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Roman glass is well studied and known to have been produced from a mineral soda source and calcareous sand with variation between elements relating to naturally occurring minerals in the sands. While the common characteristics of colourants and opacifiers used in opaque and translucent glasses are well understood, the diverse elemental composition of colouring agents associated with the highly specialised, and largely unexplored, technique of enamel-painted glass has never been firmly established. There remains a significant gap in knowledge of pigments used for this technological innovation which is here addressed through the deployment of non-invasive portable X-Ray Flourescence (pXRF) analysis and microphotography on a unique Roman enamel-painted gladiator glass from Vindolanda fort. This vanguard research has successfully established, for the first time, a palette of pigments associated with this specialist technique. It is now possible to unravel previously unknown information on complex manufacturing processes and significantly expand the repertoire of the pigments bound up in enamelling recipes used to depict the striking iconographic scenes on the Vindolanda vessel and, potentially, other Roman enamelled glassware. The detection of Cinnabar, Egyptian blue, Orpiment and other pigments are ground-breaking discoveries that will have a transformative impact on early glassmaking studies and push the boundaries of scholarship into new directions of analytical approaches in heritage materials science to complement recent success in this field with Raman spectroscopy and other techniques. The methodology is unprecedented and has been validated through the high quality of the resulting data which permits the extrapolation of elemental compositions of enamelling materials from those associated with the base vessel. This unique approach provides remarkable insights that will revolutionise our understanding of enamelling technologies using the Vindolanda vessel as the investigative platform for forgotten practice.

The Antonine Wall was commissioned by the Roman Emperor Antoninus Pius around 142 CE and stretches for c. 60 km across the central belt of Scotland, marking the Empire’s most north-western frontier. This vanguard research reports on the materials referred to by Antiquarian sources as having been applied during the sixteenth century for the redecoration of an iconic Distance Sculpture that was once embedded into the mural barrier. Portable non-invasive technologies, including pXRF and in-situ microphotography were deployed. These techniques were further supplemented by micro-sampling for SEM/EDS, FTIR–ATR and microscopy of embedded cross-sections. The validity of applying these complementary techniques has been confirmed. They provide a comprehensive account of the polychromy present, including pigments that could have been applied during the Roman period and others that were only available from the fifteenth or sixteenth Centuries. The work has confirmed stratigraphic sequencing of the pigments which will, in due course, permit the digital reconstruction of how this Classical relief sculpture would have been adorned during the Renaissance.

Non-destructive analytical techniques are now widely and successfully employed in the fields of materials science and conservation. Portable X-ray fluorescence (pXRF) and portable Raman spectrometry have proven particularly valuable for the rapid in-situ analysis of samples, but their applicability for the analysis of archaeological artefacts for which survival of surface treatments can be negatively impacted by post-depositional processes has been underexplored. Roman relief-sculpted monumental inscriptions from the Antonine Wall, commonly referred to as ‘Distance Slabs’, have offered an excellent opportunity to deploy these non-destructive techniques to determine whether they were originally adorned with pigments and, if so, to identify the colours used. This is a revolutionary approach to identifying colours on ancient sandstone sculpture that transforms our understanding of these unique monuments. Elemental composition analysis by pXRF has confirmed evidence for pigments and this is supported by the Raman results, making it possible to develop and reconstruct a palette of colours that originally brought these monuments to life in vibrant polychrome. The research offers a new methodology for identifying pigments on sandstone sculpture and opens new avenues for investigating other classes of material culture alongside the development of bespoke analytical equipment.

This paper explores new approaches to epigraphic evidence from the Antonine Wall that, in some respects, depart significantly from perceived wisdom. Addressing the inscriptions from alternative perspectives and incorporating attribute analysis, material mapping and a review of historical sources has revealed previously unexplored dimensions to a significant category of inscriptions here referred to as Distance Stones. The results cast new light onto these enigmatic ancient artefacts, exposing potential inconsistencies relating to units of measure and challenging hypotheses that have endured for more than two centuries. Critical review has uncovered patterns of difference and similarities that alter our perception of these unique frontier sculptures and lend credence to the proposal that they may have originally been placed, not along the Wall as has been traditionally accepted, but along the Military Way where passers-by could more meaningfully engage with them.