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The materials, painting techniques and conservation state of the enamelled stain glass of the Catalan Modernist workshops operating in Barcelona are studied. It is known for its creativity and artistic value where textured, flashed, coloured and enamelled glasses concur. In the late 19th century, Catalan workshops used a new type of ready-to-be-used enamels (lead-zinc borosilicate glass) incorporating pigment particles and colourants. Although humidity, pollutants and solar irradiation are the main causes of corrosion, the microstructure of the enamels plays a role- Enamels that contain large particles close to the surface appear more corroded than those that are fully amorphous. Lixiviation of lead, boron and zinc produced a hydrated layered silica rich fragile glass and the subsequent precipitation of lead, sodium and calcium compounds on the surface, cracks around particles and inside the bubbles decrease the chemical and mechanical stability. The practices of some workshops produced enamels with reduced stability. [ABSTRACT FROM AUTHOR]

Portus Ilicitanus (Picola, Alicante) was the main sea harbour of the Roman Colonia Iulia Ilici Augusta and as such played a crucial role in the supply of fundamental commodities to the Iberian Peninsula. Excavations yielded large quantities of glass in fourth‐ and early fifth‐century contexts. Elemental analysis of 60 samples by laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) confirmed that the glasses were imported from the Eastern Mediterranean. A majority of the glasses correspond to the HIMTa primary production group, which originates from Egypt. The statistical evaluation of published data of 589 HIMT glasses further revealed differential distribution patterns of the HIMTa and HIMTb subtypes between the Eastern and Western Mediterranean, suggesting chronological trends that are linked to wider geopolitical changes. This demonstrates the need for systematic large‐scale approaches to identify supply patterns and possible factors underlying geographical differences and/or chronological developments. [ABSTRACT FROM AUTHOR]

Forty-seven window and vessel glasses from the 'Great Temple' at Petra (Jordan), dating to the first/second and fourth centuries ce, were analysed by EPMA for major and minor elements. A subset of 29 samples from Petra and 15 samples from Khirbet et-Tannur were additionally analysed for trace elements, using LA-ICP-MS. Six compositional groups were identified on the basis of the presence of decolouring agents. The majority of the glasses derive ultimately from the Levantine coast, but most of the groups show evidence for highly selective recycling. The observed differences between the two sites could be related to different chronological ranges, functions, relative wealth and trade connections. [ABSTRACT FROM AUTHOR]

Fifth- to seventh-century window glass fragments from the Petra Church in Jordan were analysed by EPMA and spectrophotometry to characterize their optical properties and chemical composition. The objective of this study was to determine the provenance of the raw glass and the secondary production procedures of the window-panes. Judging from the material evidence, both the crown window-panes and possibly the rectangular samples were produced through glass-blowing techniques. The chemical data show that the assemblage forms a homogeneous group of soda–lime–silica glass of the Levantine I type. The green glass, however, has higher silica and lower soda contents than the aqua-blue fragments. The composition of one sample suggested the recycling of Roman glass. Our results confirm the trade of glass between the Levantine coast and Petra during Late Antiquity. No colouring agents other than iron were detected. Spectrophotometry confirmed the presence of iron and showed that the window fragments absorbed light relatively equally across the visible part of the spectrum. The windows thus seem to have provided an almost colourless illumination for the sacred interior. [ABSTRACT FROM AUTHOR]

Previous research has shown that Iznik glazes are characterized by low potash and magnesia contents. It was therefore suggested that the flux used was either a purified plant ash or some unidentified mineral source of soda. More recently, as a result of the detection of small, but significant, amounts of boron and lithium in Byzantine glasses from western Turkey, which also exhibit low potash and magnesia contents, it has been suggested that the source of the flux used was a soda-rich evaporite associated in some way with the extensive borax deposits in the region. LA-ICP-MS has been used to establish that Iznik glazes also contain similarly small amounts of boron and lithium. The Na/K, Na/Mg, Na/Ca and Na/B ratios for these Iznik glazes are shown to be comparable to the equivalent ratios calculated from published data for waters from a range of Na-HCO3 type hot springs in western Turkey, with the closest match being to the hot springs around Afyon- Gazligöl, which is consistent with documentary evidence. It is therefore proposed that the soda-rich salts produced by evaporating water from these springs to dryness would have provided the flux required for the production of Iznik glazes and high-boron Byzantine glasses. [ABSTRACT FROM AUTHOR]

We present compositional data for nearly 100 glass samples from Pergamon, western Turkey, spanning 1500 years from the Hellenistic to Late Byzantine and Islamic periods. The data shows the use of already-known Roman glass groups during the first half of the time frame, for imported vessels as well as locally worked glass. No compositional change is seen related to the introduction of glass blowing for either of the glass groups in use during this time. During the first half of the 1st millennium AD, two previously little-known boron- and alumina-rich compositional groups emerge. These glass groups, thought to be regionally produced, dominate glass compositions in Pergamon during the mid-to late Byzantine and Islamic periods, indicating a major shift in glass supply and a fragmentation of the economy into more regional units. Plant-ash glass, from the 9th century AD replacing mineral natron glass in the Levant, plays only a minor role in Byzantine and Islamic Pergamon. [ABSTRACT FROM AUTHOR]

Laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS) analyses of loose glass tesserae from the Northwest Quarter of Gerasa/Jerash has enhanced our understanding of the dynamics regulating the production and circulation of glass tesserae in second‐ to eighth‐centuries ce Jordan and the diachronic development of mosaics at the site. The identification of Levantine and Egyptian compositions (Roman‐Mn, Levantine I, HIMT, Foy 2.1) proves the continuous production of mosaics from the second to the seventh centuries. The Levantine I tesserae were made by the recycling and colouring of glass cullet. The gilded tesserae, in contrast, were all of an Egyptian base glass, likely illustrating the import of finished tesserae. [ABSTRACT FROM AUTHOR]