From Ms R. de Angelis

I refer to the article “From the Vittoriosa clock tower to the restoration of paintings: the challenges and dilemmas of cultural heritage” by Noel Grima which mentions some contributions from the students’ conference organised by Heritage Malta in conjunction with Bournemouth University and the University of Malta (TMIS, 21 September).

I am very pleased to note that due importance is being given to raising awareness on the conservation of heritage sites and this article is definitely a step in the right direction.

I was one of the speakers at this conference and I presented the results of the research I undertook in 2002-2004, as part of an M.Phil. degree at the University of Malta, on the deterioration of the oil painting on stone by Giuseppe Calì in the dome of the Chapel of the Crucifix in the parish church of Cospicua.

I found this painting in an appalling condition and my research focused specifically on understanding why the painting was deteriorating.

In relation to the part of the article summarising my contribution to the conference, however, I should specify that the expression “salty Globigerina type” used to define the stone composing the masonry of the chapel is not exact. What I explained during the conference is that the deterioration of the painting is caused by large amounts of soluble salts, and that the type of Globigerina limestone used for the masonry is particularly prone to salt decay. I find that ‘salty Globigerina type’ gives the impression that the stone used already contained salts when quarried, and this is not the case for the masonry of the dome of the chapel of the Crucifix.

This letter also gives me the opportunity to comment on another article published in The Malta Independent of 17 April, which made a similar erroneous statement. The article by Bernard Busuttil was entitled “Centuries-old institutes work together in Cospicua” and dealt with the restoration project of the same painting. In this article the high salt content of the stone is considered either as a consequence of sea spray or, according to Dr Simon Mercieca, because “the stone was already salty when quarried” – a statement he substantiated by saying that the quarry from which the stone was taken was located near the sea.

The results of the extensive scientific study I carried out for my M.Phil. on stone samples taken from the dome of the chapel showed that deterioration is caused by the presence of very large amounts of salts, namely sulphates, and in particular gypsum. The origin of this type of salt is usually associated with pollution and/or constituent materials (e.g. restoration materials).

The analyses also identified other types of salts, in particular chlorides, which originate from marine environments, but in very little amounts when compared to sulphates.

Deterioration of Cali’s painting in the chapel of the Crucifix, therefore, is being caused by large amounts of sulphates, which, at least in the large quantities identified in the samples collected, cannot possibly have a marine origin. They were not part of the stone when this was quarried but were introduced as a consequence of anthropic activities (e.g. pollution, restoration works, and so on.).

The oil painting by Calì in the chapel of the Crucifix has had an amazing troubled history, and bears evidence of serious past and present deterioration. It therefore deserves due attention, funds and an extremely carefully planned conservation strategy carried out by specialised professionals.

Roberta de Angelis