Analysing the Physicochemical Characteristics of an Archaeological Glass Collection from Mexico City, Mexico

Research article Intervención ISSN 2448-5934 ENERO-JUNIO 2024 JANUARY-JUNE 2024 OJS Analysing the Physicochemical Characteristics of an Archaeological Glass Collection from Mexico City, Mexico Ir a la versión en español DOI: 10.30763/Intervencion.293.v1n29.72.2024 • YEAR 15, NO. 29: 42-64 Índice / Contents Submitted: 27.09.2023 • Accepted: 04.03.2024 • Published: 31.07.2024 José Roberto Peralta Rodríguez Arturo García Bórquez Escuela Superior de Medicina-Sección de Escuela Superior de Física y Matemáticas, Estudios de Posgrado e Investigación, Instituto Politécnico Nacional (ipn), Mexico Instituto Politécnico Nacional (ipn), Mexico orcid: orcid: https://orcid.org/0000-0002-2568-5996 https://orcid.org/0000-0001-7422-577X María de Jesús Alvizar Rodríguez Museo del Templo Mayor (mtm), Instituto Nacional de Antropología e Historia (inah), Mexico | orcid: https://orcid.org/0009-0005-4551-6654 Translation by Richard Addison ABSTRACT This paper is a preliminary study detailing the results of a chemical-physical analysis executed on 20 fragments of archaeological glass from Mexico City. The analysis was carried out using a scanning electron microscopy (sem) and X-ray microanalysis, two techniques not previously applied in Mexico for this purpose. Both the content of oxides and the sample’s physical characteristics allowed us to determine that approximately seventeen coincided with the types of components identified in European glass prior to the 18th century. The other three were identified as having come from a later period. The physical characteristics on the microscopic level were diverse and showed adhesions resulting from the effects of environmental degradation. This facilitates an analysis of oxide content and mechanisms of glass degradation that will allow us to further our understanding of this material’s production process in our country moving forward. KEYWORDS archeometry, barrilla, tequesquite, glaziers, vitrifiers, fluxes, leaching 42 CONVOCATORIA 2024 CALL FOR PAPERS 2024 Research article Intervención ISSN 2448-5934 ENERO-JUNIO 2024 JANUARY-JUNE 2024 OJS Índice / Contents INTRODUCTION exico City, the New Spanish capital, quickly established itself as an important political and economic center in which much of the country’s population came to reside, increasing the demand for a variety of products, including glass, initially of sumptuary type. Between 1530 and 1534, the first glaziers arrived in New Spain; so by the end of the 16th century at least eight of them were working in the country, leading to the creation of two ordinances enacted to regulate the use of raw materials. In the 17th and 18th centuries, the number of artisans increased (Peralta, 2011, pp. 34-72; 2014, pp. 73-78). The existence of these and the identification, through the recognition of written and pictorial testimonies, of furnaces in production sites are evidence of the local manufacture of glass. They made flat glass stills, sublimators, mortars, flasks, vessels with particular characteristics, antlers, candlesticks with mirrors, chandeliers, glass beads, eyeglasses and other objects of sumptuary use, at the request of apothecaries, metal separators and, in general, society as a whole (Peralta, 2011, pp. 34-72; 2013, [23], pp. 2-25; 2014, pp. 73-78). Production persisted despite the instability of the country during the independence movement, resulting in the establishment of approximately seven manufacturing centers within Mexico City’s perimeter by the 19th century. Their products were highly sought after by the food and beverage industries, professionals, and the general populace. Between the 16th and 19th centuries, goods made from this material came from Spain, the Czech Republic, France, England, and what today is the United States (Peralta, 2011, pp. 34-72; 2021, pp. 5-14). From the outset, glass production was driven by the needs of human beings, as well as its aesthetic qualities, and the raw material’s geographical availability (the latter two determined its manufacture and if the process of elaboration was to be kept secret, due to the sumptuary value given to the objects). The Industrial Revolution and the resulting advancements in scientific knowledge made it possible to interpret the interaction of the chemical compounds that integrated the glass material, which led to the production process being significantly modified. Even today, we see that industries seek to protect certain aspects of their specific production methods (Alvizar, 2007, pp. 38-46; Peralta, 2018, pp. 3-29). In Mexico City, the legacy of glass production was left by the Iberian artisans, with everything suggesting that Mexico employed similar methods of manufacturing, since currently there is no written documentation, formula, or exact recipe for the proportions of M Analysing the Physicochemical Characteristics of an Archaeological Glass Collection from Mexico City, Mexico CONVOCATORIA 2024 CALL FOR PAPERS 2024 43 Research article Intervención ISSN 2448-5934 ENERO-JUNIO 2024 JANUARY-JUNE 2024 OJS Índice / Contents the raw material’s components used in the pre- and post-colonial era. On the other hand, the investigation of urban glass objects thus far has been conducted from the standpoint of the aesthetic characteristics of complete pieces, which are compared to those of European origin in order to locate them in a specific period of time. However, the physicochemical analysis of fragments and unconnected pieces of this material recovered in archaeological preservation efforts may prove advantageous in determining their historical context. It is currently possible to chemically analyze all types of archaeological material through various methodologies to identify the molecular components that constitute them, with which the raw material used can be recognized which, in turn, contributes to the understanding of the manufacturing processes and the evolution of its production (Cadena, 2018, pp. 28-32; Cárdenas, 2020, pp. 70-72). Since little has been developed here in Mexico—and, even more scarcely, from the perspective of a proper chemical analysis—the manufacture of glass, this work aims to perform a preliminary ana lysis of the composition of oxides and the microscopic state of archaeological glass fragments. This, in conjunction with the review and observation of macroscopic physical characteristics, facilitates the determination of the period of production, whether colonial or post-colonial. The proposed objectives are: 1) First, to recognize in archaeological glass fragments located in two areas of the Historic Center of Mexico City the compos ition of vitrifying, silicon (SiO2), and phosphoric (P2O5) oxides; fluxes such as sodium (Na2O) and potassium (K2O) oxide; stabilizers such as calcium oxide (CaO), magnesium oxide (MgO) and aluminium oxide (Al2O3); coloring agents such as iron oxide (Fe2O3); and decolorizing agents such as manganese oxide (MnO) by (...truncated)