A REMARKABLE RESTORATION

The monumental task of restoring the resting place of 12 Grand Masters of the Order of the Knights of St John has ensured its preservation for many more centuries.

he Grand Masters’ Crypt was built beneath the high altar of St John’s Co-Cathedral when the church was constructed in the late 16th century and contains the remains of the first 12 Grand Masters who headed the Order between 1522 and 1623. Its location made conditions disastrous for the frescos, monuments and stone sarcophagus. Extensive studies and research diagnosed fluctuating temperature and humidity, level, leaking water, salt and the build up of layers of dirt as the main causes of the extensive damage to this historic and revered building. Frescoes discoloured and became gradually detached from walls and the ceiling. The stone sarcophagi were damaged from powdering caused by rising damp and fluctuation in temperature and humidity levels.

THE WORK IN PROCCESS

Assessing the climatic and humidity conditions in the crypt, and an extensive period of monitoring the internal and external environment to understand how the immediate surrounding areas affected conditions in the crypt was carried out first. Trials were made on materials to be used to consolidate weak plaster areas, remove salt, consolidate the stone sarcophagi and clean the marble and bronze tombstones.

Layers of dirt were painstakingly loosened with brushes, then vacuumed up. The monuments were lightly cleaned with deionized water, with a variety of application methods including swabs and natural sponge.

The multiple layers of paint on the altar and its surrounding columns were flaking. In the light of analytical and archival evidence, the upper (modern) layers of paint on the altar and columns were removed and the lowest, potentially original layers, were kept, where possible. Occasionally, black fungi remained deeply embedded within the structure of the stone. As it could not be removed without damaging the original stone it was treated with a low concentration of biocide.

The monuments, being mainly composed of Globigerina limestone for the body, with marble or metal commemorative plaques and effigies, exhibited different degrees of deterioration according to stone type and location in the Crypt.

Great care was taken to discover and use restoration materials which are compatible with the original components, as this is essential for the consolidation and conservation these particular historic monuments.

RESTORATION OF THE ALTAR AND CRUCIFIXION GROUP

The Crucifixion group above the altar of the Grand Masters' Crypt is composedof six wooden statues representing Jesus, theVirgin Mary, Mary Magdalene, St John the Evangelist and two angels. The back ground of the Golgotha scene is clad in black Portaro marble slabs and is framed by a cornice made in Gia/lodiSiena marble, which was first cleaned of dust and residues of salts.

The statues were cleaned of deposits of dust and grime. Studies show that the group was over painted between the 18th and 19th centuries by applying layers of white oil-based paint and a coating of mixture of gypsum. The over painting was removed by application of solvent gels and the original finishing was restored.

The statues and the marble were in a poor state of conservation, as was the wood. The analysis of deterioration of the marble was carried out to identify the compositional materials to be used and to plan the methods of restoration accordingly.

LEGACY

The long-term survival of the Crypt and mitigation of damage depends on the permanent control of the environment. An environmental control system, consisting of a custom-made unit which includes heating and cooling, dehumidification and humidification is now in use.

The ambient conditions achieved and maintained by this equipment must remain constant. For this reason, a specifically designed glass door, that is hermetically sealed, has been installed to isolate the interior and sustain the delicate environment. The door was designed to incorporate a viewing platform allowing visitors to see the Crypt from outside and enjoy its historic relevance and artistic significance.

The Grand Masters’ Crypt is

Photo Credit: The St John’s Co-Cathedral Foundation