Composition and state of alteration of 18th-century glass finds found at the Cistercian nunnery of Clairefontaine, Belgium K. Hellemans a, * , A. Vincke a , S. Cagno a, b , D. Herremans c , W. De Clercq b , K. Janssens a a Antwerp X-ray Instrumentation and Imaging Laboratory, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium b Centre of Excellence for Environmental Radioactivity (CERAD), Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway c Historical Archaeology Research Group (HARG), Department of Archaeology, Ghent University, Sint-Pietersnieuwstraat 35, B-9000 Ghent, Belgium article info Article history: Received 17 July 2013 Received in revised form 11 March 2014 Accepted 29 March 2014 Available online xxx Keywords: 18th-century glass LA-ICP-MS SEM-EDX Quantitative analysis Glass alteration abstract A hundred 18th-century glass fragments were recovered at the Clairefontaine monastery in the Belgian province of Luxembourg. They were analysed by a combination of SEM-EDX and LA-ICP-MS in order to determine their major composition as well as their trace element signature. Multivariate statistical methods such as hierarchical clustering and principal component analysis were used to divide the glass fragments into four main groups: potassium-rich glass, sodium-rich glass, potassium/lime-rich glass and high-lime-low-alkali glass. Within every group, not only a similarity in composition is observed, but also in colour, morphology and deterioration patterns. Potash glass fragments are the most abundant and show extensive deterioration; two classes of potash glass were identified: one similar to certain Central European glass compositions, while the other one, characterised by large variations in potash: lime ratio, may be attributed to local (regional) glass production. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction 1.1. Aim and context Archaeological excavations at the Cistercian nunnery of Clair- efontaine, Belgium have revealed an assemblage of 18th-century glass vessels. These were mainly utilitarian objects used for storage, drinking or dining. The assemblage is dominated by storage bottles of various kinds and by conical beakers, a particular type of 18th- century drinking ware. A set of 100 glass samples from Clair- efontaine was analysed by means of two techniques: scanning electron microscopy with energy dispersive X-ray analysis (SEM- EDX, for obtaining the major and minor element composition) and laser ablation inductively coupled mass spectrometry (LA-ICP-MS, for trace element determination). The aim of the study is twofold. First of all, the compositional analyses are used to provide insight in the chemical composition of the glass finds; they provide information on a period of (vessel glass) history not extensively studied up to now. The results are compared with the glass compositions found in England and Cen- tral Europe in the same period (Ashurst, 1970). Secondly, in view of the fact that a large part of the glass assemblage consists of non- durable glass, the compositional results have been used to assess whether the different alteration states of the glass are related to technological variation/evolution or to post-depositional processes. 1.1.1. The dawn of industrial glass The study of 18th-century glass from archaeological contexts is still in an early stage. On the basis of mainly visual aspects such as shape and decoration, 18th-century vessel glass in the Low Coun- tries may be classified as either ‘Bohemian’, English’ or ‘local’ products, yet this has proven to be a rather subjective approach (Henkes and Laan, 1986). In fact, unlike for the study of 16th and 17th-century vessel glass (e.g., Janssens et al., 1998), only seldom the chemical composition of 18th-century finds are taken in ac- count (Van der Linden et al., 2005). In the course of the 17e18th century, the historical context to which these glass finds belong, witnessed several technological innovations in the European glass industry. At the beginning of the 17th century, English glassmakers started to fire their ovens with coal. Higher and more stable temperatures could be ob- tained which allowed them to produce high quality products on a larger scale. Examples are the large and robust wine bottles in coloured potash glass that were exported to Europe and North America (Jones, 2010). As a general trend, glassmakers settled near/in towns and urban centres (Henkes, 1994). New recipes for * Corresponding author. E-mail address: kevin.hellemans@uantwerpen.be (K. Hellemans). Contents lists available at ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas http://dx.doi.org/10.1016/j.jas.2014.03.039 0305-4403/Ó 2014 Elsevier Ltd. All rights reserved. Journal of Archaeological Science 47 (2014) 121e133