Rough preparation of the analytical sample

Normally the sample to be analysed has to be taken from a larger piece of material. This operation must be carried out with all necessary care in order to avoid heating of the sample. This can not only result in oxidation of the surface, but, depending on the temperature and the metal, also in fairly deep penetration of surface contaminants into the sample. 

In general, a sharp metal saw is a suitable tool to carry out this preliminary operation. Abrasive wheels should only be used for very hard metals, whereas soft metals may also be sampled by e.g. careful cold rolling and punching. In every case, care must be taken that the sample surface is not fissured or smeared, but is smooth and has a bright appearance. If this is not the case, there is always a risk that contaminants penetrate deeply during the first stage of sample preparation, and that further finishing will not completely eliminate these contaminants. 

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