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. 2012 May 22;6(1):47.
doi: 10.1186/1752-153X-6-47.

The Altar Machine in the Church Mother of Gangi (Palermo, Italy). Interpretation of the past uses, scientific investigation and preservation challenge

Angela Lo Monaco  1 , Maurizio Marabelli, Claudia Pelosi, Michele Salvo
Affiliations

The Altar Machine in the Church Mother of Gangi (Palermo, Italy). Interpretation of the past uses, scientific investigation and preservation challenge

Angela Lo Monaco et al. Chem Cent J. .

Abstract

Background: The aim of this work was to study the Altar Machine in the Church Mother of Gangi, a little town near Palermo (Italy) regarding the history, the technical manufacture, the constitutive materials and the state of preservation.The Altar Machine was dated back to the second half of the 18th century; it is constituted by carved and painted wood, a complex system of winch and pulleys allows move various statues and parts of the Machine in accordance with the baroque scenography machineries.

Results: The observation and survey of the mechanisms allowed formulate hypothesis on a more ancient mode of operation of the Altar Machine.Laboratory analysis revealed the presence of many superimposed layers constituted by several different materials (protein binders, siccative oils, natural terpene resins, shellac, calcium carbonate, gypsum, lead white, brass, zinc white, iron oxides) and different wood species employed for the original and restoration elements of the Machine. This is due to a continuous usage of the object that has got a demo-ethno-anthropological significance.Microclimate monitoring (relative humidity RH and temperature T) put in evidence that most of the data fall outside the tolerance intervals, i.e. the RH and T limits defined by the international standards. In particular, T values were generally high (out of the tolerance range) but they appeared to be quite constant; on the other hand RH values fell almost always inside the tolerance area but they often exhibited dangerous variations.

Conclusions: The characterization of the constitutive materials provided useful information both to support the dating of the Machine proposed by the inscription and to obtain a base of data for a possible conservation work.The microclimate monitoring put in evidence that the temperature and relative humidity values are not always suitable to correctly preserve the artefact. The careful in situ investigation confirmed an on-going climate induced damage to the Altar Machine that, associated to the deterioration caused by its usage, may have dramatic consequences on this unique and peculiar work of art.The results of this work will have potential implications in the near future regarding a probable conservation project on the Machine.

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Figures

Figure 1
Figure 1
A view of the main altar of the Church Mother in Gangi (Italy).
Figure 2
Figure 2
A general view of the Altar Machine, front and back. The Holy Trinity painting is also visible.
Figure 3
Figure 3
A virtual reconstruction of the Machine with the supposed opening and the San Nicola statue that moves forward.
Figure 4
Figure 4
Some details of the damages in the Altar Machine.A) xylophages attack and scratches due to the use; B) xylophages attack and wood erosion; C) various kinds of stains and dirt layers; D) xylophages attack in the choir that encircles the Altar.
Figure 5
Figure 5
Microphotographs of samples ASN1 (A, B), ASN2 (C, D), ASN4 (E, F) and ASN5 (G, H), under reflected light (A, C, E, G) and UV fluorescence (B, D, F, H).
Figure 6
Figure 6
FTIR spectrum of sample ASN1.
Figure 7
Figure 7
Graph of the temperature against time over the entire monitoring period.
Figure 8
Figure 8
Graph of the relative humidity against time over the entire monitoring period.
Figure 9
Figure 9
T and RH performance and failure index in the tolerance matrix. The grey area defines the tolerance area for painted wood, painted wood sculptures, painted panels, according to UNI10829.
See this image and copyright information in PMC

References

    1. Salvo M. La “Macchina d’Altare” della Chiesa Madre di Gangi (PA). Studio conservativo. Specialization thesis. Tuscia University of Viterbo, Department of Cultural Heritage Sciences, ; 2009.
    1. Farinella S. La Chiesa dello Spirito Santo in Gangi: fabbricazione, trasformazioni e fatti d'arte dal 1576 attraverso i documenti inediti. Valdemone, Nicosia (Italy); 1999.
    1. Farinella S. Filippo Quattrocchi, gangitanus sculptor: il senso Barocco del movimento. Publisicula, Palermo (Italy); 2004.
    1. Camuffo D, Fassina V, Havermans J. Basic environmental mechanisms affecting cultural heritage. Nardini, In Kermes Quaderni. Firenze; 2010.
    1. Agresti G, Genco G, Giagnacovo C, Pelosi C, Lo Monaco A, Castorina R. Wood of chestnut in cultural heritage. Acta Horticulturae. 2010;866:51–57.

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