A. Duran’s research while affiliated with Universidad de Navarra and other places

Tiebas Castle was built between 1254 and 1264 as a royal residence of the kings of Navarre. The Castle was decorated with architectural luxuries imported from the French court. Some decorative elements of this French style are the polychrome roof tiles, called tuiles vernissées; and the glazed floor tiles, called carreaux de pavement. Both are the unique that have been found in the Iberian Peninsula. Elemental and mineralogical analysis allowed us to distinguish two different types of pastes that were used for both tuiles vernissées and carreaux de pavement: yellowish and reddish. The reddish paste was composed mainly of quartz, and to a lesser extent of haematite and illite. The yellow pastes were very rich in calcite and other calcium-bearing minerals (gehlenite, anorthite, diopside or wollastonite) and poorer in quartz and haematite. The different colour tones of the yellow paste samples allowed them to be classified into five subgroups (YP-1, YP-2, YP-3, YP-4, and YP-5). This classification turned out to coincide with a somewhat different mineral composition. The study of the mineral phases newly formed (gehlenite, anorthite, diopside and wollastonite) or destroyed (illite) during firing allowed us to estimate the maximum firing temperature of each of the subgroups. The temperature ranges for each subgroup were as follows: 750–800 °C (YP-5), 850–900 °C (YP-4), 900–925 °C (YP-3), 925–950 °C (YP-2), and 950–1000 °C (YP-1). The study of its possible raw materials allowed us to identify that the yellow pastes from tuiles vernissées and carreaux de pavement were prepared from a mixture of two clays. One of them was the decalcification clay (A15 clay) with which they also made the reddish pastes. The other component of the mixture was the marl from Castle hill. The proportion that the artisans used of both raw materials was 1:2 (twice as much marl as decalcification clay).

The objective of this study was to determine the authorship, provenance, and technology of the mudejar enamelled tiles from the Olite Castle (northern Spain, 14th century). According to previous knowledge, Olite’s enamelled tiles had been manufactured in Manises (Valencia, Spain). The analysis of ceramic pastes revealed the existence of two different chemical compositions, suggesting the use of two different clay sources, probably one from the Tudela area, and another from the Tafalla–Olite area. Those probably made in the Tudela area stood out with a higher diopside (CaMgSi2O6) content. Those probably made in the Tafalla–Olite area stood out for their calcium-bearing minerals, such as calcite (CaCO3) or gehlenite (Ca2Al(AlSi)O7). On this basis, production in Manises has been ruled out. However, it is highly probable that the artisans of Manises would have led the production from Tudela. The study of the firing temperatures and composition of the enamels indicated that the production methods and materials used in Tafalla–Olite (800–850 °C) and Tudela (higher than 900 °C) were different, reflecting the influence of local and Manises artisans, respectively. In Olite tiles, enamel was applied following recipes from the 14th and 15th centuries.

The Kingdom of Navarre was a Christian kingdom located in the north of the Iberian Peninsula during the Middle Ages. Its location on the west of the isthmus between the Iberian Peninsula and the European continent allowed an exchange of cultural currents. The main pottery production centres were in Estella, Lumbier, Pamplona, Tafalla, and Tudela. Ceramic pastes from various mediaeval sites were analysed for both elemental and mineralogical composition determination. The results were evaluated using Principal Component Analysis and allowed us to identify each production centre. Each manufacturing centre showed a different and characteristic composition of raw materials. Ceramics from Tudela were Ca-, Mg-, Na-, and Sr-rich. Ceramics from Estella were richer in Al, K, and Ti. Ca, Sc, and Sr contents were higher in Tafalla ceramics. Lumbier ceramics stood out for being enriched in Si, Mn, Fe, and Zr. Pamplona ceramics showed intermediate values. The analysis of samples from other Navarrese locations allowed us to begin to define what the commercial ceramic network in the Kingdom of Navarre was like during the Middle Ages. Therefore, two aims were defined for this paper: to characterise the ceramic pastes for each of the producing centres and to know where the ceramics were exported to.

The entrance of the Madre de Dios convent in Seville was carved in stone by Juan de Oviedo y de la Bandera, an important sculptor who made great artistic productions, highlighting his carvings in wood and stone. Several studies have been carried out on the carvings in wood, but no interest has been paid by experts to the carving pieces in stone. In this work, this polychrome made on stone around 1590 was studied for the first time. Micro-samples were taken and studied using micro-analytical techniques (optical microscopy, SEM-EDX, colourimetry, XRD, FTIR, and Raman spectroscopy). The pigments (smalt, atacamite, malachite, copper resinate, cinnabar, red earth, yellow ochre, carbon, and bone black) and the consolidation product (acrylic resin, very possibly Paraloid B72) were characterized. The experimental study indicated that the polychrome was applied on a layer of white lead (cerussite and hydrocerussite) that was laid on the substrate stone, constituted by calcarenite. This study also includes a comprehensive discussion on the use of these materials and techniques in other artworks within Seville’s cultural heritage.

Seville is intimately linked to its historic role and extensive cultural heritage. The city has been occupied by Romans, Arabs and Christians, who built important historical buildings. Roman (first–second centuries) and Arabic (eleventh century) buildings, medieval Shipyard (thirteenth century), San Isidoro and Santa Maria de las Cuevas monasteries (fifteenth century), Santa María de las Cuevas (fifteenth century modified in eighteenth century), El Salvador Church (eighteenth century), the Royal Ordnance building (eighteenth century) and Santa Angela de la Cruz convent (twentieth century) performed with lining mortars, and mortars used in building stones (City Hall and Marchena Gate), all of them located in Seville (Spain), have been studied. Ninety-four mortar samples (employed as structural, plaster, coating) originally used or applied in restoration processes have been collected to perform an archaeometry study. The ratio of CO 2 mass loss to hydraulic water (H 2 O) mass loss, and the mineralogical characterization by X-ray diffraction has been used to compare the mortars used in the different historical periods. Mainly hydraulic mortars were widely used in all these studied monuments as most mortars showed CO 2 /H 2 O ratios within the 4–10 range. Moreover, the thermal analysis curves also showed a broad temperature range for the thermal decomposition of the carbonate fraction of the mortars.

In this paper, the mesophilic Biochemical Methane Potential of several fabrics was assessed at different Total Solid concentrations (1-4%TS). Physico-chemical techniques were applied to explore the arising structural changes on fibers during the anaerobic digestion process. Additionally, the modified Gompertz model was used to assess and compare the AD performance of the fabrics. In cellulose-based fibers the production of biogas was enhanced thanks to the easy solubilization of acetate, which is generated upon partial breakage of cellulose bonds. The crystallinity of vegetal fibers decreased significantly from day 19. The highest methane yields were attained for silk and wool fabrics at the lowest TS concentrations. Conformational changes in fibroin and keratin were detected. The highest degrees of degradation were observed in solid samples with lower solid concentrations. Accordingly, the maximum methane yields were reported in the reactors operating with lower TS.

Carreaux de pavement is a type of mediaeval tile common in northwestern Europe, whose method of producing has been unknown until now. In this article, the kiln firing conditions of the unique carreaux de pavement found in the Iberian Peninsula were determined by comparing the physicochemical and mineralogical properties of the archaeological tiles with those of some reproductions of the tile's body manufactured in the laboratory (replica) made by varying the firing temperature and time, as well as the sample size and thickness. The resistance to acid digestion exhibited by the fired samples was especially revealed. According to the results and the modelling performance with the collected data, it was established that the maximum firing temperature was between 900 and 975 • C, and the time was longer than 24 h. These results show the technology used by mediaeval French potters and are a basis for future studies.

The characterization of fabrics after applying different degradation conditions appears to be a key factor to understand their behaviour for different applications. Depending on the treatment, morphologic and polymorphic changes may arise in the polymeric chain structure that composes textile fibers. In this paper, a systematic and comparative study between different types of natural and synthetic textile fabrics was carried out in order to shed light on the structural changes occurring under acid and alkali treatments. The natural fabric polymers studied had a cellulose-based composition from plants (cotton, linen and jute), or a protein-based one from animals (silk and wool). The synthetic fabric was polyester. Different treatment times were assessed: 15 min, 1, 2, 4, 8 and 24 h and compared to the initial condition of the fabrics (standard). In the cellulosic fabrics, the alkali provoked the polymorphic transformation of the amorphous CI into CII. However, the acid treatment did not cause any remarkable alteration in the structure. In protein fabrics, the acid treatment increased the amorphicity of the structures, leading to further degradation but not affecting the conformation of proteins, and the alkali dissolved the fabrics. Polyester was not affected by the chemical solutions (neither acid nor alkali).

Revealing the mediaeval lead-glazing manufacturing technique of the carreaux de pavement from Tiebas (Navarra, Spain) 6th International Congress "Chemistry for Cultural Heritage" Ravenna, 4th-8th July 2022 Lead-based compounds have been used as glazes in ceramics since ancient times [1]. In this communication, the glazed tiles of the Castle of Tiebas (Spain) were studied [2]. These specific type of tiles, known as carreaux de pavement , were a stylistic import from northern France [3,4]. Dichromatic tiles can be identified by their three-layered body: a top layer covered by a thin layer of lead glaze with colour; a middle layer, also known as engobe, consisting of a thin paste composed of clay or lime; and a bottom layer, which is also the thickest, named paste and made up of reddish clay. Monochrome tiles have only two layers: paste and glaze. In order to identify the lead-glazing manufacturing technique employed during the Middle Ages, replicas have been studied under different experimental conditions (Fig. 1). Both, replicas and archaeological samples were analysed and compared to estimate the original manufacturing conditions. As a base for the replicas, prismatic probes of decalcified clay (simulating the body) or kaolin (simulating the engobe) were used, with dimensions of 2 x 2 cm and 1 cm thick. Different amounts of lead-based compounds (PbS, Pb⁰, PbCO₃ and PbO) were applied by brush to the surface of these probes: in quantities of 20, 30 and 40 mg/cm². Following the results of previous research [5,6], replica samples were fired at different times (12, 24 and 48 hours) and temperatures (850, 900 and 950 ºC). Fig. 1. Scheme of the glazing method determinaton through experimental archeology.

Tiebas Castle (Navarra, Spain) was built in the mid-13th century as a sign of ostentation and power for the newly crowned Teobaldo II of Navarre. The castle was designed following the canons and luxuries of the French court to which Teobaldo II belonged as Count of Champagne. One of these luxuries was tiling the castle floors with decorated glazed ceramics, called carreaux de pavement . This type of mediaeval tiles reached its maximum diffusion in France and England between the 12th and 14th centuries. The manufacturing technique of these tiles has been unknown until now. Through experimental archaeology, replicas were made and simultaneously analysed together with the original archaeological samples found in the Castle. To achieve compatibility with the elemental and mineral composition of the original samples, a local decalcification clay was used as raw material for the replicas. Additionally, they were constructed using similar thicknesses (1 cm and 2,5 cm) as the archaeological samples. The replicas were fired at different temperatures (700, 800, 850, 900, 950, 1000 and 1100 ºC) and times (1, 3, 6, 24, 48, 72 hours). The analytical techniques used were the following: acid digestion, colorimetry, compressive tests, Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF) and X-ray diffraction (XRD). One of the key variables used to follow the changes produced during the firing processes was the hematite crystal size. Sintering and internal reduction of porosity during firing led to resistance to attacks by aqua regia (3 HCl + HNO3) to generally soluble elements at low pH, e.g. Fe. The results of hematite crystal size and %SiO2 and %Fe2O3 of the solid residue (after the acid attack) were used to build an empirical model that determined the firing time and temperature of the archaeological samples. Some mineralogical phases were also useful to confirm the firing temperature range like the absence of mullite and cristobalite, high temperature phases (≥1000 ºC) or illite, low temperature phase (≤850 ºC). Our study concluded that the firing time of the archaeological samples was higher than 24 hours and the firing temperature range was between 875 and 950 ºC. The results not only allow us to estimate a narrow range of firing temperatures, but also serve as a basis for future investigations on the manufacturing technology of the upper layers (engobe and glaze) of these types of ceramics. Tiebas Castle (Navarra, Spain) was built in the mid-13th century as a sign of ostentation and power for the newly crowned Teobaldo II of Navarre. The castle was designed following the canons and luxuries of the French court to which Teobaldo II belonged as Count of Champagne. One of these luxuries was tiling the castle floors with decorated glazed ceramics, called carreaux de pavement . This type of mediaeval tiles reached its maximum diffusion in France and England between the 12th and 14th centuries. The manufacturing technique of these tiles has been unknown until now. Through experimental archaeology, replicas were made and simultaneously analysed together with the original archaeological samples found in the Castle. To achieve compatibility with the elemental and mineral composition of the original samples, a local decalcification clay was used as raw material for the replicas. Additionally, they were constructed using similar thicknesses (1 cm and 2,5 cm) as the archaeological samples. The replicas were fired at different temperatures (700, 800, 850, 900, 950, 1000 and 1100 ºC) and times (1, 3, 6, 24, 48, 72 hours). The analytical techniques used were the following: acid digestion, colorimetry, compressive tests, Fourier transform infrared spectroscopy (FT-IR), X-ray fluorescence (XRF) and X-ray diffraction (XRD). One of the key variables used to follow the changes produced during the firing processes was the hematite crystal size. Sintering and internal reduction of porosity during firing led to resistance to attacks by aqua regia (3 HCl + HNO3) to generally soluble elements at low pH, e.g. Fe. The results of hematite crystal size and %SiO2 and %Fe2O3 of the solid residue (after the acid attack) were used to build an empirical model that determined the firing time and temperature of the archaeological samples. Some mineralogical phases were also useful to confirm the firing temperature range like the absence of mullite and cristobalite, high temperature phases (≥1000 ºC) or illite, low temperature phase (≤850 ºC). Our study concluded that the firing time of the archaeological samples was higher than 24 hours and the firing temperature range was between 875 and 950 ºC. The results not only allow us to estimate a narrow range of firing temperatures, but also serve as a basis for future investigations on the manufacturing technology of the upper layers (engobe and glaze) of these types of ceramics.