THE ANGELS MUSICIANS OF THE CATHEDRAL
Another magnificent treasure from Gorizia. The frescoes in the Chapel of Sant'Acazio, which surround the four Evangelists in one of the few medieval fragments that Gorizia preserves, probably date back to the second half of the 15th century. This pictorial cycle of great impact, as you will see from the images, is a sign of joy and serenity, a roof, a sky, another treasure of Gorizia recently restored to its ancient splendour in the framework of the wider restoration of the Metropolitan Cathedral, which presents itself as a real mine of evidence of the oldest Gorizia. The little church of San'Acazio is incorporated in the Cathedral and the angels play the lute, a portable organ, a German psalter with sticks, a dulciana, an Alemannic flute, a harp, a drum and a strange mandola very smiley to a guitar (perhaps modified in the restoration that such Melicher performed in 1904 and already then much criticized. Those same instruments on which the elegant music room in the castle was built in 1996-98, prodromal to that Thetarum Instrumentorum which we later made together with Paolo Cecere, Fabio Cavalli at the Insieme Dramsam and the Accademia Jaufré Rudel. Today that exhibition is among the most appreciated of those who visit the castle and our city. Everything starts anyway from those extraordinary angels musicians, from that angelic roof above Gorizia.
The restoration of the frescoes on the vault of the Chapel of Sant'Acazio began on 12 February 2010 with the conferral of the task by the Regional Directorate for Cultural and Landscape Heritage of Friuli Venezia Giulia. The frescoes, painted in the late Gothic period between the 14th and 15th centuries, depict the symbols of the Evangelists at the centre and sixteen angels on the segments, with musical instruments of Nordic tradition, presumably of Carinthian descent. The work was preceded by a campaign of stratigraphic investigations carried out on the plastered parts of the chapel, and on the ribs of the vault, to find any hidden late Gothic fresco decorations or finishes. A pre-World War I photograph documents the presence of an Annunciation on the wall leading to the right side aisle of the Duomo. No trace of these frescoes, presumably coeval with those of the vault, has remained. The entire Duomo was the object of an extraordinary maintenance intervention that involved - to reconcile the various works planned in the yard - some suspensions to the restoration work on the paintings of the Chapel of St. Acacius, which was completed in February 2015. The works were carried out under the direction of Dr Beatrice Di Colloredo Toppani, of the Superintendence for Historical, Artistic and Ethno-anthropological Heritage of Friuli Venezia Giulia and the Architect Lino Visintin appointed by the Archiepiscopal Curia of Gorizia.
At the time of the intervention, the frescoes were in a critical state of conservation. The surface was covered with a thick layer of dirt and black oily smoke. Previous infiltrations of rainwater had caused a runoff on the plumes, with loss of the paint film and the presence of saline efflorescence. The plasters also had macroscopic defects of adhesion, both in-depth and at the level of the plaster, the latter characterized by widespread cracking and lifting.
The first cleaning tests immediately revealed that the frescoes had undergone heavy repainting work, probably during the decoration of the adjacent vault which, in 1906, had been painted with 15th century hypomorphic motifs by Hans Viertelberger¹. It is assumed that on that occasion, to tune the 19th-century vault in neo-Gothic style, the original frescoes were repainted with the result of dramatically darkening the tones. The massive and extensive repainting work on the entire surface was also justified by the poor state of conservation of the late Gothic paintings, which emerged after cleaning with all their shortcomings and lacunae. The arbitrary interpretations made during the "recovery" phase of the original paintings had also contributed to making their reading more confusing. The data obtained from the chemical investigations carried out on six samples of frescoed plaster show, as the first data, that a large part of the paintings was made according to the canonical technique of fresco painting, with the pigments diluted in water and spread on the plaster still damp. All the samples analysed show a whitish plaster at the base obtained by mixing aerial lime with predominantly medium-fine sand and presumably with a mostly carbonate nature. As far as the pictorial layers are concerned, microscopic observation, together with instrumental analysis, has shown that they are mostly pigments spread on the plaster still fresh, with the latter providing, through the outcrop of calcium hydroxide, the calcium carbonate matrix that now binds the pigments. The pigments used for the restoration The pigments used are the classic ones, resistant to the basicity of lime, such as red and yellow ochres, with also purple pigments such as strongly hematic ochres, and carbon black. Of course, there are also layers laid dry, such as on the bottom of the symbol of the Evangelist Luke and the edge of the angel with the guitar - samples 3 and 4 - where the blue layers can be traced back to temperas based on azurite, white sangiovanni and, originally a protein glue now completely altered, but whose presence is originally evidenced by the discovery of calcium oxalate.
A special mention should be made of sample 6, taken from a rib, where the red layer has an inorganic composition similar to that of the other red layers, but possessing a rather high thickness, having underneath the classic veil of outcropped lime and carbonate, being quite distinct from the support and finally containing calcium oxalate, is traced back to a tempera paint or at most to lime added with glue to promote adhesion.
On all the samples and on the surface are found secondary gypsum deposits, presumably deriving from the alteration of the calcium carbonate constituting the plaster or present in the matrix of the pictorial layers. This statement is based on the fact that the paint layers constantly show very low thicknesses, demonstrating their partial decohesion. The latter is also evidenced by the discovery of ochre dust from the underlying paintings inside the gypsum deposits. Sometimes this presence is also abundant, so much so that the deposit is coloured in orange-yellow, for example on samples 1 and 2 (white and purple background of the Angel of St. Matthew, fig. 17), and 6 (rib).
It should be underlined that on the surface of samples 1 and 2 traces of calcium oxalate are found, which presumably is due to surface treatments based on glues (on the other samples its finding is to be put concerning the temperas mentioned above).
Finally, on the surface of samples 1, 2 and 4, traces of a modern synthetic resin of the acrylic type were found, presumably attributable either to old restorations (in any case from the second half of 1900) or to pre-consolidation of the frescoes.