ASTM_D_6290_-_13.pdf

Designation:D629013Standard Test Method forColor Determination of Plastic Pellets1This standard is issued under the fixed designation D6290;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.Scope*1.1 This test method is intended primarily for the instru-mental measurement of the degree of yellowness(or change ofdegree of yellowness)under daylight illumination ofhomogeneous,nonfluorescent,nearly-colorless transparent ornearly-white translucent or opaque plastics.The measurementis made on pellets and based on tristimulus values obtainedwith a spectrophotometer or colorimeter.1.2 This test method is applicable to the color analysis ofplastic pellets.It is possible that each material will have uniquecharacteristics that determine the color values.1.3 This procedure outlines a method to determine colormeasurements,such as Yellowness Index,CIE X,Y,Z,andHunter L,a,b,or CIE L*,a*,b*.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.NOTE1There is no known ISO equivalent to this standard.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD2244 Practice for Calculation of Color Tolerances andColor Differences from Instrumentally Measured ColorCoordinatesE179 Guide for Selection of Geometric Conditions forMeasurement of Reflection and Transmission Propertiesof MaterialsE284 Terminology of AppearanceE308 Practice for Computing the Colors of Objects by Usingthe CIE SystemE313 Practice for Calculating Yellowness and WhitenessIndices from Instrumentally Measured Color CoordinatesE691 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 Refer to Terminologies D883 and E284 fordefinitions of terms used in this test method.4.Significance and Use4.1 Before proceeding with this test method,make referenceshould be made to the specification of the material being tested.Any test specimen preparation,conditioning,dimensions,ortesting parameters,or a combination thereof,covered in thematerials specification shall take precedence over those men-tioned in this test method.If there are no materialspecifications,then default conditions apply.NOTE2Some materials,such as polyamide(nylon),can be cooledvery differently during the production of the pellets.This variation in thecooling of the pellets can result in different levels of crystallinity in thepellets only.More crystalline nylons will be more opaque than amorphousnylons.This will result in differences in pellet opacity.The pellet shape isindependent of the crystallinity of the material.This variation in pelletappearance,due to varying levels of crystallinity,does not affect finalproperties.NOTE3This test method should not be used for general materialspecifications.4.2 This test method describes a technique useful for mak-ing color comparisons of resins in pellet form that is fast andconvenient as it does not require preparation,such as moldingor extruding specimens.The test method shall be used only tocompare specimens of similar pellet shape,size,texture,anddegree of translucency.For example,compare translucentdisc-shaped pellets to translucent disc-shaped pellets,not withopaque,rectangular shaped pellets.4.3 Exact measurements of resin pellet color are not neces-sarily directly related to the color of the final cast,molded orextruded product due to the multitude of variables,such as1This test method is under the jurisdiction of ASTM Committee D20 on Plasticsand is the direct responsibility of Subcommittee D20.40 on Optical Properties.Current edition approved Nov.1,2013.Published November 2013.Originallyapproved in 1998.Last previous edition approved in 2005 as D6290-051.DOI:10.1520/D6290-13.2For 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.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 producing variables,methods,and pellet shape and size.Colormeasurements can be useful for comparing resins in pellet formwhen all samples