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Featured Application: This research paper contributes to improving the central Italy Renaissance database on painting materials and techniques. After a huge non-invasive diagnostic campaign performed on the corpus of Giovanni Santi's artworks, three paintings were selected and investigated: the Martyrdom of Saint Sebastian panel, the Visitation altarpiece and the canvas with Tobias and the Archangel Raphael (c. 1487 and 1494). Micro-invasive investigations including optical microscopy, ESEM-EDX, micro-Raman spectroscopy, FTIR and FTIR-ATR spectroscopy and GC-MS were carried out on selected micro samples. The results of the integrated analyses confirmed the use of a Renaissance palette with oil and, only in a few cases, tempera techniques. Some significant peculiarities emerged in Santi's practice, as he used localized off-white priming and colorless powdered glass with a siccative oil—in red, flesh, pinkish and green hues—confirming the influence of the Flemish painters in Urbino and, possibly, also in western central Italy. This innovative technical expedient compared to the traditional Italian painting technique was identified also in red and bluish samples collected from the Communion of the Apostles panel painted by Justus of Ghent around 1473–1474 for Urbino Corpus Domini Confraternity. The Flemish master was called to the court of Duke Federico to paint in oil and his presence at the 'Urbino workshop' probably contributed to the diffusion of this technique. Both in Giovanni Santi's paintings and the Communion of the Apostles, the glass particles are related to a soda-lime glass typical of the Italian area, widely detected in Italian paintings from the late 15th and 16th centuries. [ABSTRACT FROM AUTHOR]

New highly hydrophobic fluorinated oligoamides were synthesized and studied as materials for the protection of non-varnishable wooden artifacts. The new oligoamides were designed to achieve the best performance (including high chemical affinity to the wood material) and the lowest environmental impact. In order to minimize the risk of bioaccumulation, short perfluoroalkyl side chains were reacted with oligoethylene L-tartaramide (ET), oligoethylene adipamide-L-tartaramide (ETA), oligoethylene succinamide-L-tartaramide (EST), oligoethylene succinamide (ES), and oligodiethylenetriamino-L-tartaramide (DT). Favorable reaction conditions were also adopted to obtain low molecular weight compounds characterized by non-film-forming properties and solubility or dispersibility in environmentally friendly organic solvents. Their behavior in terms of modification of the wood surface characteristics, such as wettability, moisture absorption, and color, was analyzed using a specific diagnostic protocol to rapidly obtain preliminary, but reliable, results for optimizing a future synthesis of new and tailored protectives. The influence of different monomer units on the reactivity, solubility, and hydrophobic properties of different oligoamides was compared showing ESF (contact angle 138.2°) and DF (132.2°) as the most effective products. The study of stability to photochemical degradation confirms ESF as promising protective agents for artefacts of historical and artistic interest in place of long-chain perfluoroalkyl substances (PFAS), products currently subject to restrictions on use. [ABSTRACT FROM AUTHOR]

Paintings on canvas are complex structures created by superimposing layers of different composition. Investigations on the structure of these artworks can provide essential information on their state of conservation, pictorial technique, possible overpaintings, and in planning a proper conservation plan. Standard methods of investigation consist in sampling a limited number of fragments for stratigraphic analyses. Despite the recognized validity of these methods, they are affected by evident limitations. Nuclear magnetic resonance (NMR) profiling, often named NMR stratigraphy, is an NMR relaxometry technique applied by single‐sided portable devices developed to overcome the disadvantages of microinvasive stratigraphic analyses. The potential of this approach on artworks, including wall paintings and a few examples of painted canvas, is described in the literature. In this study, NMR profiles of painting on canvas were examined by analyzing transverse relaxation time data by T2 quasi‐continuous distributions and the results compared with standard stratigraphic cross‐sections analysis. Combining signal intensity and T2 quasi‐continuous distributions, the identification of textile, preparatory, and paint layers was enhanced. The diction "NMR stratigraphy" for these inhomogeneous layered artworks is also discussed. Indeed, unlike the stratigraphic cross‐sections, NMR profiles provide information on a volume (flat slice), rather than on a surface, and the collected signal can derive from nonuniform and partially overlapping layers. This study paves the way for extensive investigations on relaxation time quasi‐continuous distributions in various binder/pigment mixtures in order to improve the reliability of NMR profile as an innovative, non–invasive, and nondestructive method for analyzing paintings on canvas. [ABSTRACT FROM AUTHOR]

Parameters related to pore-space structure of the trabeculae in cancellous bone are difficult to determine quantitatively, but they can be important to characterize changes induced in bone by diseases such as osteoporosis. We present two nuclear magnetic resonance (NMR) methods to measure the internal porosity φ[sub trab] of the trabeculae, based on two different measurements of the fraction of intratrabecular and intertrabecular pore-space in animal femur samples. These procedures have been developed within the more general framework of the NMR studies for fluids in porous media. In the first method we use the ratio between the amount of collagen (solid-like) [sup 1]H and that of the fluids in the samples. In the second, which can be applied only on defatted and water saturated samples, we use the distributions of longitudinal relaxation times. The φ[sub trab] values obtained are constant for porosity φ of the samples over the range 40%–70%, with each method giving φ[sub trab]=(29±4)%, which is consistent with the only data available, the porosity of related cortical bone. The traditional parameter bone volume fraction is simply given by (1-φ)/(1-φ[sub trab]). © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

As an effective conservation material for wall paintings, ancient paper, and stone artifacts, nano Ca(OH)2 has been studied for more than two decades. However, the synthesis methods are expensive, complex, time‐consuming, or require considerable energy. To tackle the issue, we report, in this study, a facile, large‐scale, time saving, and economical method for synthesizing nano Ca(OH)2 (∼90 nm) at room temperature. This is achieved by controlling crystal growth of Ca(OH)2 at the (1‾010) facet (vertical direction) and (0001) facet (horizontal direction) with simultaneous addition of octyl phenyl polyoxyethylene ether (OPPE) and dimethylformamide (DMF) in the reaction. Density functional theory (DFT) calculations revealed that the crystal dimensionality tuning is caused by attaching OPPE to the (0001) facet and DMF to the (1‾010) facet of Ca(OH)2. Experimental results showed that the synthesized nano Ca(OH)2 has higher stability and carbonation degree than commercial Ca(OH)2 and was used for consolidating a 1300‐year‐old tomb painting, which is a very important, precious, and heavily damaged national treasure of China. The results demonstrate that the nano Ca(OH)2 shows excellent penetration into the painting, considerably improves the strength of the painting, and has no side effects on the color, pore distribution, and porosity of the painting. Our work will significantly facilitate the industrial production of nano Ca(OH)2 and its application in cultural heritage conservation. [ABSTRACT FROM AUTHOR]

A portable hyperspectral sensor collects reflectance spectra in the 350-2500 nm range, allowing the identification of not only inorganic but also organic materials. In this paper, a non-invasive and non-destructive characterization of pictorial binders was used. The results show that their main spectral differences are located between 1200-2400 nm. It is also indicated that when a binder is mixed with colorants, some modifications occur in respect to its original spectrum. In addition, the first derivative transformation of original spectra allows an easier identification of these organic binders, where the most discriminating regions are 1160-1250 nm and 1660-1800 nm. [ABSTRACT FROM AUTHOR]

Scientists applying magnetic resonance techniques to cultural heritage are now a quite vast and international community, even if these applications are not yet well known outside this community. Not only laboratory experiments but also measurements in the field are now possible, with the use of portable nuclear magnetic resonance (NMR) instruments that enable non-invasive and non-destructive studies on items of any size, of high artistic and historical value as well as diagnosis of their conservation state. The situation was completely different in the second half of the 1990s when our group started working on applications of NMR to cultural heritage, by combining the knowledge of NMR for fluids in porous media at the University of Bologna, with the skilfulness of the chemists for cultural heritage of CNR and University of Florence, and Safeguarding Cultural Heritage Department of Aosta. Since then, our interest has been mainly devoted to develop methods to study the structure of pore space and their changes as a result of the decay, as well as to evaluate performance of the protective and conservative treatments of porous materials like stone, ceramic, cements and wood. In this paper, we will review the pathway that led us from the first tentative experiments, in the second half of the 1990s to the current work on these topics. [ABSTRACT FROM AUTHOR]

This article discusses a study on the modification of minoma tannin to produce leather with improved properties. The study used formaldehyde, urea, a sulfonic acid and a sulfiting agent in the modification. It revealed a higher molecular weight of the leather than mimosa tannin. It used physicochemical and technological tests to characterize modified tannis.

Abstract: Nuclear magnetic resonance (NMR) portable devices are now being used for nondestructive in situ analysis of water content, pore space structure and protective treatment performance in porous media in the field of cultural heritage. It is a standard procedure to invert T 1 and T 2 relaxation data of fully water-saturated samples to get “pore size” distributions, but the use of T 2 requires great caution. It is well known that dephasing effects due to water molecule diffusion in a magnetic field gradient can affect transverse relaxation data, even if the smallest experimentally available half echo time τ is used in Carr–Purcell–Meiboom–Gill experiments. When a portable single-sided NMR apparatus is used, large field gradients due to the instrument, at the scale of the sample, are thought to be the dominant dephasing cause. In this paper, T 1 and T 2 (at different τ values) distributions were measured in natural (Lecce stone) and artificial (brick samples coming from the Greek–Roman Theatre of Taormina) porous media of interest for cultural heritage by a standard laboratory instrument and a portable device. While T 1 distributions do not show any appreciable effect from inhomogeneous fields, T 2 distributions can show strong effects, and a procedure is presented based on the dependence of 1/T 2 on τ to separate pore-scale gradient effects from sample-scale gradient effects. Unexpectedly, the gradient at the pore scale can be, in some cases, strong enough to make negligible the effects of gradients at the sample scale of the single-sided device. [Copyright &y& Elsevier]

The restoration of paintings always involves the removal of darkened superficial layers, which are mainly due to dust deposition and aged varnishes. As cleaning is an irreversible and invasive treatment, physical methods (i.e., laser cleaning) instead of chemical ones are frequently suggested to reduce side effects on pictorial layers. Among the most employed laser systems, the free-running Er:YAG laser is considered very suitable for fine arts cleaning. This laser works at 2.94 μm, at which only –OH and –NH bonds in molecules are excited. This character can become a disadvantage when pigments with these functional groups are present. To understand the potential of the Er:YAG laser in such situations or in the presence of degradable pigments, the effectiveness of varnish removal from paintings prepared with egg yolk as the binder and cinnabar and lead white as the pigments were systematically investigated. Different cleaning conditions were used, and a hyperspectral sensor was innovatively used as a rapid, in situ and non-destructive technique to assess the effects of laser ablation, besides microscopic analysis. Though results obtained show all these pigments are sensitive to this laser radiation, satisfactory cleaning can be achieved without damaging the pictorial layer. The best cleaning conditions were 0.5 W of power (50 mJ and 10 Hz for energy and frequency), with 2-propanol as the wetting agent. [ABSTRACT FROM AUTHOR]

The protection of stone cultural assets is related to the transformation of the surface characteristic from hydrophilic to hydrophobic/superhydrophobic through the application of a coating. The suitability of a coating depends not only on its capability to dramatically change the surface wettability, but also on other parameters such as the modification of kinetics of water absorption, the permanence of vapor diffusivity, the resistance of the coating to aging and the low volatile organic compound emissions during its application. In this work, an oligo(ethylensuccinamide) containing low molecular pendant perfluoropolyether segments (SC2-PFPE) and soluble in environmentally friendly solvents was tested as a protective agent for historic stone artifacts. Magnetic resonance imaging and relaxometry were employed to evaluate the effects of the surface wettability change, to follow the water diffusion inside the rock and to study the porous structure evolution after the application of SC2-PFPE. A sun-like irradiation test was used to investigate the photo-stability of the product. The results demonstrate that the highly photo-stable SC2-PFPE minimizes the surface wettability of the stone by modifying the water sorptivity without significantly affecting its porous structure and vapor diffusivity. The improved performance of SC2-PFPE in comparison to other traditional coatings makes it a potential candidate as an advanced coating for stone cultural heritage protection. [ABSTRACT FROM AUTHOR]

Tetraethyl orthosilicate (TEOS) is extensively used in the conservation of stone-built cultural heritage, which is often subjected to water-induced degradation processes. The goal of this study was to produce and study a TEOS-based material with the ability to repel liquid water. A sol solution of TEOS and 1H,1H,2H,2H-perfluorooctyl triethoxysilane (FAS) was prepared and deposited on marble. The static contact angles (CAs) of water drops on the coated marble surface were >170° and the sliding angles (SA) were <5°, suggesting that superhydrophobicity and water repellency were achieved on the surface of the synthesized TEOS-based coating. FTIR and SEM-EDS were employed to characterize the produced coating. The latter offered good protection against water penetration by capillarity, reducing the breathability of marble only by a small extent and with practically no effect on its aesthetic appearance. The durability of the coating was evaluated through various tests that provided very promising results. Finally, the versatility of the method was demonstrated as the TEOS-based coating was successfully deposited onto glass, brass, wood, silicon, paper and silk, which obtained extreme wetting properties. [ABSTRACT FROM AUTHOR]

The development of innovative materials is one of the most important focus areas in heritage conservation research. Eligible materials can not only protect the physical and chemical integrity of artworks but also preserve their artistic and aesthetic features. Recently, as one of the hot research topics in materials science, biomimetic superhydrophobic materials have gradually attracted the attention of conservation scientists due to their unique properties. In fact, ultra-repellent materials are particularly suitable for hydrophobization treatments on outdoor artworks. Owing to their excellent hydrophobicity, superhydrophobic materials can effectively prevent the absorption and penetration of liquid water as well as the condensation of water vapor, thus greatly relieving water-induced decay phenomena. Moreover, in the presence of liquid water, the superhydrophobic surfaces equipped with a self-cleaning property can clean the dirt and dust deposited spontaneously, thereby restoring the artistic features simultaneously. In the present paper, besides the basic principles of wetting on solid surfaces, materials, and methods reported for preparing bioinspired ultra-repellent materials, the recently proposed materials for art conservation are also introduced and critically reviewed, along with a discussion on the droplet impact and durability of the artificial superhydrophobic surfaces. Lastly, the current status and the problems encountered in practical application are also pointed out, and the focus of future research is presented as well. [ABSTRACT FROM AUTHOR]

Preserving ancient wall paintings from damage has become a challenge over the years. Nanosized calcium hydroxide (Ca(OH) 2 ) has been identified as a promising material to preserve wall paintings. However, the synthesis of nanosized Ca(OH) 2 is extremely difficult. Here, we demonstrate a breakthrough in wall painting protection enabled by boron nitride nanosheets (BNNSs) through strategic synthesis Ca(OH) 2 -BNNS nanohybrids using an aqueous method. The BNNS have two significant functionalities in the design and implementation of the Ca(OH) 2 nanomaterials. First, the introduction of BNNS results in the successful synthesis of uniform and nanosized Ca(OH) 2 (∼80 nm) in the nanohybrids, which can be attributed to the supersaturation-induced "etching-stripping" mechanism. More interestingly and importantly, a unique gradient penetration structure is strategically formed when applying Ca(OH) 2 -BNNS hybrids on the wall paintings, i.e., the BNNS-rich layer will be at the surface of wall painting, whereas Ca(OH) 2 nanomaterials prefer to penetrate deep in to the wall paintings. This gradient structure will allow the BNNS-rich layer to protect the wall paintings from fire, which is the first report to date among the protection materials for wall paintings; at the same time, nanosized Ca(OH) 2 shows superior wall painting consolidation strength compared to commercial Ca(OH) 2 material. These results endow new applications of the newly emerging two-dimensional nanomaterials for protecting cultural heritage.

The changes in the surface wettability of many materials are receiving increased attention in recent years. It is not too hard to fabricate resistant hydrophobic surfaces through products bearing both hydrophobic and reactive hydrophilic end groups. More challenging is obtaining resistant nonwetting surfaces through noncovalent reversible bonds. In this work, a fluorinated oligo(ethylenesuccinamide), soluble in solvent benign for operators and environment, has been synthesized. It contains two opposite functional groups (perfluoropolyether segments and amidic groups) (SC2-PFPE) that provide water repellency while hydrophilicity is retained. Its performance has been tested on porous calcarenite and investigated by magnetic resonance imaging, water capillary absorption, and vapor diffusivity tests. The results demonstrate that SC2-PFPE modifies the wettability of porous substrates in a drastic and durable way and reduces the vapor condensation inside the pore space due to the perfluoropolyether segments that act at the air/surface interface.