## 3 Results and Discussion  
### Understanding Archaeological Context: The First Step toward a Tailored Selection of Materials  
The most recurring questions related to the study of archaeological materials are aimed at understanding whether a local production can be identified. This issue is of a particular relevance for glass, where the very sporadic occurrence of furnace remains makes it extremely challenging to map the production sites and distinguish them from the working sites. If the context where materials have been unearthed shows evidence of a production/working activity of glass (i.e., furnace remains, production waste, and tools), the selection of the assemblage to be investigated is generally aimed to characterise all these indicators. Therefore, the choice to carry out archaeometric analyses on materials that can be typologically heterogeneous (such as production indicators, scraps, and finished objects) is justified by the need to identify raw materials used in glassmaking. An example is, in this regard, the ancient port of Classe (Ravenna, Italy), one of the most important trade centres between the 5 th and 8 th centuries CE in the Northern Adriatic area. Archaeological excavations identified the main context for glassworking inside one of the warehouses built at the beginning of the 5 th century CE, where a small circular kiln had been unearthed; around the kiln, a massive amount of glass fragments and glassworking waste (973 finds) was brought to light in 2001 ([PERSON], 2012). Results from archaeometric analyses demonstrated that, in the 5 th century CE, the secondary glass workshop in Classe was dedicated to the shaping of vessels starting from raw glass chunks and, possibly, cullets. Evidence of glass remelting and glassblowing were found, while no evidence of primary production was uncovered ([PERSON], 2012). Moreover, comparisons between Classe and Aquileia, the two most important Late Antique archaeological sites of Northeastern Italy, were undertaken to shed light on the role of the Northern Adriatic area in glass production, trade, and consumption. The comparison showed that, unlike Classe, correlations did not exist in Aquileia between specific types of objects and the compositions of glass; this data has further strengthened the hypothesis of a local shaping of specific objects at Classe (2012). An analogous approach in the selection of materials to be studied can be applied to caragos from shipwrecks. The case of the wreck of the Iulia Felix ship, which sank in the 2 nd century CE off the coast of Grado (Friuli-Venezia Giulia, Italy) is, in this sense, thorough. The archaeological and archaeometric study of the assemblage of glass materials was performed on cullets and finished objects to achieve data on colourless and coloured Roman glass production technology. The strong evidence of compositional variability among the Iulia Felix assemblage strengthened the hypothesis of a dispersed production model for Roman glassware and the common practice of recycling in Roman ages, especially for daily-use vessels ([PERSON], 2012; [PERSON], 2012). If archaeological glass is found at multilayered contexts and/or where there is no univocal evidence of local production, the approach to the selection of materials to be studied needs to be different. Multilayered contexts are particularly challenging to be approached: inhabited for more or less extended periods, they generally are urban, monastic, and/or residential sites, where structures that can be interpreted as small kilns, though without sound evidence of glass production (i.e., no production/processing indicators recovered), can also be found. When these contexts are faced, an archaeometric study of numerically consistent sets of fragments (without paying due attention to the multilayered structure of the site and often comparing data obtained from the analysis of fragments pertaining to different objects and chronological frames) can rarely result in a meaningful and exhaustive scenario.