4.1 Several test methods for carbon black require the reduction in sample size or the blending of the test sample to reduce the variation of the measured characteristic. Other factors being equal, larger samples will tend to be more representative of the total supply. This practice provides procedures for reducing the large sample obtained from the bag and bulk sampling practices to a convenient size for conducting a number of tests to describe the material and measure its quality in such a manner that the smaller portion is most likely to be a representation of the bulk sample. Failure to follow the procedures in this practice could result in providing a nonrepresentative sample to be used in subsequent testing. Individual test methods provide for minimum amounts of material to be tested.

4.2 Test Method A, Reduction of Sample Size, is typically used to obtain an aliquot from a large sample, splitting a black into two or more equal portions, or reducing a blended black from Test Method B to a specified sample size. The final sample is always smaller than the original sample and would not be considered to be a "well blended" sample.

4.3 Test Method B, Blending of Carbon Black, is typically used to prepare a homogeneous sample. The homogeneous sample may be used for several tests (see Note 2) or may be reduced in size by Test Method A. The final sample size is the same as the original.

4.4 When a sample is to be blended and reduced, the sample should be blended (Test Method B) before reduction (Test Method A). The blending and reduction must be done before the sample is dried (Test Method C).