A subsample (also known as an "increment") is a small portion of a larger amount of bulk material that is taken for analysis. Bulk sampling often involves taking multiple subsamples from different parts of the set to create a representative total sample (or "composite sample") of the entire material.
Taking multiple subsamples is important because bulk materials are often heterogeneous and can have differences in composition over the entire volume of the material. By taking multiple subsamples from different parts of the set, it can be ensured that the composite sample represents the entire amount of bulk material and not just a small part of it.
The exact number and location of the subsamples to be taken may vary depending on the type of bulk, the specific requirements of the sampling, and applicable standards and guidelines. It is important to follow appropriate sampling procedures and correctly handle and process the subsamples to ensure that the composite sample is representative and provides accurate test results.