Evaluation of corrective measures implemented for the preventive conservation of fresco paintings in Ariadne’s house (Pompeii, Italy)

Abstract

BackgroundA microclimate monitoring study was conducted in 2008 aimed at assessing the conservation risks affecting the valuable wall paintings decorating Ariadne’s House (Pompeii, Italy). It was found that thermohygrometric conditions were very unfavorable for the conservation of frescoes. As a result, it was decided to implement corrective measures, and the transparent polycarbonate sheets covering three rooms (one of them delimited by four walls and the others composed of three walls) were replaced by opaque roofs. In order to examine the effectiveness of this measure, the same monitoring system comprised by 26 thermohygrometric probes was installed again in summer 2010. Data recorded in 2008 and 2010 were compared.ResultsMicroclimate conditions were also monitored in a control room with the same roof in both years. The average temperature in this room was lower in 2010, and it was decided to consider a time frame of 18 summer days with the same mean temperature in both years. In the rooms with three walls, the statistical analysis revealed that the diurnal maximum temperature decreased about 3.5°C due to the roof change, and the minimum temperature increased 0.5°C. As a result, the daily thermohygrometric variations resulted less pronounced in 2010, with a reduction of approximately 4°C, which is favorable for the preservation of mural paintings. In the room with four walls, the daily fluctuations also decreased about 4°C. Based on the results, other alternative actions are discussed aimed at improving the conservation conditions of wall paintings.ConclusionsThe roof change has reduced the most unfavorable thermohygrometric conditions affecting the mural paintings, but additional actions should be adopted for a long term preservation of Pompeian frescoes.

Understanding the degradation of the blue colour in the wall paintings of Ariadne's house (Pompeii, Italy) by non‐destructive techniques

“…Rooms 7, 17 and 22 are protected from the direct exposure to rainwater and sunlight by recently installed roofs. [ 5 ] Room 7 is the south entrance and preserves a votive altar and mural paintings of the IV style. Room 17 is an ‘ oecus ’ and shows a well‐preserved mural painting of the III style.…”

“…The polycarbonate roofs initially installed in the 1970s, to protect the exposed paintings and mosaics from rainwater, were replaced in 2010, due to the thermal alterations they were causing (greenhouse effect). [5,6] Despite the efforts that have been made to protect this important house, noticeable alteration processes are still occurring. For instance, some rooms show clear evidences of damages provoked by biological colonization (macro and micro) and soluble salts formation (water infiltration, moisture and rain).…”

“…The polycarbonate roofs initially installed in the 1970s, to protect the exposed paintings and mosaics from rainwater, were replaced in 2010, due to the thermal alterations they were causing (greenhouse effect). [ 5,6 ]…”

“…For instance, some rooms show clear evidences of damages provoked by biological colonization (macro and micro) and soluble salts formation (water infiltration, moisture and rain). [ 1,5,7 ] In a few areas (e.g., Rooms 25 and 28), the damages are so critical as to cause the total loss of vast portions of mural paintings. In the case of Room 22 (also called blue room ; Figure 1), these problems are strongly changing the aspect of blue decorations (III style; Figure 2), causing colour variation in some areas (in comparison with the background colour), crystallization of salts as efflorescence and micro‐detachments of painting layers.…”

Raman imaging to quantify the thermal transformation degree of Pompeian yellow ochre caused by the 79 AD Mount Vesuvius eruption

“…However, some of the wall paintings of the houses that were excavated more than 100 years ago show different deterioration processes due to the exposure to the open modern atmosphere. In this sense, some works evidenced the deterioration of the Pompeian walls and wall paintings due to the formation of efflorescences [2,3] and darkening processes of red areas [4][5][6]. Although most of the detected pathologies took place after the recovery of the wall paintings, the acid gases and volcanic material at high temperatures emitted When goethite is thermally impacted at high enough temperatures, a dehydration reaction takes place.…”