A bulk sample is reduced by a mechanical process until a reduced sample is obtained. The reduced sample may be used for the following purposes: a) the preparation of a final sample or a laboratory sample of mass greater than 250 g from a blended bulk sample of mass greater than 500 g; b) the preparation of several equivalent laboratory samples and/or reference samples and/or storage samples, each of a mass greater than 250 g, from a final sample; c) the preparation of a test sample from a loboratory sample.