Improvements in bones and stones consolidating processes by vacuum system method.

The degradation of materials commonly starts on the surface of the object and proceeds towards inside through pores, increasing fractures and lesions. To restore mechanical and aesthetic characteristics, it is necessary by the application of consolidants to fill these weak points so that they become inaccessible to corrosive agents. Greater is the amount of consolidant that penetrates, greater the efficiency of the restoration. This is the limiting factor of many approaches which due to very tight pores result not fully successful. The consolidation under vacuum can help to pass these difficulties. So we have adopted it to restore Macco samples and tested to consolidate archaeological bones. The samples were consolidated by complete immersion under vacuum (-700 mm Hg), in a consolidant solution containing 8% w/V of diammonium phosphate. The success of the application to both the kind of samples is shown by microscope images, SEM-EDAX analysis, and weight variation.

Technical Note: Post-burial alteration of bones: Quantitative characterization with solid-state 1H MAS NMR.

The identification of markers of the modifications occurring in human bones after death and of the sedimentary and post-sedimentary processes affecting their state of preservation, is of interest for several scientific disciplines. A new index, obtained from spectral deconvolution of the 1H MAS NMR spectra of bones, relating the number of organic protons to the amount of hydrogen nuclei in the OH- groups of bioapatite, is proposed as indicator of the state of preservation of the organic fraction. In the osteological material from three different archaeological sites, this index resulted positively correlated with the extent of collagen loss derived from infrared spectroscopy. Its sensitivity to changes in the physical and chemical characteristics of bone allows to identify distinct diagenetic pathways specific to each site and to distinguish different trajectories within the same site.

A new miniaturised short-wave infrared (SWIR) spectrometer for on-site cultural heritage investigations.

The paper reports on the development of an analytical method based on the use of a new miniaturised short-wave infrared (SWIR) spectrometer for the analysis of cultural heritage samples. The spectrometer is a prototype characterised by small dimension (45.0 mm in diameter x 47.5 mm in height x 60 g weight), easily handled and transferable out of research laboratories. The prototype enables the acquisition of spectra in the SWIR range of 1200-2200 nm, which is a unique feature for miniaturised spectrometers. The exploitation of this spectral range allows the detection of a high number of combination and overtone bands, which guarantees significant diagnostic power to the instrument. The present study lays a significant foundation to the development of analytical strategies based on miniaturised NIR spectrometers working in the SWIR spectral range for the characterization of complex samples such as cultural heritage specimens. Analytical performances of the new spectrometer were assessed on archaeological bones, cinematographic films and bronze patinas. The selected cases of study present challenging conservation issues not properly addressed, and their analyses usually require to be performed on-site, in places not easily accessible by restorers, archaeologists and/or scientists. The data acquired with the prototype, combined with a multivariate data analysis approach, show the possibility to i) differentiate between the materials used as a support for cinematographic film namely cellulose nitrate (CN), cellulose acetates (CA) and polyethylene terephthalate (PET); ii) sort out archaeological bone fragments according to their collagen content as an initial screening test for bones characterization; iii) differentiate between corrosion products on outdoor bronze sculpture, which is important for assessing the state of conservation of the artwork. The prototype enabled rapid information acquisition to guide restoration strategies, which need to be supported in real time by quick and easy analytical procedures.

Isolation and Analysis of Proteoglycans and Glycosaminoglycans from Archaeological Bones and Teeth.

We have developed methods for isolating proteoglycans and glycosaminoglycans from archaeological bones and teeth. These methods have been previously published (Coulson- Thomas et al., 2015 ) and are described here in more detail. In the case of glycosaminoglycans, the method was a previously described method ( Nader et al., 1999 ) which we optimized for archeological samples.