Nanocontainer aqueous systems for removing polymeric materials from marble surfaces: A new and promising tool in cultural heritage conservation

The present study dealt with the characterisation of marble surfaces coated by three kinds of polymeric material usually employed in stones conservation and with the evaluation of the removal of these coatings from the surfaces by means of new nanocontainer aqueous systems constituted of micellar solutions (MS) and oil-in-water microemulsions (MC). The polymeric coatings were also subjected to accelerated artificial ageing in order to detect possible effects associated to natural photochemical ageing. The aim of the work was the assessment of the performance of such nanocontainer aqueous systems taking acetone (Ac) as a reference “traditional” solvent for the removal procedure. The characterisation was carried out by means of Scanning Electron Microscopy (SEM) and Environmental Scanning Electron Microscopy (ESEM), Fourier Transform Infra-Red (FTIR) and Nuclear Magnetic Resonance (NMR) spectroscopies and the results obtained showed that the performance of these innovative methods based on nanocontainer aqueous systems can be considered highly promising in the view of a “green approach” to the conservation of cultural heritage.     

The history of the “Virgin with Child” sculpture (Ottaviano,Naples, southern Italy): Hypotheses from archaeometric multi-technique investigations

A life-size whitish marble statue of a “Virgin with Child” has been recently rediscovered in the St. Rosario church located in Ottaviano, a small town near Naples (southern Italy). This artwork shows stylistic features of the Tuscan-Roman school of the 16th century, and is framed in an intriguing historical context. Historical documents testify that the sculpture was a property of the cadet branch of noble Tuscan family of the Medici, the Medici of Ottaviano. A multianalytical approach has been used to try to indicate the supply area of the white marble of the studied sculpture. Considering the whole mineralogical, petrographic and geochemical data, the source rock can be possibly limited to the main classical white marbles of the Mediterranean district, as the classical marble of Aphrodisias. A reuse practice of a former artwork can be also hypothesized.     

Ultrasonic phased array technology for the non-destructive testing of marble sculptures

The medical ultrasonic phased array technology was modified for the non-destructive testing of marble sculptures and the feasibility of the approach was evaluated. For this purpose, 1?MHz, 64-channel phased array electronic and phased array transducers were developed. The specifications of the electronics and the transducers are presented and discussed. Ultrasound images of inner structures of a marble sculpture are presented. The problem of the acoustic matching layers for different states of deterioration is discussed and the developments in view of a suitable matching layer solution are presented. This matching layer is combined with a new coupling technique that protects the marble surface. The results of experiments on ultrasound phantoms and on a marble sculpture are presented.     

Enzymatic decolorization of bacterial pigments from culturally significant marble

Marble monuments and facades are susceptible to microbial colonization. Microbial growth on a marble surface can develop into unsightly red stains whose removal has proven problematic. The purpose of this study was to determine if the red-brown stains on Isamu Noguchi's marble sculpture Slide Mantra (1991) could be caused by pigment-producing microorganisms and to assess the potential of enzymatic stain remediation. Traditional cell culture methods were used to isolate a pigmented bacterium from a stained area of the sculpture. Sequencing and analysis of the 16S rRNA gene identified the organism as a strain of Serratia marcescens, and FT-IR spectroscopy demonstrated that the pigment produced by the bacteria was most likely a prodigiosin. Decolorization of the pigment in solution demonstrated that the enzyme laccase from the fungus Trametes versicolor has potential as a decolorizing agent. This study suggests that enzymatic decolorization may be applicable to stains on culturally significant marble caused by microbial colonization.