Cultural heritage preservation
The use of dyes in buildings of cultural heritage is not recommended due to its aesthetic drawbacks. The uranine-probe method is applicable and used in geomorphology but its application in heritage preservation is greatly limited by its properties, which is incompatible with monument protection. Therefore, a new version of the moisture-probe is under development.
Cavernous weathering research
Numerous processes cause rock weathering, but why is decay in caverns faster than around them? The long-awaited answer to this question was suggested by Huinink et al. (2004) when they published their model of honeycomb weathering. According to the model, when pore water evaporates, dissolved ions start to precipitate as salts in the place of evaporation. Crystallization pressure then disrupts the rock, which consequently decays. The place of (sub-surface) evaporation is called the evaporation front. If the water flux from the rock interior is high enough, the evaporation front remains at the surface. The behaviour of capillary water flow in honeycombs was confirmed on real sandstone honeycombs from a continental climate, which shows that the position of the evaporation front predetermines whether a surface will be smoothed or develops into honeycombs. For this reason, it is critically important to measure the depth of the evaporation front in rocks as part of any cavernous weathering research.
The challenge of measuring rock moisture
According to our research, the moisture probes (uranine-probe and polymerclay probe) are the most suitable methods for determining the depth of the evaporation front. These methods can be accompanied by relative humidity sensors. For other applications of measuring rock mositure see our publication Weiss and Sass (under review).