For over a century, Giuseppe Calì’s mural The Triumph of the Immaculate Conception has adorned the parish church of Sacro Cuor (Sacred Heart) in Sliema.

The iconic 19th-century oil-on-stone painting blends artistic mastery with deep religious symbolism, however, time has taken its toll and now it is set for it to undergo an extensive conservation and restoration project to ensure its preservation for future generations.

The official launch of the restoration project will take place on February 24, marking the beginning of a detailed and carefully planned conservation effort. 

This initiative is being led by PrevArti Co. Ltd, under the direction of conservator Pierre Bugeja, whose expertise in mural and fine art conservation will guide the delicate work required to stabilise and rejuvenate this important piece of Maltese heritage.

Need for conservation

Calì (1846–1930) is widely recognised as one of Malta’s most important artists. His work is displayed in churches and institutions across the islands, and The Triumph of the Immaculate Conception, painted in 1892, is a prime example of his ecclesiastical artistry.

The mural, positioned in the apsidal cap of the church’s choir, depicts the Virgin Mary standing on a crescent moon, surrounded by a choir of angels, pope Leo XIII, and St Francis, among other religious figures.

Details of the painting

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The composition is structured in a V-shape, directing the viewer’s focus towards the central figure of Mary.

Despite its enduring presence, the painting has suffered significant deterioration over the years due to environmental exposure, structural movement and ageing materials.

Restoration challenges

Like many historical church paintings, The Triumph of the Immaculate Conception has been affected by a variety of issues that necessitate careful intervention.

The painting currently has:

• Cracks and flaking paint: structural shifts in the church have caused visible cracks, particularly along the junctions between stone slabs, leading to paint detachment in some areas.

• Water damage and salt crystallisation: exposure to moisture and humidity has caused staining and salt deposits, which weaken the paint’s adhesion to the stone surface.

• Surface dirt and past restorations: layers of grime and past restoration materials have built up over time, affecting the artwork’s clarity and colour vibrancy.

If left untreated, these issues could lead to further damage, obscuring the details and artistic integrity of Calì’s original work.

Restoration process: what lies ahead

The project will follow international conservation standards (E.C.C.O.) and will be conducted in several key phases, ensuring that every step is scientifically informed and minimally invasive.

Phase 1: Documentation and research: Before any physical work begins, the restoration team will conduct extensive documentation of the mural, including high-resolution digital imaging to record the current condition, and material analysis to identify the original pigments, past interventions and the causes of deterioration. This will be accompanied by historical research to ensure that any conservation work aligns with Calì’s original artistic techniques.

Phase 2: Cleaning and surface stabilisation: One of the most delicate steps will involve the careful removal of surface dirt, crystallised salts, and aged varnish layers. Special conservation solvents and poultices will be used to lift unwanted residues without damaging the fragile paint beneath. Where paint detachment is occurring, a stabilisation process will be applied to secure the flaking areas and prevent further loss.

Phase 3: Structural repairs: The cracks and weakened junctions in the stone surface will be addressed through filling and consolidating cracks with conservation-grade materials, ensuring that repairs do not disrupt the original structure. The team will also be reinforcing vulnerable areas to prevent further shifting, stabilising the surface beneath the painting.

Another detail of the mural.

Phase 4: Inpainting and aesthetic integration: Where small portions of paint have been lost, reversible inpainting techniques will be used to restore the artwork’s visual coherence. This includes using the tratteggio method, where fine parallel strokes recreate missing areas while remaining distinguishable upon close inspection. The conservation process will be ensuring that colour matching aligns with Calì’s original palette, maintaining the painting’s stylistic authenticity.

Phase 5: Protective coating and final report: The final stage will involve applying a thin protective layer to guard against moisture, pollutants, and UV exposure, ensuring long-term preservation. A detailed conservation report will be compiled, documenting the original condition of the painting before restoration, the scientific findings and methods used during conservation as well as the final stabilised and restored artwork, ensuring full transparency of the process.

A cultural milestone for Sliema

The launch of the restoration project marks an important moment for Sacro Cuor parish church and the broader Sliema community. Beyond religious significance, this mural holds artistic and historical value, offering insight into 19th-century Maltese painting traditions and ecclesiastical iconography.

As the conservation work begins, it will serve as an opportunity for art historians, conservators  and the public to gain a deeper appreciation for the craftsmanship behind Malta’s sacred art.

The restoration launch: a celebration of heritage

The official launch of the restoration project will take place on February 24, as part of Bank of Valletta’s final Customer Outreach Event in Sliema.

The event will also feature a mini concert by the Malta Philharmonic Orchestra String Quartet, offering a fitting tribute to the fusion of music, history, and cultural preservation. It will be open to the public, free of charge.

This project marks the beginning of a long but necessary process to protect and restore a key piece of Malta’s artistic heritage.

Once complete, The Triumph of the Immaculate Conception will once again be able to be fully appreciated in its original form, continuing to inspire worshippers, visitors and art enthusiasts for years to come.