More D Any test specimen preparation, conditioning, dimensions, or testing parameters, or a combination thereof, covered in the materials specification shall take precedence over those mentioned in this test method. If there are no material specifications, then default conditions apply. This variation in the cooling of the pellets can result in different levels of crystallinity in the pellets only.

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A number in parentheses indicates the year of last reapproval. The measurementis made on pellets and based on tristimulus values obtainedwith a spectrophotometer or colorimeter. It is possible that each material will have uniquecharacteristics that determine the color values. 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.

Referenced Documents2. Significance and Use4. 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. NOTE 2—Some 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. NOTE 3—This test method should not be used for general materialspecifications. 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. Current edition approved Nov. Published November Originallyapproved in United States1producing variables, methods, and pellet shape and size.

Colormeasurements can be useful for comparing resins in pellet formwhen all samples are similar in shape and size. This test methoddescribes a standard procedure on how these measurements aremade. See 6. It is important that similaroptical geometries be used if results are to be compared. Theseare designated as Groups defined as follows See Test Methods E andE NOTE 4—The clear sample holder may be any shape that is larger thanthe port with at least 6-mm between the edge of the port and the edge ofthe sample holder.

Use a centering device if one is provided by themanufacturer. NOTE 5—Care must be taken not to allow the pellet sample to remainat the measurement port for a long period of time prior to measurement. Light exposure of high intensity may cause yellowness to change, thusaltering the test value.

Precision and Bias Currently available through the U. All dataare based on a round robin conducted in inaccordance with Practice E, involving eight materialstested with six test results measured on three days by eachlaboratory.

For each material, pellets were gathered and pack-aged by one source and the individual packages were sent toeach of the laboratories which tested them.

Each test result isthe value of an individual determination. Each laboratoryobtained six test results for each materials. Table 1A and Table2B reflect the values as if each test value consisted of anaverage of three readings.

Warning—The following explana-tions of r and R It is not appropriate to rigorouslyapply the data in Table 1, Table 2, Table 1A, and Table 2Atoacceptance or rejection of material, as those data are specific tothe round robin and are not necessarily representative of otherlots, conditions, materials, or laboratories.

Users of this testmethod need to apply the principles outlined in Practice Eto generate data specific to their laboratory and materials orbetween specific laboratories. The principles of


ASTM D6290



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