Fourier transform infrared (FTIR) spectroscopy is one of the most widely applied techniques for the investigation of cultural heritage materials. FTIR microscopy is well established as an essential tool in the microdestructive analysis of small samples, and the recent introduction of mapping and imaging equipment allows the collection of a large number of FTIR spectra on a surface, providing a distribution map of identified compounds. In this Account, we report recent advances in FTIR spectroscopy and microscopy in our research group. Our laboratory develops, tests, and refines new and less-studied IR spectroscopy and microscopy methods, with the goal of their adoption as routine analytical techniques in conservation laboratories. We discuss (i) the analysis of inorganic materials inactive in the mid-IR region by means of far-IR spectroscopy, (ii) the development of new methods for preparing cross sections, (iii) the characterization and spatial location of thin layers and small particles, and (iv) the evaluation of protective treatments. FTIR spectroscopy and microscopy have been mostly used in the mid-IR region of 4000-600 cm(-1). Some inorganic pigments, however, are inactive in this region, so other spectroscopic techniques have been applied, such as Raman spectroscopy. We suggest an alternative: harnessing the far-IR (600-50 cm(-1)). Our initial results show that far-IR spectroscopy is exceptionally useful with mural paintings or with corrosion products from which larger sample quantities can generally be collected. Moreover, the inorganic composition of a sample can be characterized by the presence of several compounds that are inactive in the mid-IR range (such as sulfides, oxides, and so forth). Stratigraphical analyses by FTIR microscopy can be hindered by the process of cross section preparation, which often involves an embedding organic polymer penetrating the sample's porous structure. Here, the polymer bands may completely cover the bands of organic compounds in the sample. However, a correct methodological approach can prevent such limitations. For example, it is always advisable to analyze the sample surface before preparing the cross section in order to characterize the preparation layers and the varnish layers, which are generally applied to the surface of a painting both to protect it and improve the color saturation. Furthermore, the innovative use of IR-transparent salts as embedding material for cross sections can prevent contamination of the embedding resin and improve detection of organic substances. Another key point in the use of FTIR microscopy in artwork analysis is spatial resolution. The high-energy output of a new integrated FTIR microscope enhances the ability to characterize and spatially locate small particles and thin layers. Moreover, the new configuration proves extremely useful in the evaluation of protective treatments, because larger areas may be analyzed in less time in comparison to traditional systems, allowing the collection of more statistical data.

Different Fourier transform infrared microspectroscopic techniques, using attenuated total reflection (ATR) mode and single-element mercury-cadmium-telluride (MCT) detector (mapping) or multielement MCT detector (raster scanning), are compared with each other for the characterisation of inorganic compounds and organic substances in paint cross sections. All measurements have been performed on paint cross sections embedded in potassium bromide, a transparent salt in the mid-infrared region, in order to better identify the organic materials without the interference of the usual embedding resin. The limitations and advantages of the different techniques are presented in terms of spatial resolution, data quality and chemical information achieved. For all techniques, the chemical information obtained is found to be nearly identical. However, ATR mapping performed with a recently developed instrumentation shows the best results in terms of spectral quality and spatial resolution. In fact, thin organic layers (approximately 10 microm) have been not only identified but also accurately located. This paper also highlights the recent introduction of multielement detectors, which may represent a good compromise between mapping and imaging systems.

Organo-and hydrogels have been proposed in the restoration field to treat different types of surfaces. The possibility to retain solvents and to have a controlled and superficial action allowed to use these materials for the removal of very thin layers applied on ancient historical objects, when the under paint layers are particularly delicate and water sensitive. In the last years, an increased attention has been devoted to the proposal of more healthy products to guarantee the safeguard of the operators. Few attention has been devoted to the development of green methods which foresee the use of renewable and biodegradable materials. The aim of this paper is to test a green organo-gel for the cleaning of water sensitive surfaces like varnished egg tempera paintings. The gel has been tested experimented on mock ups varnished with natural and synthetic materials and has been validated on a small portion of a Cimabue painting for the removal of two varnishes applied on two different test areas of the painting.

The purpose of the present research was to compare the effect of different embedding and polishing procedures on the performances achievable with Fourier Transformed Infrared (FTIR) microscopy in Attenuated Total Reflection (ATR) mode. The attention was specifically focused on this technique since it is generally considered one of the most appropriate methods to analyze cross sections, thanks to the fact that the recorded spectra are similar to those collected in transmission mode. The research work was structured as a round robin among six different conservation and research laboratories. They were asked to embed fragments derived from the same area of a real sample following each one a different procedure. The performances of FTIR microscopy in ATR mode were evaluated on the different cross sections, considering the cross section morphology and the possible source of contamination. The cross sections were previously observed with optical microscopy, Environmental Scanning Electron Microscope (ESEM) and confocal microscopy. Three procedures were eventually selected, because they provided the best results in terms of both limiting the contamination of the embedding medium and achieving good contact with the ATR crystal. They were: a) embedding in KBr; b) cyclododecane pre-treatment before embedding in an organic resin and cutting of the sample; c) embedding in an organic resin and polishing with argon ion milling. These three procedures were finally compared and the weak points outlined, indicating where improvements could be made for further researches.

Fully biodegradable novel bio‐based organogels were developed for removing aged protective films from the surfaces of paintings, aiming at providing effective cleaning tools, easily controllable by reducing the solvent permeation into underlying paint layers and not dangerous for human health and the environment. The gels were based on poly‐3‐hydroxybutyrate (PHB) as gelling agent, γ‐valerolactone (GVL) as solvent and triethyl citrate (TEC) as plasticizer. PHB‐gels were able to completely remove protective varnishes on real oil paintings, without affecting the pictorial layer and leaving negligible residues after the application. Moreover, the gels showed good mechanical and handling properties, they were fully composed by non‐toxic ingredients and resulted readily biodegradable in water, therefore easily disposable after the use.