This work explores the combination of µ-Raman spectroscopy and scanning electron microscopy with X-ray energy dispersive spectrometry (SEM-EDS) for the study of the glazes in 15th-16th century Hispano-Moresque architectural tiles. These are high lead glazes that can be tin-opacified or transparent, and present five colors: tin-white, cobalt-blue, copper-green, iron-amber, and manganese-brown. They are generally homogenous and mineral inclusions are mostly concentrated in the glaze-ceramic interface. Through SEM-EDS, these inclusions were observed and chemically analyzed, whereas µ-Raman allowed their identification on a molecular level. K-feldspars, wollastonite and diopside were the most common compounds, as well as cassiterite agglomerates that render the glaze opaque. Malayaite was identified in green glazes, and andradite and magnesioferrite in amber glazes. Co-Ni-ferrites were identified in blue glazes, as well as Ni-Fe-olivines. Manganese-brown is the color where most compounds were identified: bustamite, jacobsite, hausmannite, braunite, and kentrolite. Through the µ-Raman analysis of different areas in large inclusions previously observed by SEM, it was possible to identify intermediate phases that illustrate the reaction process that occurs between the color-conferring compounds and the surrounding lead glaze. Furthermore, the obtained results allowed inference of the raw materials and firing temperatures used on the manufacture of these tiles.

For the first time, Hispano-Moresque glazed tiles from Portuguese and Spanish collections were studied together and compared. This work is included in a wider study tackling the technology of Hispano-Moresque tile production from several collections in the Iberian Peninsula. While showing many similarities, differences were identified between collections, regarding both chemical and morphological characteristics. The collection from the Mosteiro de Santa Clara-a-Velha (Coimbra) stands out from the other collections, with higher SnO2 content (up to 14¿wt%), the highest Fe2O3 contents in amber glazes and a Ca-rich interface layer (mostly comprised of wollastonite, CaSiO3). Samples from Palácio Nacional de Sintra (near Lisbon) and Seville-attributed samples (from the Instituto Valencia de Don Juan) are chemically similar, except that most Sintra's samples display a K-rich glaze/ceramic interface, whereas the ones from Seville exhibit both K-rich and Ca-rich inclusions. The samples attributed to Toledo show glazes with many inclusions, contrasting with the homogeneous glazes in most Hispano-Moresque tiles. From these results, we identify differences that can be used as markers in future studies on Hispano-Moresque tiles.Peer ReviewedPostprint (author's final draft

This work comprises the use of a multi-analytical approach combined with microbiological studies to characterize six paper samples, containing foxing stains, from the 20th century, regarding their cellulose matrix, fillers, and sizing materials, and to evaluate possible paper degradation that might have occurred during the foxing stains. Photography under different illuminations and optical microscopy were used for morphological characterization of the paper samples and foxing stains. Scanning electron microscopy coupled energy dispersive spectroscopy (SEM-EDS) was of particular importance for defining the presence of fiber disorder and disruption on the surface of some of the stains, and localized accumulations of mineral-like particles on the surface of others. SEM-EDS, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FT-IR), and energy dispersive X-ray fluorescence (EDXRF) were used for the identification of mineral fillers, whereas sizing agents were analyzed using ATR-FT-IR. EDXRF results showed that no differences, within the standard deviation, were found in iron and copper contents between the foxed and unfoxed areas. Fungi belonging to the genus Penicillium spp. were found in all the paper samples. Unfoxed areas presented lower contamination than the foxed areas.

Deterioration of graphical documents can occur naturally as a result of aging, but it can be accelerated by poor manufacturing constituents or conditions. One indicator of deterioration can be discoloration or staining of the surface [1][2][3]. Among these paper discoloration processes is foxing, which has been actively researched since the 1930s. Our attention herein is focused on trying to elucidate its causes and to establish protocols for detection, prevention and treatment. This foxing phenomenon occurs in the form of small isolated patches of discoloration that are typically rust, brown or yellowish toned and limited in size, with sharp or jagged edges; it is often punctiform and sometimes circular [4]. A long discussion about the origin of foxing has been undertaken, being the major causes attributed to fungal activity or to chemical origin. In fact, sometimes biological attack is the only factor observed, while in others metal-induced degradation is present and interaction between both factors can also be found [5]. During the last few decades, different analytical techniques have been used for the study of the foxing processes; nevertheless there is still much to be done [4,5]. Four different foxed papers from the XX century, labelled P1, P2, P3 and P7, were studied. Characterization of paper samples and morphological aspects of foxing was undertaken by analytical techniques and imaging: photography and macro-photography under standard light, UV/Vis fluorescence light and raking light; light microscopy; variable pressure scanning electron microscopy with energy dispersive X-ray spectrometry (VP-SEM/EDS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FT-IR). Biological colonization was also studied in order to evaluate the influence of microorganisms in foxing. Photographic imaging allowed to evaluate the natural colours of paper samples and their state of degradation, namely, the presence of dirt, foxing stains, wear, and others (Table 1). The foxing stains of P3 sample were the only ones to exhibit fluorescence under UV light. Morphological aspects of the foxing stains were observed by SEM/EDS operating in variable pressure conditions (pressure of 20 Pa in the chamber). Two different typologies were devised. In samples P1, P2 and P3, fibre disruption was observed in the foxed areas (Figure 1), when compared with the non-affected areas of those samples. As to sample P7, a localized accumulation of particles was observed in the foxed areas, which were confirmed to be a calcium salt due to Ca detection by EDS analysis. Different fillers used in paper production were also estimated through EDS. ATR-FT-IR complemented the study and was particularly adequate to evaluate the existence of biotic attack in the foxed areas of all the papers. ATR-FT-IR was also able to supply information about the fillers and the FT-IR bands related to cellulose suggesting alterations of the cellulose structure in the foxed areas (Figure 2). Fungi belonging to the main genera Penicillium sp. were iso...

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