The Roman city of Aquileia was founded in 181 BC by a handful of legionaries on the march to defend the borders of the empire from the barbarian invasions. Thanks to its strategic position, the military post soon turned into a thriving city, an essential intersection for the trade routes of Rome.
Some evident signs of its ancient greatness remain up to these days: the archaeological findings clearly show a past full of richness, the foundations of buildings design the plan of the ancient city. And among the walls, there are still intact mosaics characterised by an extraordinary beauty.
These huge archaeological areas, however, are not exempt from suffering the ravages of time. The delicate materials, which have survived more than two thousand years of history, are affected by natural elements, water, wind and biological infestations.
The company Arecon Restauri has been commissioned to carry out the special conservation cleaning of the area known as ‘Fondi Cal’, a large space in which the original floors of Roman dwellings are still preserved among the ancient foundations and low walls.
The company has decided to use IBIX air-blasters for cleaning the delicate stones of the low walls. The method is based on the controlled, low-pressure projection of extra-fine inert material that is able to remove biological infestations and smog, while also protecting the noble patina of stones.
For greater gentleness, restorers have decided to employ the HELIX helical vortex technology, an original patent. The tool is able to apply a rotary movement to the inert material coming out of the air-blaster gun. In this way, the jet does not reach the treated surface perpendicularly, but rather always in a tangent direction; the rotating movement also contributes to the removal of harmful coatings (patinas). Thus, the intervention becomes softer but, at the same time, more effective. On this type of applications, the use of the HELIX technology guarantees a 30% increase in effectiveness as well as considerable savings in terms of the material used.
Whereas as regards the cleaning of the precious mosaic tiles, a different procedure had to be followed. The first operation carried out consisted in a biocidal treatment, which was necessary in order to dry mould, fungi and other biological infestations that would otherwise appear again short after the cleaning treatment.
After this first phase, the floor tiles that were not firmly attached were removed. This was done in order to prevent the treatment from damaging the small tiles or from removing them, causing their loss.
Then, it was decided to apply the cryogenic technique, i.e. the projection of Co2, dry ice, on the surfaces to be cleaned. For this operation, the IB-ICE equipment, also supplied by IBIX, was used. Unlike traditional cryogenic cleaning, which is mainly used in the industrial sector, IBIX has developed a low pressure (3 bar) intervention parameter that has made cryogenic cleaning much more delicate and economical than the standard interventions. As a matter of fact an IB 2000 compressor supplied by IBIX was employed. Such compressor is able to supply 2000 litres of air per minute (this power is extremely lower than the one regularly used for interventions with cryogenic technology). Thanks to these adaptations, a generally aggressive technique has been turned into a suitable procedure for a delicate restoration intervention.
A characteristic of the cryogenic method, which made this technique particularly suitable for the restoration of the findings in Aquileia, is that it does not leave any residues during the cleaning operation. This was one of the main problems to be faced in the ‘Fondi Cal’ intervention; in fact, any technique that would generate even the slightest waste would have compromised the delicate mosaics, which are precisely made up by typical interstices between the small tiles from which it would have been impossible to remove cleaning residues afterwards.
Another feature that has made the IBIX system particularly suitable for the work in the archaeological site lies in the fact that all the technologies used have been transported to the area with a commercial van of average dimensions. In addition, all the machines are wheeled, light and easy to carry around and transport, thus ideal to work in the difficult spaces of archaeological sites and excavations.
[di Fabrizio Settanni]
Special thanks to the Friuli Venezia Giulia Landscape and Cultural Heritage Regional Head Office for granting the images. The restoration of the archaeological site "Fondi Cal" was organized and funded by the Aquileia Foundation. The works were performed by the company “Arecon – Arte Restauro Conservazione”