the introduction of the glaze in al-andalus: technological

The introduction of the glaze in al-Andalus: Technological waves andOriental influences

By Elena Salinas and Trinitat Pradell

AbstractThis research develops a much-needed approach to thestudy of glazed ware production in al-Andalus (MuslimSpain and Portugal) during the early Middle Ages. Theintroduction of glaze to the Iberian Peninsula was a longand complex process involving three waves of technologytransfer arriving from the eastern Islamic regions betweenthe ninth and eleventh centuries. In this paper, the mainglaze workshops of each technological wave have been char-acterised in order to understand how the medieval techno-logical transmission took place and how political andeconomic factors influenced this gradual dissemination.

انيليإةيقرشلاتاريثأتلاوةيجولونكتلاتاجوملا:سلدنلأاىلإجيجزتلالاخدإ

ليداربتاتينيرت،سانيلاس

ةججزملايناولأاجاتنإةساردلةدشبابولطماجهنثحبلااذهروطي

)glazed ware(سلدنلأايف)روصعلاللاخ)لاغتربلاوةملسملااينابسإ

ةيلمعةيريبيلإاةريزجلاهبشىلإجيجزتلالاخدإناكدقل.ةركبملاىطسولا

قطانملانمةمداقلاايجولونكتلالقننمتاجومثلاثتنمضتثيح،ةليوط

فصومت،ةقرولاهذهيف.رشعيداحلاوعساتلانينرقلانيبةيقرشلاةيملاسلإا

ةيفيكمهفلجأنمةيجولونكتةجوملكلةيسيئرلاجيجزتلاشروزييمتو

ةيسايسلالماوعلاترثأفيكوىطسولاروصعلايفيجولونكتلالاقتنلااثودح

.يجيردتلاراشتنلاااذهىلعةيداصتقلااو

IntroductionAlthough the Romans produced lead-glazed ceramicson the Iberian Peninsula, this technology subse-quently disappeared. In fact, some vessels from lateantiquity contexts that were formerly identified as‘glazed ceramics’ have recently been recognised ascrucibles for glass production (Peña et al. in press).Glaze technology was reintroduced to Iberia fromthe Islamic world in several technological waves.This technological transfer did not reach thePeninsula – which was conquered by the Arabs andBerbers in 711 CE – in the early days of al-Andalus,in spite of the spread of glaze technology throughoutthe eastern Islamic lands (Syria, Egypt, Iraq, etc.). Thefirst evidence of glazed ware production has to be

dated to the second half of the ninth century inPechina (Castillo and Martínez 1993).

We began with the initial hypothesis that the mainearly production and exporting centre of transparentglazed ceramics was located in Pechina (Salinas andZozaya 2016). There is also archaeological evidenceof a later glaze workshop in Málaga (Íñiguez andMayorga, 1993). No more evidence of early glazeproduction centres has been found, other than thatof Córdoba, which was identified during the courseof this investigation. It has been proposed that therewas a single polychrome tin-glaze workshop, part ofa centralised monopoly (Rosselló 1995), during theCaliphate of Córdoba (929–1031 CE). The fitna orcivil war (1009–31 CE) led to the collapse of thecaliphate and the fragmentation of power into several‘Taifa’ kingdoms (1031–85 CE). One of the conse-quences of this was that tin-glaze technology spreadto the new capitals of the kingdoms, coinciding withthe beginning of lustre production.

Unlike in the eastern Islamic regions, the transmis-sion of glaze technology know-how in al-Andalus didnot take place all at once. In fact, it needed over twocenturies of assimilation and was heavily conditionedby political and economic events. Three technologicalglaze waves can be identified: the first in the mid ninthcentury with the production of transparent glazes; thesecond in the early tenth century, comprising the pro-duction of opaque tin glazes; and the third in the mideleventh century, involving the production of lustre-decorated wares (see Table 1).

With regard to the first wave, we focused onsouthern Iberia (Fig. 1), sampling 16 of the 30 previ-ously identified glaze finds from the emirate ofCórdoba (Salinas and Zozaya 2016). We followed aquantification criteria, as most of the northern sitesonly contained one or two glazed samples, whereasthe studied settlements had more – between threeand 1,500 (the latter from a workshop area). Theymade up the bulk of this study, with a total of 152early glazed samples analysed. In order to understandthe transition to the second wave, 40 samples fromfour sites were selected for study. Finally, the thirdwave was addressed by analysing three pieces of evi-dence from the only possible lustre workshop identi-fied so far. There may have been another productioncentre in north-eastern Iberia (Ortega et al. 2013),

‡The original version of this article was published with the incorrectabstract. A notice detailing this has been published and the error rectified inthe online PDF and HTML copies.

Characterisation of Materials Group (GCM), Physics Department,Universitat Politècnica de Catalunya (UPC-BarcelonaTech), Av. EduardMaristany 16, Barcelona 08019, Spain

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but no archaeological evidence for it has yet beenfound. In addition, six glazed imports were analysedin order to determine their possible influence on thelocal productions.

Our approach was multidisciplinary and includedhistorical documentation, archaeological evidence, thesampling of glazed ceramics from well-contextualisedarchaeological excavations, and chemical and petro-graphic analyses of ceramic bodies and glazes.

Glaze technologies in medieval SpainFrom the study and analysis of glazed ceramic sherds,we were able to distinguish several glaze and decora-tive technologies related to the three waves (Table 2).In particular, we distinguished between plain trans-parent lead glazes, polychrome transparent leadglazes, polychrome opaque tin glazes and lustredesigns. The main production centres related to thethree technological waves identified so far areshown in Fig. 2.

First glaze technological waveAfter revising archaeological finds from the potterycraft quarters of Málaga, Córdoba and Pechina,their glaze productions have been identified andcharacterised. These earliest glazed ceramic work-shops specialised in glazed tableware and oil lampswith transparent lead glazes, incised decoration,and one or two plain colours applied over each sur-face. They were in operation during the late ninthand early tenth centuries (Fig. 2).

The composition and technological features ofthe ceramic pastes and fabric groups were studiedto determine their geographical area of origin andto confirm their provenance (Table 2 and Fig. 3).Pechina ware is calcareous (15–20% CaO) withfine metamorphic inclusions (mica and schist) and abuff-coloured fabric. Córdoba ware is also calcareous(10–15% CaO) with fine sedimentary inclusions(quartz, feldspar, mica and some fossil foraminifera)and coarse round white calcareous and red iron-richinclusions; the predominant colour is orange.

Figure 1. Localisation of the archaeological sitessampled. (1) Pechina. (2) Murcia. (3) Madinat Ilbira.(4) Marroquíes Bajos. (5) Puente Tablas. (6)Calatrava la Vieja. (7) Córdoba. (8) Madinatal-Zahra. (9) Alfarnate. (10) Valsequillo. (11)Vélez-Málaga. (12) Bezmiliana. (13) Málaga. (14)Sevilla. (15) Mértola. (16) Silves.

Table 1 - Summary of historical context and glaze technological waves studied.

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Table 2 - Table with the different glaze and decorative technologies used in al-Andalus.

TW Technique Chronology Workshop Location Inclusions Decoration Patterns Colour Colorants Opacifiers Firing/s

1 Mono/Bichromeleadtransparent

Second halfof 9th C.

V Pechina Metamorphicmica, schist

Plain Incised GreenAmberTransparent

Cu, Fe 2


V Córdoba Sedimentaryquartz, feldspar,calcareous &iron-rich inc.

Plain incisedplastic

GreenAmber

Cu, Fe 2

10th C. V Málaga Sedimentaryflint, phyllite,quartz, shells

Plain incised BrownAmber

Mn, Fe 1?

Polychromeleadtransparent

Late9th-early10th C.

Córdoba?Pechina?

Sedimentaryfine quartz &mica

Overglaze SplashesGeometric

GreenAmberBrownTransparent

Cu, Fe, Mn 2

2 Polychrometin-opaque

Late9th-early 10th

C (Emiral)

Córdoba? Sedimentaryfine quartz,feldspar & mica

Overglaze Geometric GreenAmberBrownWhite

Cu, Fe, Mn SnO2 2

929–1010(Caliphal)

V Córdoba Sedimentaryquartz, feldspar,mica,calcareous inc.

Overglaze Geometric,Plant, Zoo,Epigraphic,Human

GreenAmberBrownWhite

Cu, Fe, Mn SnO2 2

3 Lustretin-opaque


V? Sevilla Sedimentaryfine and scarce

Lustretechnology

GeometricEpigraphic

Gold White Cu, Ag SnO2 3

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Málaga ware has a low calcareous content (5.5–8.5%CaO) with fine sedimentary inclusions (flint, phyl-lite, quartz and seashells) and an overall red colourwith white areas around the reacted seashells,which also provide a porous fabric.

With regard to the glazes, in addition to specificdecorative patterns and shapes, each production cen-tre had distinctive technical features in terms of thecolorants used and the glaze composition (Table 2and Fig. 4). Pechina glazes are characterised by ahigh lead content (∼60%PbO) and the use of twoplain colour glazes, green and amber, obtained byadding copper and iron oxides respectively. Málagaglazes have a lower lead content (∼40%PbO) andthe main colour is a chocolate brown obtained bythe combined addition of manganese and iron oxi-des. In contrast, the most representative Córdobaglazes are amber (with added iron oxide) and, to alesser extent, green (with added copper oxide), andintermediate lead content (∼50%PbO).

Although they initially produced glazed warewith different colours on each side, they later incor-porated polychromies (Tables 1 and 2), althoughwith some nuances. In fact, the earliest Pechinaworkshop presumably moved to a nearby area, prob-ably in the late ninth century, before this technicalchange was introduced. Archaeological excavationshave revealed evidence of polychrome glazed ceram-ics production in its activity area related to the newPechina workshop during the tenth century(Castillo and Martínez 1993). The Málaga workshopbegan operating in the early tenth century and, overthe years, added brown brush strokes over the amberglaze background, but no other coloured decoration.Each workshop had its own characteristics:

techniques, colorants, raw materials, compositionand style, vessel shapes and the application of thedecorations. All these elements created a distinctiveglaze tradition in al-Andalus, different to thosefrom other Islamic regions. Regarding the spreadand distribution of the different glazed ware produc-tion throughout the Iberian Peninsula, it has beenassessed that the three glazed ware productionshave been found outside their local markets.

In the case of Córdoba, an early transparent poly-chrome production of very short duration (green andbrown glazes over a transparent glaze) has been iden-tified at the turn of the tenth century (Salinas andPradell 2018). This production was rapidly replacedin the early tenth century by the polychrome tin-glazed ware related to the second technologicalwave. However, polychrome transparent lead-glazedware reappeared in Córdoba during the late tenthand early eleventh centuries, replacing the white back-ground opaque tin glaze with a transparent amberglaze. This could be related to the shortage of tin atthe end of the Caliphate and during the civil war, asthe tin sources located in western Iberia andCórdoba had lost control of those territories.

Second glaze technological waveThe first al-Andalus tin-glaze production specialisedin polychrome ware with simple green (copper)and brown (manganese) designs applied on one ofthe sides over a white opaque glaze backgroundachieved by the addition of cassiterite cassiterite(SnO2) (Table 1, Fig. 5). The undecorated side wasalso covered by a plain white tin glaze (Fig. 5).This production has been identified in the Emirate

Figure 2. The glaze production centres from al-Andalus corresponding to the three technological waves studied.

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in Córdoba (late ninth–early tenth century) and is acontinuation of the earlier polychrome transparentlead-glaze production in terms of its applicationmethod and designs – the overglaze painting of sim-ple patterns. The analyses carried out have revealed aconnection with the Abbasid world, probablyMesopotamia (present-day Iraq) (Matin et al. 2018)rather than North Africa. This is a significant out-come, as both lead- and tin-glaze technologies havetraditionally been linked to the Aghlabids (medievalIfriqiya, present-day Tunisia) (Rosselló 1995).

Later, polychrome tin-glazed ware continued to beproduced under the Caliphate (929–1031 CE), by thattime with more complex design patterns than in theEmirate. Moreover, the undecorated side was coveredby a transparent lead glaze, often amber-coloured,instead of a plain tin glaze. Subsequently, in the elev-enth century, tin-glaze technology spread acrossal-Andalus and other peripheral production centreslocated in the seats of the Taifa kingdoms emerged.

It should be highlighted that the existence of anearly tin-glaze production in al-Andalus has long

Figure 3. (Left) optical microscopy and (right) petrographic microscopy images of the ceramic fabrics from thethree workshops from the first technological wave: (a) Pechina; (b) Córdoba; (c) Málaga.

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been questioned due to the poor preservation of theglazes, leading it to be confused with slips (Escudero1991, 135). The glazes usually presented a low vitri-fied surface, muted brilliance and a dusty appear-ance. Analyses have demonstrated that thisappearance is due to the alteration of the glazes,the precipitation of lead carbonates and also phos-phates (see Fig. 5), together with the tin oxide parti-cles. The reasons for this lack of adequatepreservation of the glazes could be linked to the pro-cedure followed in the tin-glaze production or to theacidic nature of the soil in an urban environment.

Third glaze technological waveLustre was the most complex decorative techniqueand the last technological wave to reach al-Andalus(mid eleventh century). It is highly likely that theearliest lustre production centre was in the Alcazarof Seville (the palace of the local ruling dynasty).Two lustre rejects from this earliest production

Figure 4. SiO2 versus PbO composition of the glazescorresponding to the three workshops from the firsttechnological wave.

Figure 5. Optical microscopy and scanning electronic microscopy back scattering images and micro-X-raydiffraction analysis of a polychrome opaque glazed ceramic, dated in the Emiral period (late ninth–early tenthcentury), showing the presence of the dusty appearance of the glaze, the alteration shown which is identified aslead carbonate and lead oxide hydrate.

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were analysed and revealed the characteristic thinsilver- and copper-rich layer (≈1 μm thick) contain-ing a small amount of silver/copper metal (some

tens of nanometres in size) (Fig. 6). The productionfrom Seville can be compared to that from other lus-tre workshops in the Calatayud/Zaragoza area whichhave been analysed previously (Ortega et al. 2013).Comparison with contemporary production centres(Egypt, Tunisia and Syria) is also being carried outto ascertain the origin of the potters who broughtthe technology to al-Andalus.

Imported glazed wares and influencesA few glazed ceramics were identified as importedglazed ware from different Islamic regions and peri-ods (Fig. 7). A white opaque glazed example fromMesopotamia (Samarra type) (Carvajal 2013) and apolychrome transparent glaze from Ifriqiya werefound at Madῑnat Ilbira (ninth century). The whiteopaque tin glaze (Fig. 8a) is a characteristic AbbasidIraqi production, from a period in which plainwhite tin glazes were not produced in al-Andalus.Moreover, Iraqi white glazes are alkali-lead and con-tain a large amount of cassiterite particles (Matinet al. 2018), whereas later tin glazes fromal-Andalus are lead-alkali and contain fewer tinoxide particles. With regard to the polychrome trans-parent glazes, the Ifriqiya production began earlier(under Aghlabid rule, 800–909 CE) than theal-Andalus polychrome transparent glazes. TheIfriqiya glaze shows significant technological differ-ences (Fig. 8b). First, it has a thick creamy ceramicsurface layer between a red body and the transparentglaze, probably obtained by adding salted water tothe ceramic surface before biscuit firing. Moreover,colour decorations were applied on the ceramic sur-face below the transparent glaze or underglaze, whilein al-Andalus they were applied over the glaze.Finally, coloured glazes with a high lead contentwere manufactured in al-Andalus, while theTunisian glazes were lead-alkali (Ben Amara et al.2001).

Figure 6. Lustre sample analysed with scanningelectronic microscopy with focused ion beam,showing the presence of a surface thin layer of metalsilver nanoparticles and distribution of copper andsilver in the layer thickness.

Figure 7. Location of the proposed provenances for the ninth–tenth-century imports found in al-Andalus.

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Figure 8. Optical microscopy and scanning electronic microscopy back scattering images of the imported glazedwares: (a) Abbasid white ware, showing a thick homogeneous tin glaze; (b) polychrome glazed ware fromIfriqiya, showing the creamy ceramic surface, underglaze brown decoration and the transparent glaze on top; (c)Abbasid monochrome lustre ware, showing the characteristic thick glaze and microstructure (diopsides,cassiterite particles, bubbles and quartz grains); (d) sgraffitto ware, showing a thin heavily weatheredtransparent glaze on top of a white slip full of angular quartz grains.

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On the other hand, a set of Abbasid lustre wareand a sgraffito glazed dish from the palace area ofMadῑnat al-Zahra’ are the most significant imports(second half of the tenth century). No other contem-porary lustre or sgraffito examples have been foundin al-Andalus to date. The lustre ware was analysedin order to rule out a local provenance. Previousarchaeological studies proposed an Egyptian proven-ance (Heidenreich 2007); however, the chemicalcomposition of the ceramic pastes and glazes linksthem to the Abbasid lustre ware made in Iraq(Pradell et al. 2008) (Fig. 8c). This means that lustreware was used in the palace but not produced inal-Andalus in the mid tenth century. It took anothercentury for the lustre technology to reach al-Andalus.

Finally, the sgraffito dish (Fig. 8d) combines awhite slip, polychrome splashes and incised decor-ation under a transparent glaze – a technique thatwas never used in al-Andalus. In contrast, it waswidely produced in Iran and Central Asia duringthe tenth century (Watson 2004).

DiscussionVarious reasons can be identified for the beginning oflocal glazed ceramic production and how it relates toeach political period, settlement status and relevantevents in the history of al-Andalus. The workshopswere mainly in large urban locations. Córdoba wasthe capital of al-Andalus, the political, economic,religious and cultural centre of the Umayyad dynastyfrom the eighth to the early eleventh centuries.Pechina was the most important port and the gate-way for trade with the East in the ninth and tenthcenturies. It was enriched by the Mediterraneantrade and remained outside the central state rule ata time when Umayyad power was being weakenedby continuous rebellions. Málaga emerged as a seaport and was strategically placed to trade withAfrica and control the gold route during the tenthcentury. Finally, Seville was the capital of the ArabAbbadid dynasty and the most powerful kingdomduring the eleventh century, gaining control overalmost all of southern Spain and Portugal.

With regard to the relationship between the dif-ferent glaze waves and the cultural, economic, reli-gious and social changes, the first glaze productionin al-Andalus by the three identified workshops islinked to both a widespread rebellion against theEmirate of Córdoba (878–929 CE), which led to aperiod of political instability and weakness, and toa limited spread and use of glazed tableware by asmall segment of the al-Andalus population.Political instability and economic crisis (with a haltto monetary issues in Córdoba) may have prevented

the spread of the new technology. Archaeologicalfinds show that the early glaze production was notused as an element of political cohesion or religiousidentity, but as a socioeconomic distinction by anelite who wished to emulate the Abbasid court byadopting oriental trends. Furthermore, followingthis research, it has been demonstrated that Pechinawas not the only workshop with a regional distribu-tion network, as had traditionally been thought;Córdoba and Málaga glaze productions were alsosold outside their local markets.

The use of tin for the opaque glazes (secondwave) began in the unstable late-Emirate period(before 929 CE) and not during the Caliphate. Itappears that this new technology was first used inCórdoba, one of the three earliest glaze craft areas,where a previous market was consolidated. Thisearly polychrome tin-glazed ware presents very sim-ple patterns, far from the complexity and politicalmeaning of the later period. Another possible tin-glaze workshop may have operated in the Vega deGranada area (Molera et al. 2018), although no evi-dence of a workshop has been found so far. Themanufacture of this tin-glazed ware continued duringthe caliphate period, when the glazed ware consump-tion pattern changed. Transparent lead-glazed cer-amics were popularised and subsequently widelyused during the tenth and eleventh centuries. Thismass consumption led to a simplification of theglaze production process (from an extremely com-plex process in the ninth-century workshop ofPechina to a more simplified method in the tenthcentury in Malaga) and the proliferation of work-shops specialising in lead-glazed ware (e.g. Murcia,Toledo). Conversely, polychrome tin-glazed waretook over from the earliest transparent lead glazesand their consumption was restricted to a smallgroup of high-status consumers (especially outsideof Córdoba where the amount of polychrome tin-glazed ware is much lower). Moreover, from themid tenth century onwards, tin-glazed polychromeceramics were used as a sign of political and religiouspower by the Umayyad dynasty. This tendency seemsto have continued with the emergence of the lustretechnology. Two of the most powerful local dynas-ties of the Taifa kingdoms emulated the Fatimids,producing their own lustre ware and even decoratingit with the king’s name as a sign of their power(Table 1).

Considering the evolution of glaze technologiesin Iberia during those two centuries in relation tothe establishment of new workshops and the distribu-tion of glazed tableware, an obvious concentration ofglazed wares is found close to the identified

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production centres (Fig. 1). However, it is not theonly explanation for the slow spread of glaze tech-nology to the far west of Iberia (present-dayPortugal) (Gómez et al, in press), just as happenedin the northern territories (including the ChristianSpain). Several factors appear to have been involved– on the one hand, a later Islamisation and orientali-sation of both the population and their dining habits,since the use of sophisticated ceramic tableware diedout in Iberia during the Late Antiquity. On the other,it may have been due to the lack of a productionstructure and an organised trade network capableof supplying the entire al-Andalus market. Politicalor religious do not appear to have been determiningfactors; the use of glazed tableware was a symbol of ahigh status in keeping with eastern Islamic trends.

The spread of tin-glaze technology on a regionallevel is associated with the collapse of the Caliphateof Córdoba (late tenth–early eleventh centuries).Polychrome tin-glazed ware ceased to be an exclusiveproduction of the Umayyad capital, as new work-shops were established in other urban centres, thenew capitals of the Taifa kingdoms (e.g. Sevilla,Málaga, Denia, Zaragoza). During the civil war,most of the city of Córdoba was abandoned – includ-ing the ceramic workshops – and the populated areawas reduced to the walled city. Simultaneously, adiaspora of specialised potters spread tin-glaze know-how throughout al-Andalus.

Looking eastAnother important point has been to clarify the pos-sible technological transfers from other Islamic lands.Comparing the eastern Mediterranean and NorthAfrican technological glaze traditions with that ofIberia, we can see notable differences. Alkali glazesand slips were never used and underglaze decora-tions were not applied, at least by the Córdoba arti-sans. Nevertheless, the use of glazes with a high leadcontent and the application of decorations over awhite opaque background are also found on someof the Abbasid productions. However, the local pot-ters did not copy imported glazed ware, since thereare also evident differences in terms of vessel shapes(the lack of a foot on the dishes) and decorative pat-terns (the predominance of plant motifs, simpledesigns, etc.).

The situation seems different for the lustre tech-nology. Lustre began in the Abbasid caliphate, but itsexpansion to other regions was particularly slow andprogressive. The peculiarities and difficulties of lus-tre technology have always been considered respon-sible for its slow spread. Lustre did not reach theIberian Islamic kingdoms until the eleventh century

and its origin (directly from the Fatimid Caliphateor through North Africa-Tunisia) is still a matter ofdebate and further study. What is clear is thatSpanish lustre ware copied technology, decorationsand shapes.

Another aim has been to identify some of the net-works and commercial flows between the easternMediterranean regions and al-Andalus based on theceramics trade. The small percentage of glazedimports documented from other Islamic centres dur-ing the ninth and tenth centuries rules out the possi-bility of an organised, large-scale trade in glazedceramics in the western Mediterranean during theearly medieval period, unlike between Mesopotamiaand China or Japan (Priestman 2016). It is more likelythat glazed ceramics travelled individually along withpeople (e.g. on pilgrimages, as diplomatic gifts, etc.)or with other trading goods (e.g. silk fabrics), ratherthan as a main trading product. However, accordingto the archaeological evidence on the IberianPeninsula (e.g. Denia or Mértola), foreign glazed cer-amics became more common in al-Andalus from theeleventh century, a period that coincides withFatimid control of the Mediterranean routes.

Furthermore, the technology of the glazedimports studied was not copied by local potters andtheir shapes and decorations had little influence onthe al-Andalus productions. It suggests that theknowledge of medieval glaze techniques was trans-ferred directly by potters, who migrated and estab-lished new workshops, and not by treaties. Shapesand especially decorations appear to have beenadapted to the local tastes.

ConclusionA progressive introduction of glaze technologythrough three technological waves has been revealed.However, they arrived with some delay with respectto the eastern Islamic regions. The few items ofimported glazed ware found coming from other con-temporary production centres do not seem to haveinfluenced, at least not immediately, the local glazeproductions.

Al-Andalus developed its own glaze technologyduring the ninth and tenth centuries. This is indi-cated by the use of high-lead-content and notalkali-based transparent glazes and distinctive vesselshapes and decorative patterns compared to othercontemporary glaze productions. Moreover, the col-our decorations were applied as overglaze for boththe polychrome transparent lead-glazed and opaquetin-glazed wares. This fact rules out, at least in thebeginning, the traditionally proposed link withthe polychrome transparent lead-glazed ware

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produced in Ifriqiya (Tunisia), which was charac-terised by lead-alkaline glazes and underglaze painteddecoration.

When the first technological wave reachedIberia, all the glaze technologies were known in theeastern Islamic world. However, it took anothertwo centuries for the other two waves to arrive.This slow transmission can be explained by the factthat the techniques could only be transmittedthrough specialised potters travelling to new territor-ies. All the raw materials needed for manufacturingthe glaze technologies studied in this paper wereavailable in Iberia, so it was not a problem of supply.At a time when this technology was not yet wide-spread, specialised potters migrated or were attractedto centres of wealth and power, where potential mar-kets could provide a demand for their products.Hence, in the case of the Iberian Peninsula, theywere installed both in seats of power and in seaports. Thus, the reasons seem more economic thanpolitical, although it is true that the Córdoba caliphaltin-glazed ware was used as a means of politicalpropaganda and Seville lustre ware was decoratedwith the name of the Abbadid king.

Regarding the distribution of early glazed warefrom the al-Andalus workshops, there was a limitedregional dissemination, as the majority of the produc-tion was destined for local consumption. The glazedware market was concentrated in the south of Iberiaduring the ninth and tenth centuries. The scarcity of

glazed ware finds in the western (present-dayPortugal) and northern areas coincides with lessIslamised areas (understanding Islamisation as a sub-sequent transformation of social practices) (Carvajal2013). This could be related to the absence of a pre-vious market for sophisticated tableware (evenunglazed ware) that continued at least into thetenth century and the slow adoption of new habitsand trends.

It is still largely unknown what happened in therest of the central and western Mediterraneanregarding the transmission of glaze technology andwhether similar patterns were developed in otherregions. What does seem clear is that the dissemin-ation of medieval glaze technology was also slow inother western Mediterranean regions. In fact, if welook at Christian Europe (excluding the Byzantinearea, which had a different tradition and evolution),glaze technology was incorporated later, from thetwelfth century. Consequently, the study of theearly glaze technological transfers in al-Andalus cancontribute to a better understanding of how medievaltechnological transmissions took place in a broadercontext.

AcknowledgementsThis project has received funding from the EuropeanUnion’s Horizon 2020 Research and InnovationProgramme, Marie Sklodowska-Curie Action (H2020-MSCA-IF-2015, Grant N° 702019).

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