Nanotechnology in Roman Opaque Red Glass from the 2nd Century AD. Archaeometric Investigation in Red Sectilia from the Decoration of the Lucius Verus Villa in Rome

Abstract

This work aims to characterise the chemical composition of Roman opaque red glass sectilia dated to the 2nd century A.D and to shed light on Roman glassmaking production of different shades of red, from red to reddish-brown. Due to the lack of technical historical sources for this period many questions about technological aspects still remain. In this project a multi-disciplinary approach is in progress to investigate the red glass sectilia with several red hues from the Imperial Villa of Lucius Verus (161–169 A.D.) in Rome. First, colorimetric measurements were taken to identify the various red hues. The second step was chemical characterization of the samples and the identification of crystalline colouring phases. Particle Induced X-Ray Emission (PIXE) analysis was used to investigate the chemical composition of these glass samples, while the crystalline phases were identified by Raman Spectroscopy and Scanning Electrons Microscope with Energy Dispersive X-ray Spectrometry (SEM-EDS). Using SEM-EDS nanoparticles were detected as a colouring agent, the chemical composition and the morphology of which has been studied in depth. This information has been compared with the colorimetric analysis to establish any correlation with the different colour hues.

The Technology of Copper-Based Red Glass Sectilia from the 2nd Century AD Lucius Verus Villa in Rome

“…Although this new opaque red glass, called red brown, is indicated as being duller than sealing wax, several red hues are included under this designation. It was recently verified that no marked visual differences were observed among Roman red brown and sealing wax [29]. Furthermore, it was established that sub-micrometric particles of metallic copper, varying between 60 and 400 nm, generate colour and opacity in the red brown glass [12,30].…”

“…This work aimed to characterize the different red glass hues identified in the Gorga collection through a multi analytical approach. A part of the samples was already analysed and previously reported [29]. Nevertheless, the present work increased the number of analysed samples for each red hue and four orange samples were included.…”

“…Furthermore, a new set of 38 opaque red sectilia was selected and analysed by colourimetric measurements, optical microscope and reflectance spectroscopy, to confirm and establish the red hues identified by naked eye observations. In the previous publication [29], the colouring agent in each red hue was not identified with certainty. In this investigation, the crystalline phases that affect each hue, were identified through new measurements by means of FEG-SEM, Raman spectroscopy and X-Ray diffraction, allowing to clarify the nature of the colouring agent.…”

“…The selected samples were studied by colourimetric measurements (except samples AR2, R2, R5, R6, R11 and R14, due to their small size) and fibre optical reflectance spectroscopy (FORS) [29]. MAYA 200 PRO from Ocean Optics spectrophotometer with a single beam dispersive optical fibre was used together with a 2048 CCD Si detector that allows operating in the 200-1050 nm range.…”

“…Optical microscopy observations were conducted with a Zeiss Axioplan 2 Imaging system (HAL 100) coupled to a Nikon DXM1200F digital camera (Nikon, Tokyo, Japan) and ACT-1 software (Act 1 Systems, Los Angeles, CA, USA), with different illumination modes (bright field and dark field) [29].…”