For several years now, the Franciscans and various experts have been working on a thorny problem: the erosion of the Grotto of the Annunciation. A site that has been venerated since the time of the first Christians, touched and remodeled by the hands of so many pilgrims, this limestone cave has suffered heavy shocks to its chemical equilibrium. As proof of the urgency, Fr Kaswalder, who has been following the situation, reports that “in one year, the grotto has retreated 5 cm,” and he adds, “at that rate, the grotto will be no more in fifty years!”
Like all grottos, the ecosystem of the Nazareth grotto relies on temperature, hygrometry (atmospheric humidity), and gas exchange. The various specialists are decisive: the erosion of the grotto comes from excess humidity due to two factors, one external and the other internal.
The external factor is caused by pilgrims perspiring and exhaling. The latter causes a carbonic acid saturated humidity that attacks the limestone walls and ends up irreparably destroying them. For this reason, the grotto was closed to the public with an iron grille that was forged in 2006. At the same time, the lighting was replaced by a cold light system.
In spite of the many repairs, cleanings and palliative treatments to the rock, “the humidity and other signs return unceasingly, even though not even one drop of rain has entered the grotto”.
As a result, the friars of the Custody have been delving into the internal and geologic causes of the phenomenon. They are assisted and guided in this by a new team of experts from the ACCO Solutions company of Bolzano, Italy. Specialists in dehumidification, they first studied, documented and explained the rising humidity due to capillarity (wicking). In concrete terms, this means that in several places at various depths in the floor of the grotto there is an accumulation of water that has no exit and causes “ascending humidity”. Having already studied numerous villas, museums, castles and churches, such as the prestigious Basilica of Santa Maria della Salute in Venice, ACCO Solutions proposed to the Custody that a series of modifications be made to create a lasting horizontal barrier that will effectively stop water from entering the wall structure.
Several months ago, therefore, a team of architects, geologists, restorers and humidity specialists began work. They started by cleaning the stains that were more or less everywhere, and then created drainage along the walls. The next job, as Fra Sinisha, the basilica’s sacristan, demonstrated, was to insert electrodes and capacitors in the little openings to detect and relay the presence and movement of humidity throughout the day. In this way, without any invasive or destructive intervention, the team plans to discover the origin of the phenomenon in order to curb it, “a real miracle we no longer believed could happen,” says Fra Kaswalder. At the same time, taking advantage of an electro-physical phenomenon, the electrodes connected to a small electric power plant will literally fight the water’s natural power. As a whole, it will all function as a battery with the floor as the anode (positive pole) and the walls of the grotto as the cathode (negative pole). The water, displaced from the positive to the negative poles, will be reversed by the electrical discharge.
If the expertise and discretion of the team charmed the friars, they are even more taken by their proposal to help find funding for the project. Several religious, private and public partners have already been found in Italy, signs of good will that permit a more serene view of the grotto’s future. The friars, however, are aware of the damage that has already occurred. Fra Bruno, superior of the basilica, recently said in an interview that “the experts can only promise us to stabilize the ecosystem, saving what remains of the living portion of the grotto.” In a few months the results of the work will be measured and the Franciscans, who have been caring for the site since 1620, will know if they stopped the destructive effects of humidity.
E.R.
Like all grottos, the ecosystem of the Nazareth grotto relies on temperature, hygrometry (atmospheric humidity), and gas exchange. The various specialists are decisive: the erosion of the grotto comes from excess humidity due to two factors, one external and the other internal.
The external factor is caused by pilgrims perspiring and exhaling. The latter causes a carbonic acid saturated humidity that attacks the limestone walls and ends up irreparably destroying them. For this reason, the grotto was closed to the public with an iron grille that was forged in 2006. At the same time, the lighting was replaced by a cold light system.
In spite of the many repairs, cleanings and palliative treatments to the rock, “the humidity and other signs return unceasingly, even though not even one drop of rain has entered the grotto”.
As a result, the friars of the Custody have been delving into the internal and geologic causes of the phenomenon. They are assisted and guided in this by a new team of experts from the ACCO Solutions company of Bolzano, Italy. Specialists in dehumidification, they first studied, documented and explained the rising humidity due to capillarity (wicking). In concrete terms, this means that in several places at various depths in the floor of the grotto there is an accumulation of water that has no exit and causes “ascending humidity”. Having already studied numerous villas, museums, castles and churches, such as the prestigious Basilica of Santa Maria della Salute in Venice, ACCO Solutions proposed to the Custody that a series of modifications be made to create a lasting horizontal barrier that will effectively stop water from entering the wall structure.
Several months ago, therefore, a team of architects, geologists, restorers and humidity specialists began work. They started by cleaning the stains that were more or less everywhere, and then created drainage along the walls. The next job, as Fra Sinisha, the basilica’s sacristan, demonstrated, was to insert electrodes and capacitors in the little openings to detect and relay the presence and movement of humidity throughout the day. In this way, without any invasive or destructive intervention, the team plans to discover the origin of the phenomenon in order to curb it, “a real miracle we no longer believed could happen,” says Fra Kaswalder. At the same time, taking advantage of an electro-physical phenomenon, the electrodes connected to a small electric power plant will literally fight the water’s natural power. As a whole, it will all function as a battery with the floor as the anode (positive pole) and the walls of the grotto as the cathode (negative pole). The water, displaced from the positive to the negative poles, will be reversed by the electrical discharge.
If the expertise and discretion of the team charmed the friars, they are even more taken by their proposal to help find funding for the project. Several religious, private and public partners have already been found in Italy, signs of good will that permit a more serene view of the grotto’s future. The friars, however, are aware of the damage that has already occurred. Fra Bruno, superior of the basilica, recently said in an interview that “the experts can only promise us to stabilize the ecosystem, saving what remains of the living portion of the grotto.” In a few months the results of the work will be measured and the Franciscans, who have been caring for the site since 1620, will know if they stopped the destructive effects of humidity.
E.R.