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
15、International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.7 Color Measuring Instruments,meeting the require-ments of Practice D2244.5.8 Film Applicator50 or 75 mm(2 or 3 in.)wide with aclearance of 150 m(6 mils)to produce wet films about 75 m(3 mils)thick.This
16、applicator when used as suggested in thetest method will produce an Rfilm.6.Standard6.1 Astandard white pigment of the same type as the sampleto be tested,as agreed upon by the purchaser and the seller.7.Procedure7.1 Place two concentric circles under the base plate of themuller so that they can be clearly seen through the plate.Thecircles can be drawn on a paper and inserted under the plate,orthey can be drawn directly on the underside of the bottomplate.The inner circle should be 63 mm(212in.)
