Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass Tesserae
Calcium antimonate (in the hexagonal or cubic form) dispersed in the glass matrix is an artificially synthesized phase commonly documented as opacifier for white glasses during the Roman period. Glasses of this type occasionally contain variable amounts of lead oxide. There is no consensus about the...
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MDPI AG
2020-06-01
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| Online Access: | https://www.mdpi.com/2571-9408/3/2/32 |
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| author | Cristina Boschetti Cristina Leonelli Roberto Rosa Marcello Romagnoli Miguel Ángel Valero Tévar Nadine Schibille |
| author_facet | Cristina Boschetti Cristina Leonelli Roberto Rosa Marcello Romagnoli Miguel Ángel Valero Tévar Nadine Schibille |
| author_sort | Cristina Boschetti |
| collection | DOAJ |
| description | Calcium antimonate (in the hexagonal or cubic form) dispersed in the glass matrix is an artificially synthesized phase commonly documented as opacifier for white glasses during the Roman period. Glasses of this type occasionally contain variable amounts of lead oxide. There is no consensus about the origin and role of the lead component in white glasses, whether it was functional to modify the workability of the glass and/or to help the precipitation of the particles, or whether it was an unintentional pollutant introduced with the raw materials. A group of lead and lead-free white mosaic tesserae from the fourth-century CE villa of Noheda in Spain were analyzed by differential scanning calorimetry (DSC) and high temperature X-ray diffraction (HTXRD) to evaluate the impact of variable amounts of lead oxide in the precipitation of calcium antimonate on the viscosity of the glass. The analyzed glasses show thermal events that have been related to the composition of the glass via multicomponent linear regression model. CaSb<sub>2</sub>O<sub>6</sub> and Ca<sub>2</sub>Sb<sub>2</sub>O<sub>7</sub> formed in the glass during the cooling phase and the glass was not reheated. Lead oxide influences the thermal behavior of the glass, lowering the onset temperatures of all the events, implying a more cost-effective production process. We propose that lead was added intentionally or that lead-bearing raw materials were selected specifically by the ancient glass artisans. |
| first_indexed | 2024-03-10T18:51:18Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 2571-9408 |
| language | English |
| last_indexed | 2024-03-10T18:51:18Z |
| publishDate | 2020-06-01 |
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| record_format | Article |
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| spelling | doaj.art-59207f9a4ab9449e87e78249de6505cd2023-11-20T05:04:44ZengMDPI AGHeritage2571-94082020-06-013254956010.3390/heritage3020032Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass TesseraeCristina Boschetti0Cristina Leonelli1Roberto Rosa2Marcello Romagnoli3Miguel Ángel Valero Tévar4Nadine Schibille5IRAMAT-CEB, UMR5060, CNRS/Université d’Orléans, 3D rue de la Férollerie, CS 60061, 45071 Orléans CEDEX 2, FranceDipartimento di Ingegneria “Enzo Ferrari”, Università degli Studi di Modena e Reggio Emilia, Via Pietro Vivarelli 10, 41125 Modena, ItalyDipartimento di Ingegneria “Enzo Ferrari”, Università degli Studi di Modena e Reggio Emilia, Via Pietro Vivarelli 10, 41125 Modena, ItalyDipartimento di Ingegneria “Enzo Ferrari”, Università degli Studi di Modena e Reggio Emilia, Via Pietro Vivarelli 10, 41125 Modena, ItalyDepartamento de Historia Antigua, Facultad de Humanidades y Ciencias de la Educación, Universidad de Castilla-La Mancha, Av. de los Altares s/n, 16071 Cuenca, SpainIRAMAT-CEB, UMR5060, CNRS/Université d’Orléans, 3D rue de la Férollerie, CS 60061, 45071 Orléans CEDEX 2, FranceCalcium antimonate (in the hexagonal or cubic form) dispersed in the glass matrix is an artificially synthesized phase commonly documented as opacifier for white glasses during the Roman period. Glasses of this type occasionally contain variable amounts of lead oxide. There is no consensus about the origin and role of the lead component in white glasses, whether it was functional to modify the workability of the glass and/or to help the precipitation of the particles, or whether it was an unintentional pollutant introduced with the raw materials. A group of lead and lead-free white mosaic tesserae from the fourth-century CE villa of Noheda in Spain were analyzed by differential scanning calorimetry (DSC) and high temperature X-ray diffraction (HTXRD) to evaluate the impact of variable amounts of lead oxide in the precipitation of calcium antimonate on the viscosity of the glass. The analyzed glasses show thermal events that have been related to the composition of the glass via multicomponent linear regression model. CaSb<sub>2</sub>O<sub>6</sub> and Ca<sub>2</sub>Sb<sub>2</sub>O<sub>7</sub> formed in the glass during the cooling phase and the glass was not reheated. Lead oxide influences the thermal behavior of the glass, lowering the onset temperatures of all the events, implying a more cost-effective production process. We propose that lead was added intentionally or that lead-bearing raw materials were selected specifically by the ancient glass artisans.https://www.mdpi.com/2571-9408/3/2/32calcium antimonateRoman glass technologyglass opacificationDSChigh temperature XRD |
| spellingShingle | Cristina Boschetti Cristina Leonelli Roberto Rosa Marcello Romagnoli Miguel Ángel Valero Tévar Nadine Schibille Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass Tesserae Heritage calcium antimonate Roman glass technology glass opacification DSC high temperature XRD |
| title | Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass Tesserae |
| title_full | Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass Tesserae |
| title_fullStr | Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass Tesserae |
| title_full_unstemmed | Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass Tesserae |
| title_short | Preliminary Thermal Investigations of Calcium Antimonate Opacified White Glass Tesserae |
| title_sort | preliminary thermal investigations of calcium antimonate opacified white glass tesserae |
| topic | calcium antimonate Roman glass technology glass opacification DSC high temperature XRD |
| url | https://www.mdpi.com/2571-9408/3/2/32 |
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