A clay sample (powder) was tested in air using a TMA-MS (Aëolos Quadro) coupling in the temperature range from RT to 800°C. At the beginning of the measurement, the adsorptively bound water and the interlayer water are released (shrinkage of 0.01%). Above 300°C, the sample’s organic constituents burn up (maxima in the curves for m18, water, and m44, CO2). There is no visible influence on the expansion curve here, due to the very low proportion. Between 487°C and 536°C, dehydroxylation of the sample’s clay mineral content takes place. Associated with that is a sample shrinkage of 0.05%.