Restoration of cultural heritage: evaluation of the compatibility between metals and sealing products

When restoring historical monuments, it is often verified that reinforcements, mostly made of ferrous alloys, are in quite a bad state and must be partially or totally replaced to prevent further degradation or accidents. Modern alloys such as stainless steels are increasingly used for such purpose, which raises the open question concerning their compatibility with the new types of sealing products available on the market. Even though it is not possible to use accelerated tests to give a livelong guarantee of adequacy of materials combination, electrochemical tests of metals in an aqueous extract of the sealing products could be used as screening to rapidly identify situations that would conduce to the premature corrosion of the metal.     

Thermography data fusion and nonnegative matrix factorization for the evaluation of cultural heritage objects and buildings

Journal of Thermal Analysis and Calorimetry - The application of the thermal and infrared technology in different areas of research is considerably increasing. These applications involve...     

Large sample neutron activation analysis: a challenge in cultural heritage studies

Large sample neutron activation analysis compliments and significantly extends the analytical tools available for cultural heritage and authentication studies providing unique applications of non-destructive, multi-element analysis of materials that are too precious to damage for sampling purposes, representative sampling of heterogeneous materials or even analysis of whole objects. In this work, correction factors for neutron self-shielding, gamma-ray attenuation and volume distribution of the activity in large volume samples composed of iron and ceramic material were derived. Moreover, the effect of inhomogeneity on the accuracy of the technique was examined.     

Synthesis and protective properties of titanium nitride coatings on willemite

The instability of brightness and light output of a photoluminescent phosphor based on Mn²⁺-activated willemite (Zn₂SiO₄:Mn) were examined as influenced by the ultrafine titanium nitride layers synthesized based on a molecular layering technique. Using the technique of radical-recombination luminescence excited in a stream of hydrogen atoms, the spectral characteristics of the initial and of modified phosphors were determined.     

Micelle,microemulsions, and gels for the conservation of cultural heritage

Past restorations performed with acrylic and vinyl polymers showed detrimental effects to wall paintings that lead to the complete disfiguration of the painted surfaces. The removal of these materials performed with the traditional solvent-based methodology represents a real challenge to conservators and usually achieves very poor results. This review reports on the new palette, nowadays available to restorers, based on microemulsions, micellar systems, physical and chemical gels specifically formulated for the cleaning of cultural heritage artefacts. These systems have been developed in the last twenty years within the cultural framework of colloids and surface science.     

Development of a technique based on multi-spectral imaging for monitoring the conservation of cultural heritage objects

A new approach for monitoring the state of conservation of cultural heritage objects surfaces is being developed. The technique utilizes multi-spectral imaging, multivariate analysis and statistical process control theory for the automatic detection of a possible deterioration process, its localization and identification, and the wavelengths most sensitive to detecting this before the human eye can detect the damage or potential degradation changes occur. A series of virtual degradation analyses were performed on images of parchment in order to test the proposed algorithm in controlled conditions. The spectral image of a Dead Sea Scroll (DSS) parchment, IAA (Israel Antiquities Authority) inventory plate # 279, 4Q501 Apocryphal Lamentations B, taken during the 2008 Pilot of the DSS Digitization Project, was chosen for the simulation.     

On the application of electrochemical impedance spectroscopy to study the self-healing properties of protective coatings

Active corrosion protection based on self-healing of defects in coatings is a vital issue for development of new advanced corrosion protection systems. However, there is a significant lack of experimental protocols, which can be routinely used to reveal the self-healing ability and to study the active corrosion protection properties of organic and hybrid coatings.The present work demonstrates the possibility to use EIS (electrochemical impedance spectroscopy) for investigation of the self-healing properties of protective coatings applied on a metal surface. The model EIS experiments supported by SVET (scanning vibrating electrode technique) measurements show that an increase of low frequency impedance during immersion in the corrosive medium is related to the suppression of active corrosion processes and healing of the corroded areas. Thus, EIS can effectively be employed as a routine method to study the self-repair properties of different protective systems. The 2024 aluminium alloy coated with hybrid sol–gel film was used as a model system to study the healing of artificial defects by an organic inhibitor (8-hydroxyquinoline).     

The use of electrochemical impedance spectroscopy (EIS) in the evaluation of the electrochemical properties of a microbial fuel cell

Electrochemical impedance spectroscopy (EIS) has been used to determine several electrochemical properties of the anode and cathode of a mediator-less microbial fuel cell (MFC) under different operational conditions. These operational conditions included a system with and without the bacterial catalyst and EIS measurements at the open-circuit potential of the anode and the cathode or at an applied cell voltage. In all cases the impedance spectra followed a simple one-time-constant model (OTCM) in which the solution resistance is in series with a parallel combination of the polarization resistance and the electrode capacitance. Analysis of the impedance spectra showed that addition of Shewanella oneidensis MR-1 to a solution of buffer and lactate greatly increased the rate of the lactate oxidation at the anode under open-circuit conditions. The large decrease of open-circuit potential of the anode increased the cell voltage of the MFC and its power output. Measurements of impedance spectra for the MFC at different cell voltages resulted in determining the internal resistance (R(int)) of the MFC and it was found that R(int) is a function of cell voltage. Additionally, R(int) was equal to R(ext) at the cell voltage corresponding to maximum power, where R(ext) is the external resistance that must be applied across the circuit to obtain the maximum power output.     

Total reflection X-ray fluorescence and archaeometry: Application in the Argentinean cultural heritage

Archaeometry is an interdisciplinary research area involved in the development and use of scientific methods in order to answer questions concerned with the human history. In this way the knowledge of archaeological objects through advanced chemical and physical analyses permits a better preservation and conservation of the cultural heritage and also reveals materials and technologies used in the past. In this sense, analytical techniques play an important role in order to provide chemical information about cultural objects. Considering the non destructive characteristic of this study, analytical techniques must be adequate in order to prevent any alteration or damage and in addition to allow the conservation of their integrity. Taking into account the irreplaceable character of the archaeological and artistic materials considered in this study, analytical techniques must be adequate in order to prevent any alteration or damage and in addition to allow the conservation of their integrity.     

Applications of mass spectrometry in cultural heritage: identification of ligands employed for mordant gilding

Three different samples of gilding from wall paintings, from the Palazzo della Ragione in Padua, have been investigated by GC/MS analysis of their basic hydrolysis products obtained using trimethyl(alpha,alpha,alpha-trifluoro-m-tolyl)ammonium hydroxide (TMTFTH). The method employed allowed the identification of the mordant used for the paints, and consequently to distinguish Menabuoi's original painting from the others produced by extensive restorations. This was achieved by characterizing, among the hydrolysis products, molecular species characteristic of natural resins, siccative oils and waxes.     

Diagnostic Raman spectroscopy for the forensic detection of biomaterials and the preservation of cultural heritage

This paper reviews the contributions of analytical Raman spectroscopy to the non-destructive characterisation of biological materials of relevance to forensic science investigations, including the sourcing of resins and the identification of the biodegradation of art and archaeological artefacts. The advantages of Raman spectroscopy for non-destructive analysis are well-appreciated; however, the ability to record molecular information about organic and inorganic species present in a heterogeneous specimen at the same time, the insensitivity of the Raman scattering process to water and hydroxyl groups, which removes the necessity for sample desiccation, and the ease of illumination for samples of very small and very large sizes and unusual shapes are also apparent. Several examples are used to illustrate the application of Raman spectroscopic techniques to the characterisation of forensic biomaterials and for the preservation of cultural heritage through case studies in the following areas: wall-paintings and rock art, human and animal tissues and skeletal remains, fabrics, resins and ivories.     

Techniques of thermal analysis applied to the study of cultural heritage

It is increasingly important that chemistry reaches people who have not studied directly this field of science but that, daily, have practices where chemistry is involved in various extents. This is what happens, for instance, in the activities related with the study and the preservation of cultural heritage. In this sense, the present work is a short review of the particular case of techniques based on the thermal analysis and calorimetry applied within the context of the characterization of art and archeological objects, exemplified by various case studies, as the characterization of mortars, preparatory grounds, ancient painting materials and drying oils.     

Electrodeposition of Zn-Mn/CeO2 composite coatings: evaluation of corrosion properties

Journal of Solid State Electrochemistry - The aim of this paper is electrodeposition of Zn/CeO2 and Zn-Mn/CeO2 nanocomposite coatings. Four plating solutions were used (R1–R4). Solution R1...