“…Lead oxide is also used in glazes as a flux. Results present fairly consistent compositions for silica and lead, SiO 2 ranges between 35 wt % and 68 wt% with an average of 51.5 wt%, the same results was obtained by Gradmann et al (2015) for some samples collected from the same building (Fig. 4).…”
Section: Identification Of the Glaze Componentssupporting
confidence: 81%
“…Previous studies show that the white glaze in the Saadian monuments (e.g. El Badi Palace) is obtained by cassiterite (SnO 2 ) mixed with lead and silica (Gradmann et al, 2015;El Halim et al, 2018), but tin oxide cannot be detected by the Bruker AXS handheld analyzer instrument used (device detection limit). CaO can be used as whitening agents like SnO 2 but the higher lime contents observed in some white, black, yellow and green glazes (> 5 wt% of CaO) could also be due to efflorescence of the surface when the shard was made from calcareous clays (Walton and Tite, 2010).…”
Section: Identification Of the Colored Glazesmentioning
confidence: 99%
“…The need for having valid and useful heritage documentation is therefore evident and should constitute a priority action in any type of restoration (Almagro, 2013). Unfortunately, in these studied monuments, the availability of proper documentation is very limited (Gradmann et al, 2015;El Halim et al, 2018), as is the case in most historical monuments of emerging or developing countries in the South and East Mediterranean areas. To this end, the aim of this study is to characterize the chemical composition of the different glazes ceramics and to emphasize their evolution over time.…”
Archeological decorated ceramics from the Saadian tombs and El Badi palace sites (Marrakech, Morocco) have reached an advanced deterioration phase; the glazes have been increasingly weakened due to human and environmental impacts over time. Portable X-ray Fluorescence (pXRF) was performed in situ and on samples selected from these two monuments, in order to define the chemical agents responsible for the color of the studied glazed ceramics and to determine their evolution over time to help find answers and link between degradations and chemical compositions of different type of glazes. The results show that all samples are lead-silica type glazes with 25-59 wt% of PbO and 51 wt% of SiO 2 . The coloring agents used for the original glaze are conventional, copper (Cu 2+ ) for the green color, iron (Fe 3+ ) and manganese (Mn 2+ ) for the yellow and black glaze. Phosphorus (P 2 O 5 ), comes from carbonate mineral phases, is responsible for the blue opalescence of glazes. The study reveals that the ceramic industry has evolved recently in Morocco; elements such as calcium and potassium are currently used in small quantities while lead is increasingly used as flux in the glaze mixture. Iron and copper are still used for black, yellow and green colors, while the use of phosphorus has been replaced by other elements such as cobalt and copper.
“…Lead oxide is also used in glazes as a flux. Results present fairly consistent compositions for silica and lead, SiO 2 ranges between 35 wt % and 68 wt% with an average of 51.5 wt%, the same results was obtained by Gradmann et al (2015) for some samples collected from the same building (Fig. 4).…”
Section: Identification Of the Glaze Componentssupporting
confidence: 81%
“…Previous studies show that the white glaze in the Saadian monuments (e.g. El Badi Palace) is obtained by cassiterite (SnO 2 ) mixed with lead and silica (Gradmann et al, 2015;El Halim et al, 2018), but tin oxide cannot be detected by the Bruker AXS handheld analyzer instrument used (device detection limit). CaO can be used as whitening agents like SnO 2 but the higher lime contents observed in some white, black, yellow and green glazes (> 5 wt% of CaO) could also be due to efflorescence of the surface when the shard was made from calcareous clays (Walton and Tite, 2010).…”
Section: Identification Of the Colored Glazesmentioning
confidence: 99%
“…The need for having valid and useful heritage documentation is therefore evident and should constitute a priority action in any type of restoration (Almagro, 2013). Unfortunately, in these studied monuments, the availability of proper documentation is very limited (Gradmann et al, 2015;El Halim et al, 2018), as is the case in most historical monuments of emerging or developing countries in the South and East Mediterranean areas. To this end, the aim of this study is to characterize the chemical composition of the different glazes ceramics and to emphasize their evolution over time.…”
Archeological decorated ceramics from the Saadian tombs and El Badi palace sites (Marrakech, Morocco) have reached an advanced deterioration phase; the glazes have been increasingly weakened due to human and environmental impacts over time. Portable X-ray Fluorescence (pXRF) was performed in situ and on samples selected from these two monuments, in order to define the chemical agents responsible for the color of the studied glazed ceramics and to determine their evolution over time to help find answers and link between degradations and chemical compositions of different type of glazes. The results show that all samples are lead-silica type glazes with 25-59 wt% of PbO and 51 wt% of SiO 2 . The coloring agents used for the original glaze are conventional, copper (Cu 2+ ) for the green color, iron (Fe 3+ ) and manganese (Mn 2+ ) for the yellow and black glaze. Phosphorus (P 2 O 5 ), comes from carbonate mineral phases, is responsible for the blue opalescence of glazes. The study reveals that the ceramic industry has evolved recently in Morocco; elements such as calcium and potassium are currently used in small quantities while lead is increasingly used as flux in the glaze mixture. Iron and copper are still used for black, yellow and green colors, while the use of phosphorus has been replaced by other elements such as cobalt and copper.
“…The name µXRD is quite generic and can specify a variety of microdiffraction measurement modes, e.g., not only transmission (as is the case in this work) but also reflection ones. Reflection µXRD can be used for the identification of crystallites in glazes [115], but the transmission mode is definitely better. To specify that the measurement in the transmission mode is performed through a substrate supporting the specimen (e.g., a thin section on a glass-substrate), the prefix tts (through-the-substrate) was introduced [116].…”
Section: Tts-µxrd Applied To Petrographic Thin Sectionsmentioning
During the last thirty years, microstructural and technological studies on ceramic glazes have been essentially carried out through the use of Scanning Electron Microscopy (SEM) combined with energy dispersive X-ray analysis (EDX). On the contrary, optical microscopy (OM) has been considered of limited use in solving the very complex and fine-scale microstructures associated with ceramic glazes. As the crystallites formed inside glazes are sub- and micrometric, a common misconception is that it is not possible to study them by OM. This is probably one of the reasons why there are no available articles and textbooks and even no visual resources for describing and characterizing the micro-crystallites formed in glaze matrices. A thin section petrography (TSP) for ceramic glaze microstructures does not exist yet, neither as a field of study nor conceptually. In the present contribution, we intend to show new developments in the field of ceramic glaze petrography, highlighting the potential of OM in the microstructural studies of ceramic glazes using petrographic thin sections. The outcomes not only stress the pivotal role of thin section petrography for the study of glaze microstructures but also show that this step should not be bypassed to achieve reliable readings of the glaze microstructures and sound interpretations of the technological procedures. We suggest the adoption by the scientific community of an alternative vision on glaze microstructures to turn thin section petrography for glaze microstructures into a new specialized petrographic discipline. Such an approach, if intensively developed, has the potential to reduce the time and costs of scientific investigations in this specific domain. In fact, it can provide key reference data for the identification of the crystallites in ceramic glazes, avoiding the repetition of exhaustive protocols of expensive integrated analyses.
“…Therefore, studies on the old building materials must be conducted as a first step before taking any conservation or restoration decisions (Barluenga et al , 2013). In fact, with the exception of some recent studies that concern mainly Saadian tombs (Casas et al , 2008; Bendaoud et al , 2013; Gradmann et al , 2015) and the Saadian sugar factory of Chichaoua (Gamrani et al , 2012, 2014), very few scientific studies have been undertaken to characterize the materials used in the construction and restoration of these Saadian monuments. Fig.…”
Textural, mineralogical and chemical characterization of archaeological ceramics (zellige) from El Badi Palace (Marrakech, Morocco), the main Islamic monument from the Saadian period (sixteenth century), has been performed to enhance restoration and to determine the technology of manufacturing. A multi-analytical approach based on optical and scanning electron microscopy, cathodoluminescence, X-ray fluorescence and X-ray diffraction was used. Re-firing tests on ceramic supports were also performed to determine the firing temperatures used by the Saadian artisans. A calcareous clay raw material was used to manufacture these decorative ceramics. The sherds were fired at a maximum temperature of 800°C in oxidizing atmosphere. The low firing temperature for ‘zellige’ facilitates cutting of the pieces, but also causes fragility in these materials due to the absence of vitreous phases.
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