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The introduction of the glaze in al-Andalus: technological waves and Oriental influences

Periodic Reporting for period 1 - IGATO (The introduction of the glaze in al-Andalus: technological waves and Oriental influences)

Reporting period: 2016-09-15 to 2018-09-14

The project IGATO (The Introduction of the Glaze in al-Andalus: Technological waves and Oriental influences) has been devoted to develop a much-needed approach to the study of glazed ware production in al-Andalus (Spain and Portugal) during the Middle Ages (9th-13th centuries).

Before developing the project, we knew that the glaze technology started in the Iberian Penisula after the 8th century. However, we did not know how the glaze technology was introduced and we were not able to distinguish when the technology reached the Western Mediterranean basin neither knew of the existence of several waves of arrival. Our approach has been multidisciplinary, including historical documentation, archaeological evidences, collection of glaze ceramics and chemical and petrographic analysis of the glazes and ceramic bodies. The project has been conducted at UPC-BarcelonaTech (Spain) and the analytical work has been carried out mainly at the UPC Laboratories.

This proposal aimed to enrich the knowledge about glazed ceramic technology in the Western Islamic world through the following objectives:

-Identification of the Mediterranean access routes

-Localisation of the early Andalusi glaze workshops and their spread and distribution through the Iberian Peninsula and other lands

-Study and analysis of the microstructure and composition of the glazes, the raw materials, colorants and decorative techniques used

-Assessment of the possible Eastern and North African Islamic influences, both regarding shapes and decorative patterns and also technological aspects

-The glazed ware in al-Andalus has been recognized as an element of political cohesion, social distinction and, of course, as a sign of religious identity

A main social achievement has been the understanding of the relevance of the glaze technology as a part of our intangible heritage and as a means of culturalisation. Moreover, this project has brought a part of its history closer to the society, through the dissemination activities performed.
The research project has progressed according to its pre-planned timetable and the work has been performed as follows:

-A fieldwork and labwork phase was developed (WP1), including sampling of more than 100 ceramic shards from museums and collections, sampling preparation (polished sections, thin polished sections) and analyses including OM, PM, SEM-EDS, SEM-FIB and XRD.

-Characterisation of the different early glaze technologies (WP2); identification and distinction among the first three glaze productions in al-Andalus, Pechina, Córdoba and Málaga workshops (9th century), and the first tin-glaze production of Córdoba (10th century), and the identification of some imports (from Iraq and Ifriqiya). The results have been updated to the glazed ceramic database.

-Replication of the processes followed in the earliest glazed ceramic workshop of Pechina has been performed to understand the various stages of the complex process involving the glaze production (WP3). This activity was developed in the University of Vic. A comparison of the results obtained by replication with the data extracted from the study and analysis of the ancient materials from the workshop has been carried out.

-A set of actions have been developed to increase the visibility of the project and to spread the knowledge of the results obtained (WP4): creation of a technical Blog, participation in 17 conferences, workshops, courses, talks and at the European Research Night, creation of a Glaze network, establishing collaborations with the University of Oxford (including the study of Yellow Glazes, Egyptian Glazes and the Petrographic characterisation of al-Andalus glaze workshops), with the Research Group on Islamic Ceramic of Gharb al-Andalus, Portugal (studying the spread of the first glazes in the South West al-Andalus) and with the University of Sheffield (studying the relationship between the early glazed ceramics from Sicily and al-Andalus), and by organising in collaboration with the National Museum of ceramic (Valencia) the first International Workshop of Glaze technology. Furthermore, the main results obtained are published hitherto at different levels (4 peer-reviewed high-impact international journals, 2 national journals, 3 conference proceedings, 1 book chapter, and the blog entries).
IGATO shed a new light about the beginning of the glaze technology in the western Islamic world. The main results from this project can be categorised into seven points:

- The three earliest glazed ceramic productions centres (second half of the 9th century) in Medieval Iberia have been studied and their productions have been characterised, both fabrics and glazes. All the workshops initially produced lead transparent glazes with incised decoration.

- At the beginning, early glazed ceramics were not used in Medieval Iberia as an element of political cohesion nor religious identity, but as social-economic differentiation item of an elite who wanted to emulate the Abbasid court and the Oriental trends. On the contrary, from the mid-10th century onwards, the tin-glazed ceramics were used as a sign of political and religious power.

- The chaîne opératoire at the Pechina workshop has been determined; the glaze manufacture involved a complex process of fritting, that included several stages: from roasting the galena to obtain PbO, production of what we called a pre-frit then a frit, application of the glaze frit to the biscuit fired ceramic and a second firing of the object.

- The transition from lead transparent to tin-opaque glazed productions in the western Islamic lands (c.875-929 AD) has been traced.

- The provenance of tin-glaze technology has been addressed and the studies performed suggested a connection with the Abbasid world and not with the North Africa contrarily to what has traditionally been thought.

- Al-Andalus has been identified as the first place of the central and western Mediterranean, where the tin-glaze technology was developed (late 9th-early 10th centuries).

- The third technological wave, the lustre technology, has been determined and the probably earliest production centre of al-Andalus, located in the Alcazar of Sevilla (mid-11th century AD), has been studied.

IGATO has provided increasing awareness and understanding of the impact and relevance (social status, political cohesion and religious identification) of the glaze technology in the western Mediterranean world during the Middle Ages.

The exploitation and dissemination of the results have been carried out through talks, courses, conferences, participation in events, posters, leaflets, blog entries which received a positive feedback from the general public, with a high turnout of the activities proposed.

A network on glaze technology has been implemented, with the collaboration of researchers, both from academia and archaeological professional labour market. The creation of the open data website where the results of the IGATO project are updated along with the glaze analyses data from other research projects, allow anyone interested to have free access to the data and to enhance their knowledge and develop their research. The launch of the WM Glaze website took place during the celebration of the International Workshop on Glaze technology that was organised and held in collaboration with the Museo Nacional de Cerámica de Valencia. Furthermore, the Workshop proceedings are being published.
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