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Deep Eutectic Solvents (DESs) are hygroscopic liquids composed of a hydrogen bond donor (HBD) and acceptor (HBA). Their physical, chemical and electrochemical properties can be tailored to use them as..., info:eu-repo/semantics/published

Deep Eutectic Solvents (DESs) are hygroscopic liquids composed of a hydrogen bond donor (HBD) and acceptor (HBA). Their physical, chemical and electrochemical properties can be tailored to use them as solvents for different applications, i.e. electrodeposition, catalysis, extraction, etc. This can be done by changing the HBD, as well by adding water. However, the interrelated influence of H2O and HBD on the structure of the electrolyte, and on the behavior of the active species is not fully understood. In this work, we select nickel electrodeposition as a case study and we combine electrochemical techniques (cyclic voltammetry, chronoamperometry) with UV-vis spectroscopy and molecular dynamics to understand the influence of water and HBD on the electrochemical behaviour of DESs. The unique combination of these different experimental and modelling techniques provides new insights into the field. The addition of H2O changes, not only the interactions between the constituents of the liquid, but also the coordination of metal cations, which is reflected in the electrochemical performance of different DESs. More importantly, we show that, in the presence of very little (between 0.1 wt% and 2.8 wt%) and high (4.5 wt%) water contents, DESs behave differently, and the changes in their electrochemical behavior are caused by both the complexation of metal cations and the electrolyte transport properties.

Roman glass is studied here by means of optical absorption spectroscopy, in order to provide an objective method to quantitatively evaluate colour. The dataset is composed of 165 soda-lime silicate glass samples from various western European sites, mainly dated from the first to fourth century AD, and containing variable amounts of iron, manganese and/or antimony. Iron redox ratios and colour coordinates (based on the CIELab colour system) are determined and put in relation with the thickness of samples and their manganese/antimony contents. Results reveal thickness as a crucial parameter when discussing glass hues, thus leading to a differentiation between the ‘intrinsic’ and ‘perceived’ colour of glass objects (i.e. the colour of the object with the thickness normalised to 1 mm, and that with its original thickness, respectively). Apart from HIMT and purple glass, the concentration of ferrous iron appears to be correlated with a* — a colourimetric parameter determining how green the glass is. Significant relations of antimony/manganese contents versus iron redox and glass colour are also considered, resulting in quantitative arguments to entitle antimony-decoloured glass as the most oxidised and colourless glass., SCOPUS: ar.j, info:eu-repo/semantics/published

This paper provides the preliminary results from an integrated study of the Hellenistic and early Roman glass vessel assemblage from the large domestic context at Paphos named the House of Orpheus. The homogeneous appearance of the omnipresent slumped and cast vessels in late Hellenistic and early Roman contexts within the entire Mediterranean makes it fairly complex to define the origin of specific assemblages when only studying the external features. We present here the results of a combined study of in-situ optical analysis by means of absorption spectroscopy and chemical analyses with SEM-EDS and LA-ICP-MS. In a first step 107 fragments were optically analysed to categorize possible glass groups and 54 selected pieces were sampled to characterize their chemical composition. Four optically defined glass types can be distinguished with respect to the use of a decolouring or colouring agent and the impact of the furnace condition. The chemical analysis techniques define four distinct subgroups within the homogeneous cluster of Levantine glass.

In the last decades the speciation of the cobalt complex in a glass matrix has been extensively studied. Bivalent cobalt ions in glasses of different composition commonly adopt a tetrahedral coordination, though hexa-or penta-coordinated species are also possible. Changes in the absorbance spectrum of Co-doped glasses were attested in previous studies according to the introduction of different modifying cations. A shifting of the first sub-band characterizing the typical triplets of tetrahedral Co-2 ions in both the visible and near infrared regions was observed, but discrepancies in literature suggested a relevant role of glass composition on the definition of the optical signature,of cobalt. Co-doped glasses with different composition (soda-lime, potash-lime, mixed alkali and ZnO-Na2O-CaO-SiO2) were studied via Fiber Optic Reflectance Spectroscopy (FORS). Pseudo-Voigt functions were used for the deconvolution of the absorbance spectra and the features of the bands characteristic of each cobalt complex were investigated. The structural role played by each modifying cation and the fundamental implications of glass basicity on the speciation of different Co-complexes were stressed. Changes in glass structure resulted in different equilibria between the three absorbing species whose specific optical signatures in the 480-530 nm region interact to determine the resulting absorbance spectrum. (C) 2017 Elsevier B.V. All rights reserved.

Earlier research has shown that several common late antique glass types circulate in Cyprus between the fifth and the seventh century AD, specifically Levantine 1, HLIMT, HIMTa, HIMTb and Egypt 1, HIT, Roman and a plant ash glass. By investigating the glass material from Yeroskipou-Agioi Pente, Maroni-Petrera, and Kalavasos-Kopetra, we aimed to refine the chemical groups present within three late antique Cypriot sites and define the relations between trace elements obtained from LA-ICP-MS. Our data demonstrate compositional patterns that can be exploited to provenance late antique glass by investigating the REE-bearing mineral fractions, the amount of zircon and the carbonaceous fraction of the sand. In addition, Nb and Ti display a strong linear relation which depends on the glass type. Finally, the paper discusses the occurrence of glass recycling on the island and how this activity influenced the concentration levels of specific trace elements. Our study thus sets out an analytical framework to identify recycling events tailored on each compositional type.

Ni coatings were electrodeposited from 1:2 choline chloride (ChCl) - urea (U) deep eutectic solvents (DESs) on low carbon steel. We report on the inter-related influence of water content in the electrolyte and applied potential on the formation of Ni films and their chemical composition and morphology. This was investigated by cyclic voltammetry (CV) and chronoamperometry (CA) in combination with ex-situ characterization techniques (FE-SEM, EDS, XPS and Raman spectroscopy). Ni electrodeposition from DES is shown to be highly complex: Ni+2 reduction is followed by water reduction, which triggers electrolyte decomposition. A water content higher than 4.5%wt and/or performing electrodeposition at potentials more negative than E, info:eu-repo/semantics/published

In this paper we have studied by optical spectroscopy the 5th–7th century glass material from three early Christian sites in Cyprus: Yeroskipou, Maroni Petrera and Kalavasos Kopetra . The glasses could be grouped into six chemical types: Levantine 1, HLIMT, two types of HIMT (named HIMTa and HIMTb), Egypt 1 and HIT. This work presents the first extensive application of in situ absorption spectroscopy to ancient glasses. UV absorption edge, Fe 2 + concentration and colour coordinates are optical parameters that help identifying glass composition because there exists a link between chemical groups and UV–vis–NIR spectral shapes. This allows to select samples for chemical analysis on the basis of diverging optical properties rather than using ad random or subjective naked-eye strategies groups. Furthermore, optical spectroscopy offers an insight into the redox conditions under which the glasses were melted. We also show why the common practice among glass archaeologists to associate certain colour to specific chemical compositions can lead to misinterpretation of the glass consumption.

Production technology of Early Christian (5th–7th centuries AD) wall mosaics, in the eastern Mediterranean and particularly in Cyprus has only recently attracted scholarly attention. Despite the numerous fragments and detached tesserae found in many sites in Cyprus with churches dated to the Early Christian period, it was only now that a more holistic technological study of the materials used for the production of these wall mosaics was initiated. Five sites were chosen for this first study: the seaside basilica of Kourion, the basilica on the acropolis of Amathous, the basilica of area EF2 at Polis-Chrysochous, the basilica of Yeroskipou — Ayioi Pente, and the two basilicas of areas II and V of Kalavasos-Kopetra. Both the glass tesserae and the plasters of the preparatory layers are discussed in this article in order to get a first insight into the technology of Early Christian Cypriot wall mosaics. XRD, DTA-TGA and mercury intrusion porosimetry were employed for the technological and compositional study of the plaster fragments. They were found to be of different compositions depending on the sites of their recovery, and may be made from local materials. Glass tesserae were compositionally characterised with the use of SEM-EDS, Raman spectroscopy, and UV–vis spectrometry. They were found to be made from different raw glass compositions compatible with the early Byzantine period, and opacified with lead stannates and tin oxide. Furthermore, some blue tesserae were found to have been opacified with calcium phosphate, probably coming from bone ash, in accordance with other, recent studies on other early Byzantine glass tesserae. The existence of colour-specific secondary workshops, hypothesised by other studies, seems to be confirmed by the results of this study.

This paper presents the analysis of decoloured and naturally coloured glass from well-dated contexts in the southwest corner of the Roman fort at Oudenburg (Belgium) ranging from the late second to the early fifth century AD. The aim is three-fold. First, provide comparative material in the study of glass consumption from the northwestern provinces of the Roman Empire. Secondly, evaluate possible diachronic shifts in the applied decolourizing agent to produce colourless glass as to assess potential correlations between glass production recipes, provenance and chrono-typology. Finally, provide an added value to the research of glass recycling and mixing in the Roman imperial period. Nine subgroups are distinguished based on their chemical composition determined by LA-ICP-MS: Sb-only, two groups of Mn-only, four groups of mixed Mn-Sb, HIMT and one glass without any decolouring agent. The Sb-decoloured glass is used in the earliest phases and can be attributed to an Egyptian provenance. The two subgroups of Mn-glass likely come from different provenances: one from Egypt and the other later one from the Levant. Most of the glass shows high marks of mixing based on high trace elements concentrations and the simultaneous presence of antimony and manganese. Inhomogeneous mixing of manganese and antimony was also detected through μXRF. One Mn-Sb subgroup likely comes from mixing antimony glass with HIMT. The obtained results help better recognise the shifts in applied glass recipes throughout the Roman imperial period and improve our understanding about the mixing and recycling of glass to supply a Roman military camp., SCOPUS: ar.j, info:eu-repo/semantics/published

The analysis of iron, manganese and antimony in silicate glass is of great interest in chemistry, materials science, earth sciences and archaeological sciences. Yet, conclusions from different fields appear to be contradictory and many questions about redox reactions in glass remain. The purpose of this study is thus to discuss whether and how these multivalent elements interact in glass. Soda-lime silicate melts containing iron along with manganese and/or antimony have been analysed at different high temperatures under argon atmosphere. Using in-situ XANES at the Fe K-edge, redox thermodynamics, kinetics and diffusivities have been assessed for the different compositions. The data obtained show that antimony is more efficient at oxidising iron compared to manganese at all temperatures. The oxidising power trend would thus be Sb > Sb + Mn > Mn. Furthermore, hypotheses on the formation of Fe-Mn complexes are also reported in glasses with stoichiometric proportions of iron and manganese. Based on the determination of redox diffusivities, it appears that presence of other multivalent elements does not significantly affect the iron redox mechanisms and that diffusivity is essentially controlled by the mobility of calcium.

In previous papers, we showed that it is possible to modify the colour of gilding on the silver substrate by applying a surface chemical treatment after it has been burnished [Crabbe et al., Surf. Interface Anal. 2008, 40, 467; Crabbe et al. Applied Physics A, 2013, 111, 39]. These types of techniques are recounted in many medieval and older manuscripts [Crabbe et al., Arch. des Biblio. de Belgique. 2011, 94, 1581]. They have to be taken into account when applying conservation–restoration cleaning to silver gilded statuettes such as the ones from the Holy Lady Shrine from Huy (13th century, Belgium) [Didier et al., Bull. de L'IRPA 1970, 12, 5]. Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM-EDX) and synchrotron X-ray Absorption Spectroscopy (XAS) were carried out both on model and historical samples with the aim of determining if medieval colour treatment has been applied in an efficient way to the silver gilded statuettes of the shrine. Those results are of first importance to the conservator-restorer responsible for the shrine restoration treatment. They will influence the treatment applied to the shrine but also the interpretation of the art-piece, its final aspect and the art-history of medieval times.

Scientific analyses of ancient glasses have been carried out for many years using elemental chemical analysis. However, it is known that the control of the redox conditions in the glass melt has a strong implication on the final hue of glass because it affects Fe2+/SFe. Therefore an increasing number of studies on the redox conditions have been published in recent years by means of synchrotron based Xray absorption spectroscopy. This is a technique which is not easily accessible and requires dedicated facilities. In this paper we describe an alternative approach by means of optical absorption spectroscopy. We synthesised 10 soda-lime-silica glasses with known redox conditions and iron concentration to calibrate the absorption at 1100 nm as a function of Fe2+ concentration. The linear extinction coefficient was also determined. These glasses were also studied by means of X-ray Absorption Near Edge Structure (XANES) spectroscopy. Electron paramagnetic resonance spectroscopy was additionally used as an ancillary method to verify the quality of our data. Furthermore 28 samples from real archaeological samples were analysed by XANES and optical spectroscopy as a case study. The Fe2+/SFe values obtained were compared and demonstrated that the two techniques were in good agreement with each other. Optical spectroscopy can be applied in situ with moderate sample preparation to determine the concentration of Fe2+. To investigate the redox conditions, especially as a first screening approach, this methodology is an important tool to take into consideration before applying more sophisticated techniques such as XANES, which is more elaborate and requires high-tech resources.

The purpose of this paper is to understand why manganese containing Roman glass could be purple or colourless in spite of having very similar chemical compositions. The strategy followed to tackle this question consists in the production of glass with the same chemical composition as Roman glass whereby various production parameters were controlled and systematically analysed. It is shown that redox and colour of glass is more likely to have been managed through internal control through the choice of raw materials and the addition of organic matter. The main difference between ancient and modern glass production relies on the lower melting temperature of Roman furnaces, so that sulphate would have played a less important role in the redox determination., SCOPUS: ar.j, info:eu-repo/semantics/published

In the last decades the speciation of the cobalt complex in a glass matrix has been extensively studied. Bivalent cobalt ions in glasses of different composition commonly adopt a tetrahedral coordination, though hexa- or penta-coordinated species are also possible. Changes in the absorbance spectrum of Co-doped glasses were attested in previous studies according to the introduction of different modifying cations. A shifting of the first sub-band characterizing the typical triplets of tetrahedral Co

Within the field of archeology, textile research is of growing interest because of its potential to provide relevant information regarding either the development or the technological advancement of ancient populations or the socio-economic and religious purposes of textile production. It is of paramount importance in cultural heritage research to use non-destructive techniques. Therefore, dye analyses were performed using two non-destructive methods: time-of-flight secondary ion mass spectrometry (TOF-SIMS) and Fourier transform infrared spectroscopy (FT-IR). In order to build a database, standard samples of dyed silk were prepared using several natural dye compounds; these samples were then analyzed with FT-IR and TOF-SIMS. Afterwards, spectroscopic analyses were carried out on five textile fragments coming from the 16th to the 18th century Korean tombs. FT-IR and TOF-SIMS spectra allowed the identification of fiber of the archeological textiles, making it possible to distinguish between the cotton and silk fibers. Furthermore, it was possible to identify indigo in three blue fabrics and to show its presence in a green textile. The results suggest that FT-IR and TOF-SIMS are two efficient and very helpful techniques for the characterization of excavated fabrics. Copyright © 2011 John Wiley & Sons, Ltd.

The main purpose of this publication is to define sensing parameters by means of optical spectroscopy to study and characterize ancient glass. Because during different times different flux agents were used, a chemical individuation of these elements provides a first dating classification. Normally, X-ray-based chemical methods are applied to this kind of investigation. On the basis of the Ligand-field theory, the absorption band positions of a transition metal ion undergo a change when the ion is placed in different chemical environments. A total of 25 cobalt coloured Roman, post-medieval and industrial glasses were analyzed by means of SEM–energy dispersive X-ray spectroscopy to group them according to their chemical composition. Optical spectroscopy was applied to build a method to study glass with this low-cost and nondestructive technique. It is proved that the cobalt absorption band situated around 535.5 nm for sodium-rich glasses (Roman and industrial material) is shifted towards 526.5 nm for calcium–potassium-rich glasses (post-medieval window glass). This feature was employed as a marker in the case study of the Renaissance window of the Church Wardens from the Church of Our Lady in Bruges, Belgium to distinguish the post-medieval material from the 19th and 20th century restoration material. Copyright # 2011 John Wiley & Sons, Ltd.

The aim of this paper is to highlight the potential of Raman spectroscopy as a fast screening method for large amounts of glass samples. Besides the dedicated research of specific glass collections during the last ten years, a broad corpus of archaeological window glass still needs to be investigated. For many sites, the amount of excavated glass artefacts is enormous and a selection of the most appropriate samples for chemical analysis is necessary. A classification can be made on the basis of the typical Raman signatures for the different kinds of glasses (alkali glass, high-lime low-alkali (HLLA) glass, Pb-rich glass). Even in case of strong fluorescence, an uncomplicated treatment (normalisation) of the measured signals makes it possible to distinguish between the different types of glass. The preliminary screening of glass artefacts with Raman spectroscopy is a useful tool in the study of historical glass and can already answer some questions about provenance, period of production and authenticity of the glass samples. Copyright © 2010 John Wiley & Sons, Ltd.

This paper discusses the composition of the vessel and window glass from three Late Antique Cypriot sites: Yeroskipou, Maroni-Petrera and Kalavasos-Kopetra. Over 170 glass fragments were sampled for quantitative chemical analysis through EPMA measurements. The aim of this work is to establish new insights on the chemical compositions of the glass from Late Antique Cypriot sites to observe the distribution of glass on the island. Furthermore, we compare our dataset with published data of contemporary materials from other regions. Four compositional groups were recognized and correlated to known chemical compositions: Levantine 1, Egypt 1, two types of HIMT glass, HIMTa and HIMTb, while a new group, High Lime Iron Manganese Titanium (HLIMT) has been defined. Glass was supplied to Cypriot glassmakers by both Egyptian and Syro-Palestinian primary producers. Nevertheless, we have observed a specific distribution pattern on the island. In the west, there is about 50:50 ratio between Levantine and Egyptian suppliers. On the contrary, in the central south coast the amount of Egyptian glass drops consistently, in particular in Kalavasos, leaving space to Levantine glass. (C) 2015 Elsevier Ltd. All rights reserved.

We studied the Fe K-edge X-ray absorption near edge (XANES) spectra of several Roman black glass fragments in order to determine the Fe3+/Sigma Fe ratio of these materials. The selected archaeological glass samples cover the period 1st-5th century AD in nine different sites of the North Western provinces of the Roman Empire. The fragments belong to two different compositional groups demonstrating a diachronic evolution: early Roman HMG (High Magnesia Glass) and Roman Imperial LMG (Low Magnesia Glass). The first group contains natural Fe levels (below 2 wt% as Fe2O3), while the LMG has concentrations above 5 wt%. This difference is also reflected by Fe3+/Sigma Fe values. Low iron glass was produced under strongly reducing conditions in order to obtain the black colour, with average Fe3+/Sigma Fe values approximate to 0.17. LMG glass is somewhat more oxidised (Fe3+/Sigma Fe approximate to 0.4-0.5). While HMG glass required active control of the furnace environment, LMG was made under ambient atmosphere and its higher oxidation degree is mainly determined by the chemistry of the raw glass.

Raman spectroscopy is presented as a suitable and fast non-destructive technique to obtain qualitative information about glass samples of various origins (ancient and modern/industrial glass). A first application is the broad corpus of archaeological window glass that still needs to be investigated. For many sites, archaeologists have to deal with large collections of excavated glass samples and a selection of the most appropriate samples for chemical analysis is necessary. A fast classification can be made based on Raman spectra: different kind of glasses (Alkali-glass, High Lime-Low Alkali glass (HLLA)) have their own typical Raman signature. Even for glasses giving strong fluorescence, a classification is possible after a simple treatment of the Raman data. Raman spectroscopy has also been utilized to identify iron containing glasses. The effect of the iron content in glass samples is reflected on the topology of the Raman spectra: a strong link between the ratio of the Q2/Q3 vibration units of the silica tetrahedral structure is seen. Even (semi-) quantitative results can be determined from calibration lines if matrix effects are taken into account (similar glasses). In amber colored glasses, an extra peak ~415cm-1 in the Raman spectra indicates the presence of a Fe-S chromophore. Finally, in the fluorescent signals of some yellow and red glasses two peaks of Zn-Se-Cd-S nanocrystals have been identified.

Absorption spectroscopy is the technique that measures the absorption of radiation as a function of wavelength, due to its interaction with the material. During a research project funded by our home university, we were able to investigate the possibilities of this technique to study ancient glasses. One of our main conclusions is that UV-VIS-NIR absorption spectroscopy is especially suited to characterize colored artifacts in terms of composition and furnace conditions. Moreover, for naturally colored window glasses, we have shown that this technique allows us to classify fragments based on differences in iron impurity levels. It is a semi-quantitative analysis tool that can be applied for a first-line analysis of (large) glass collections. Thanks to the commercial available portable instruments, these measurements can be performed at relative high speed and this in-situ if necessary. To illustrate the possibilities of this technique, we describe in this paper two case-studies. In a first test-case we analyze 63 naturally colored window glasses and demonstrate how groups with different iron concentrations can be identified by calculating the absorption edge position from the measured optical spectrum. In a second case-study 8 modern naturally colored and 31 intentionally colored Roman glass fragments are the point of focus. For these samples we first estimate which samples are potentially fabricated under the same furnace conditions. This is done based on the calculated color values. Finally we identify the type of applied colorants.

In this paper we studied the transmittance spectra of a collection of several glass samples taken from a 16th century stained window of the Church of Our Lady in Bruges, Belgium. We recorded the optical spectra for all the samples in the region between 350 and 1600 nm. The goal of our research was to reveal information about the composition of the glass artifacts in a fast and non-destructive way. Analysis of the optical spectra allowed us in the first place to identify the type of colorants that were used. It was possible to recognize metal ions, such as Fe 2+ , Fe 3+ , Co 2+ , Mn 3+ , Cr 3+ and Cu 2+ . Also colors made of metal nanoparticles, such as silver and copper colloids were successfully identified. The recognition of the coloring agents is of particular interest in dating the glass pieces. This is because some colorants were only used in certain periods. Green glass colored by chromium was produced only after the mid 19th century onwards. Our study showed that 3 of the 10 pieces were colored by this element and they originate as such from a later period. A second conclusion refers to the applied fluxing agent. By analyzing the spectral position of the first cobalt absorption band, we were able to classify the glass pieces as potash based (used in medieval times) or soda-based (used in modern times) and therefore to classify them as original or as restoration material. From the 10 blue colored samples, 7 of them were recognized as original material. Finally, for the naturally colored parts the analysis of the spectra allowed us to group them based on cobalt impurities.

In this publication optical spectroscopy is considered to be a supplementary technique to study ancient colored glass. It results from a systematic study of th e UV-VIS-NIR transmission spectra of in tentionally colored glass fragments from various archaeological and historical sites and dated from the Roman period to the 21 th century AD. The main goal consists of defining optical sensing parameters for this type of material. The considered colorants are iron, cobalt, manganese, copper and chromium. It is proved that many cases exist wher e optical spectroscopy can be seen as a st raightforward, non-destructive, low-cost and in-situ applicable technique in identifying authentic material or to obtain information about the origin of the material. Possible sensing parameters are defined as the absence/pres ence of absorption bands charact eristic for a specific coloring metal oxide and the spectral position of these bands. These parameters could reveal information about the applied furnace conditions and/or to the composition of the glass matrix. It is shown that the cobalt absorption band situated around 535 nm for soda rich glasses (Roman and industrial times) is shifted towards 526 nm for potash rich glasses (medieval and post-medieval times). Keywords: optical spectroscopy, color, glass, non -destructive testing, chemical analysis, history

Window glass fragments from four Belgian sites were studied and for a set of eighty-five samples the UV-VIS-NIR transmission spectra were analyzed. This collection contains historical and archaeological finds originating from religious buildings namely the Basilica of Our Lady of Hanswijk in Mechelen (17th-20thc) and the Church of Our Lady in Bruges (16th-20thc) as well as from secular buildings as a private house/Antwerp (18th-1948) and the castle of Middelburg-in-Flanders (1448-17thc). All sites contain material on the hinge point between the medieval and the industrial tradition. The variation in composition of the analyzed samples can be explained by the use of different glassmaking recipes, more specifically the use of different raw materials. The composition of window glass differs essentially in the type of flux, using a potash rich fluxing agent until the post-medieval times and industrial soda from the 19th century onwards. A second difference concerns the iron impurities in the glass. For all fragments a clear compositional classification could be made based on the iron concentration. These conclusions were based on archaeological research and drawn after submitting samples to expensive, complex, time-consuming and destructive chemical analyzing methods. Our study indicates that similar conclusions could be made applying the proposed optical based methodology for plain window glass. As a whole, the obtained results make it possible to cluster the fragments for a particular site based on three different sensing parameters: the UV absorption edge, the color and the presence of characteristic absorption bands. This information helps in identifying trends to date window glass collections and indicating the use of different raw materials, production technologies and/or provenance.

In this paper we have studied by optical spectroscopy the 5th–7th century glass material from three early Christian sites in Cyprus: Yeroskipou, Maroni Petrera and Kalavasos Kopetra. The glasses could be grouped into six chemical types: Levantine 1, HLIMT, two types of HIMT (named HIMTa and HIMTb), Egypt 1 and HIT. This work presents the first extensive application of in situ absorption spectroscopy to ancient glasses. UV absorption edge, Fe2 + concentration and colour coordinates are optical parameters that help identifying glass composition because there exists a link between chemical groups and UV–vis–NIR spectral shapes. This allows to select samples for chemical analysis on the basis of diverging optical properties rather than using ad random or subjective naked-eye strategies groups. Furthermore, optical spectroscopy offers an insight into the redox conditions under which the glasses were melted. We also show why the common practice among glass archaeologists to associate certain colour to specific chemical compositions can lead to misinterpretation of the glass consumption.