Wet chemical analysis of raw materials

These analyses are mainly performed on natural raw materials, notably on clay. The user of this clay is always interested in the mass percentage Fe, Ca and humus and in the mass percentage loam, fine sand and coarse sand. The contents of iron and calcium affect the baking colour and other contents are of influence on the properties of the mass as far as moulding and drying and firing behaviours are concerned. Furthermore we have learnt from the chapter on clay that this material may contain many more components which sometimes also need to be determined, for instance for environmental reasons. 

Natural ceramic raw materials have the disadvantage that they are not soluble in water and consequently unsuitable for wet chemical analysis. That is why they are first destructed in the laboratory. Destruction means that a substance or a mixture of substances is heated together with a substance or a mixture of substances and as a result the component to be destructed is largely separated into ions and consequently dissolves in water. The destruction method and the substances are specific for the substance undergoing the destruction. Different methods applied to the same substance lead to different results. 

Examples of destructive agents are a solution of HF (for most silicates), molten sodium carbonate (Na2C03) and molten potassium disulphate 

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