Monthly Summary July 2026

OVERVIEW

In July, conservation progressed simultaneously on the Grotto's internal surfaces and on the external walls of the north and south entrances. The apse mosaic approached completion, work on stair masonry and marble continued, entrance restoration began, and structural, thermographic and indoor-air investigations were carried out.

KEY PROGRESS

• Completed final cleaning and compatible lime-mortar pointing of staircase stonework, removed unsuitable cement and selected corroded metal elements, and monitored Nano Estel consolidation trials.
• Continued cleaning the internal marble cladding and removing unsuitable joint mortar, with stabilisation of detached or cracked slabs identified for the next phase.
• Refined mosaic cleaning, removed earlier gypsum filler, injected detached preparatory layers, re-bedded mobile tesserae and filled losses; details of the Virgin, Child, ox, ass and angelic procession became clearer.
• Developed a selective cleaning method for the south-entrance mural paintings and began deep consolidation and filling before planned watercolour reintegration.
• Catalogued and dismantled unstable north-entrance marble slabs, cleaned their reverse faces, installed carbon-fibre dowels, reinstalled the slabs and coordinated concealed electrical conduits.

IN BRIEF: The apse mosaic was nearing completion and both entrances showed good progress. Next priorities were approval of final reintegration and protective treatments, marble stabilisation and completion of the entrance works.