Thermochromic liquid crystal materials are commonly used in printing inks, opening up a wide range of possible applications. In order to ensure and control the most accurate application, the occurrence of the so-called colour play effect, i.e., the appearance of iridescent (rainbow) colours as a function of temperature, must be determined precisely. For this purpose, the temperature-dependent reflection of a sample must be measured using a spectrometer with an integrating sphere. The same values should be obtained for each sample containing the same thermochromic liquid crystalline material, irrespective of the spectrometer used, integrating sphere, layer thickness and the surface properties of the substrate. To describe this intrinsic property of the thermochromic liquid crystal material, the term communication mechanism might be considered. The research has shown how this mechanism is obtained experimentally.