JUNE 2026
Monthly Progress Summary
OVERVIEW
Operations continued throughout June without notable interruption. Conservation work advanced on the vault, staircases, marble and altar mosaic, while archaeological investigations on 12-13 June examined selected floor areas and recorded evidence relevant to the historical development of the Grotto.
KEY PROGRESS
- Documented selected floor openings and the underlying cave surface, generating new hypotheses concerning early staircase geometry, the apsidal block, vault construction and floor chronology.
- Continued vault cleaning and salt extraction, removed or protected metal elements, filled compatible plaster losses, injected detached layers and selected a casein-lime chromatic treatment after trials.
- Selected a compatible NHL 3.5 lime pointing mortar using washed local aggregates and cocciopesto, and continued evaluation of Nano Estel for superficial stone consolidation.
- Advanced marble cleaning to more than 80% of the wall-cladding area using a controlled acetone and isopropyl-alcohol mixture.
- Cleaned the apse mosaic to reveal the Nativity composition and preparatory drawing, reinforced vulnerable edges and secured loose tesserae; an integration trial awaited approval.
IN BRIEF: Vault cleaning and grouting were substantially complete, marble cleaning exceeded 80%, and mosaic work was advanced. Thermal imaging of the vault was scheduled for 10 July.
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