Raman spectroscopy has been widely applied in the analysis of different types of artwork. This technique is sensitive, reliable, non-destructive and can be used in situ. However, there are few references in the literature regarding specific Raman spectra libraries for the field of artwork analysis. In this paper, the development of two on-line databases with Fourier transform Raman (FT-Raman; 1064 nm) and dispersive Raman (785 nm) spectra of materials used in fine art is presented; both are implemented in the e-vibrational spectroscopic databases of artists' materials database (e-VISART). The database provides not only spectra, but also information about each pigment. It must be highlighted that for each pigment or material several spectra are available from different dealers. Some of the FT-Raman spectra available in the e-VISART database have not been published until now. Some examples in which the e-VISART database has been successfully used are presented.

The effects of the dry and wet acid deposition from both combustion and greenhouse gases (mainly CO 2 , SO x and NO x ) can be observed in the stones, mortars, bricks and decorative materials used in Built Heritage elements. Those deposition phenomena have greater effects in urban atmospheres, especially in medium or highly polluted ones. Most of the products formed as a consequence of decaying are alkaline and alkaline-earth oxoanions, which show, in general, a medium or high Raman scattering. The coupling of the experimental evidence (the detection of some metal-oxoanionic compounds by Raman spectroscopy) with the knowledge of chemical equilibrium is presented in this work as a tool to diagnose the impacts of CO 2 , SO x and NO x on the properties of Built Heritage. The compounds identified by Raman spectroscopy on different materials sampled in buildings of the Metropolitan Bilbao area (North Spain) included nitrocalcite, nitratine, nitromagnesite, nitrobarite as well as gypsum and soot as part of the black crust on carbonate-based materials, whereas calcite, natron, nitratine and mirabillite were recognised as composition of the white efflorescence in non-carbonate materials and mortars. An overall degradation pathway is proposed to explain the formation of each decayed compound as a function of the original characteristic material.

Non-destructive and non-invasive micro-Raman fibre optic and micro-XRF analyses were performed to study a wallpaper from the beginning of the 19th century. The complementarity of these two non-destructive techniques is shown in this work. The analysed artwork is considered one of the most beautiful wallpapers ever manufactured according to the catalogues and books; it is known as Chasse de Compiègne, manufactured by Jacquemart, Paris, in 1812. During the analysis, an unexpected pigment was detected by both analytical techniques: lead-tin yellow type II. This pigment was used until ca. 1750, when other yellow pigments replaced it, thus it is very difficult to find it in paintings afterwards. Together with this pigment, red lead, Prussian blue, brochantite, yellow iron oxide, calcium carbonate, vermilion, carbon black of animal origin (bone black), lead white, and raw and burnt sienna were also determined by combining the analytical information provided by both techniques. A possible degradation of brochantite to antlerite is also discussed.

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One of the earliest wallpapers manufactured by the Santa Isabel factory (Vitoria, Basque Country, Spain) (1845) was found at the Torre de los Varona (near Vitoria) during restoration work on the building. As part of this cleaning and restoration work, the identification of the wallpaper's pigments was carried out by Fourier transform (FT) Raman spectroscopy. Fragments of paper were set in a sampler kit for planar surfaces. By moving the paper samples, it is possible to locate the laser beam's spot at the point that it is going to be analysed with a spatial resolution of about 0.5 mm. With this method it is possible to map a surface of several square centimetres without the need for an optical microscope. As FT-Raman analysis is totally non-destructive, the samples were restored and integrated with the whole wallpaper at the end of the analysis. Small particles of pigment were collected for the analysis of the pink and green colours by atomic absorption spectrometry (AAS). In both cases, the damage caused by the pigment sampling was minimal and non-visible. BaSO 4 , CaCO 3 , Pb 3 O 4 , PbCrO 4 , PbO, Prussian Blue, gypsum and an organic black pigment were detected. It is important to take into account the laser beam's penetrative power in order to interpret the spectra correctly. The identification of only eight pigments to make 12 different colours, mostly in two different shades, shows the ability of the wallpaper manufacturer to create a rich palette at low cost. This type of primitive industrial decorative work has become real artwork that it is necessary to preserve and restore.