Abstract: A method and an LWIR imaging system for detecting an amorphous and/or crystalline structure of phosphate and/or sulphate salts on the surface of a substrate or within a substrate are described. The method comprises the steps of i) providing an LWIR imaging system, the LWIR imaging system comprising a) an infrared light emitting source (A) that emits over the whole range of 8 to 14 micrometers, b) an LWIR detecting device (B) and c) a ToF distance sensor (C), ii) providing a substrate comprising an amorphous and/or crystalline structure of phosphate and/or sulphate salts on the surface of the substrate or within the substrate, ii) irradiating the provided substrate with the infrared light emitting source and iii) detecting, with the LWIR detecting device and using and/or based on the TOF distance sensor, the intensity of electromagnetic radiation scattered, emitted and/or reflected by the substrate and the amorphous and/or crystalline structure of phosphate and/or sulphate salts.