Abstract
Knowledge of the depth of the evaporation front (place in porous materials where evaporation occurs) is important in the study of weathering processes and the description of places where weathering occurs or will occur in the future. The evaporation front is almost imperceptible in terms of moisture measurement, and therefore it is very difficult to detect it by completely non-destructive methods, which also require laboratory conditions.
This function sample allows the determination of the depth of the evaporation front, the measurement is repeatable and minimally destructive, and there is no undesired colouring of the measured material. The function sample consists of a probe made of a porous polymer clay with a diameter of about 2 mm that is inserted into the material of interest, then removed and inserted into a pre-prepared container with Na-fluorescein in powder form and interpretated.
At the place of capillary water presence in the material, adhesion and partial dissolution of Na-fluorescein occurs on the probe, at the place corresponding to the dry material, the probe remains in its original form. The location of the evaporation front is then interpreted as the interface between the two parts of the probe.
The proposed method has the potential for use in construction, including monitoring on buildings of cultural heritage, but also, for example, in geomorphology. The functional sample was financed and designed within the solution of the sub-project "Development of a probe for detection of liquid water in historical building materials" with state support of the Technology Agency of the Czech Republic under the GAMA2 Program, No.
TP01010040 "Support of the commercialization process of research and development at Charles University".