Sieving is cost effective for particle sizes greater than 75 μ, although the technique can be used for some materials of smaller size if the method can be validated. Assuming the relevant standards and clean, wellmaintained equipment that conforms to the standards are used, sieving can provide an accurate and reproducible measure of particle size distribution within a sample.
SAMPLE PREPARATION IS NOT AN exact science; laboratory sub-sampling and sample splitting are prone to errors. These errors are due to heterogeneity either in the composition of the material, or in the non-random particle size distribution, which usually occurs as a result of gravitational forces. Any samples used for analytical testing must accurately reflect the composition of the original bulk material. If the initial particle size of the bulk material is too large, obtaining a representative sample is virtually impossible. (...)