Description du sujet de thèse

This thesis focuses on the study of glass from the Roman period.
Glass in antiquity was produced in primary workshops located east of the Mediterranean and processed in secondary workshops scattered throughout the rest of the Empire. Bleached antique glass can be divided into four groups: naturally bleached glass, glass bleached by adding antimony, by adding manganese, or by a mixture of antimony and manganese [1]. The latter are considered to come from recycled glass. However, observations made on the numerous bodies discovered during preventive excavations tend to blur this strict separation, and raise the question of the reworking of the material by the glassmakers themselves.
Since 2021, we at LSI have been developing a new method for identifying the category to which colorless Roman glass belongs. This is based on time-resolved photoluminescence (PL) detection of Sb3+ (420 nm) and Mn2+ (520 nm) ions under pulsed UV laser excitation.



The aims of this thesis project are to use time-resolved photoluminescence to help understand the production and recycling of colorless glass in antiquity, focusing in particular on the site of Reims (material studied by Aurore Louis). During the ancient period, Reims was the capital of the province of Gaule Belgique. This area, excavated since the 1990s, has yielded a large number of glass objects and has recently revealed two major glassmakers' workshops dating from the 3rd century AD, comprising three manufacturing furnaces and two material production/recycling furnaces. It turns out that the glass from the city's consumption sites (houses, warehouses, tombs) is mainly colorless glass. The question of local manufacture in the said workshops was therefore raised.

The project will be divided into 3 parts

1) Optimization work on the sorting method based on time-resolved PL.
In particular, we still need to understand the origin of the component at 380 nm. To this end, we will develop new model glasses and carry out PL and excitation measurements at 300 and 10 K. We will also work on the infrared emission of the glasses. We also have to finalize the digital and automatic processing of the spectra and the program developed in Python language.

2) Study of the glass corpus from Reims and other surrounding funerary sites (Velaines, Argonne....) to answer the following questions:
- is antimony-bleached glass produced in primary workshops or bleached on site?
- Is the glass recycled from finished products, or is it produced locally in secondary workshops?
- Are objects produced in the Reims workshops sold locally or exported?
To do this, we need to demonstrate the correlation between glass residues and finished products, based on their composition and, in particular, their content of bleaching agents (Mn and Sb). The thesis work will have to be carried out in collaboration with the archaeologist, so that the results of the analyses progress in parallel with the archaeological findings.


3) Work on glass recycling
Glass recycling was an established part of the Roman economy [2]. Baskets filled with fragments of colored or colorless glass have been unearthed in the cargo of the Embiez wreck in the Mediterranean and the Julia Felix in the Adriatic [3]. Glass is certainly recycled for a second life, but it is difficult to assert that all the glass in circulation at the time was recycled, especially as multiple remelting operations lead to a loss of final glass quality. In particular, we want to understand the impact of remelting cycles on iron and manganese redox, on glass structure (Raman spectroscopy) and on glass coloring. On this subject, we will set up an experimentation plan with glassmakers specialized in old techniques. We will be remelting glass at LSI, using both synthetic and archaeological glass. The remelts will be carried out in both a gas-fired and a wood-fired furnace, to compare the impact of the two furnaces.



[1] Gliozzo E. et al. Archaeol Anthropol Sci 9 (2017) 455–483
[2] Chinni, T.; Silvestri, A.; Fiorentino, S.; Vandini, M. Once upon a Glass–Cycles, Recycles and Reuses
of a Never-Ending Material. Heritage 2023, 6, 662–671.
[3] Silvestri, A.; Molin, G.; Salviulo, G. The Colourless Glass of Iulia Felix. J. Archaeol. Sci. 2008, 35, 331–341

Contexte de travail

The PhD student will do his thesis at the Laboratoire des Solides Irradiés UMR 7642 based at the Ecole polytechnique. The doctoral school is that of IP Paris. This work will be carried out mainly at LSI, in close collaboration with the archaeologist Aurore Louis, based in Reims (INRAP). Other collaborations will take place with glass makers and other laboratories.

Contraintes et risques

Travel will be required to take part in conferences and collaborations, mainly in France.