Table 1 List of statues analyzed and history of their treatments
Statue | Bronze-like patina | Physical/ mechanical | Chemical | Molding |
|---|---|---|---|---|
Madonna della Rosa attributed to Simone di Ferrucci 1399 | No | Dusting with brushes. | Poultices with anion-exchange resins. Cotton swabs with turpentine in areas with gilding. Final coating with microcrystalline wax. | Fluoroelastomer Akeogard CO 10% in acetone (protective barrier), microcrystalline wax (detaching material), silicone rubber to take the mold. Gilding areas protected with microcrystalline wax. |
S. Eligio by Nanni di Banco ca.1417-1421 | Yes | Air-abrasive with aluminum oxide powder. | Unknown (old treatment) | |
San Giacomo Maggiore by Niccolò di Pietro Lamberti ca. 1414 | Yes | Air-abrasive with aluminum oxide powder. | Sepiolite poultice with ammonium carbonate in some areas. On the back, poultice with distilled water. | As for Madonna della Rosa |
San Filppo by Nanni di Banco 1410 | Yes | Air-abrasive with aluminum oxide powder. Gilded areas: Laser Nd:YAG (1064 nm) and Nd:YAP (1340 nm). | As for Madonna della Rosa | |
Quattro Santi Coronati by Nanni di Banco ca.1409 – 1417 (group of four statues) | Yes | Final cleaning of non-gilded areas with rotating siliconic device. Gilded areas: Laser Nd:YAG (1064 nm) and Nd:YAP (1340 nm). | Poultice with 7% aqueous EDTA (slightly alkaline pH, 40 min-24 hrs). Deionized water. | As for Madonna della Rosa |
San Pietro attributed to Filippo Brunelleschi ca. 1421 | Yes | Air-abrasive with aluminum oxide powder. | As for Madonna della Rosa | |
San Marco by Donatello ca. 1413 | Yes | Air-abrasive with aluminum oxide powder. | Sepiolite poultice with ammonium carbonate in some areas. On the back, poultice with distilled water. Gilded areas: silica gels with sodium carbonate, poultice with ammonium carbonate. Consolidation with methyl organo-silicone resin (Rhodorsil 4673) in limited areas. | As for Madonna della Rosa |