The conservation of the 2 nd century AD Roman barge Lyon-Saint-Georges 4 (LSG4) in 2014 provided the opportunity to remove 26 linear meters of the caulking, consisting of a mixture of tar and textiles from between its sides and the flat-bottom. Attempts were made to unfold the material based on prior experience, but this resulted in the destruction of the samples. A new and readily accessible solution had to be found, which would better conserve the material. This new process consists of heating the samples in demineralized water to 100 °C, thus the tar becomes plastic enough to unfold the textiles. Two questions arose during this project: first, how to record each step of the process, because material changes are irreversible, and secondly, how to conserve the textile, avoiding as much degradation as possible during the unfolding process.

The study of the textiles suggests that the material is caulking (used after the wooden ship was assembled) as opposed to luting (utilized during the construction of the wood). This helped provide new data for archaeological assessment. Additionally, the analysis of the images of the partially unfolded textiles will help us to understand the way Roman caulkers prepared and used the textiles. Due to the good preservation conditions (an anaerobic environment, impregnation with tar and the constriction between the planks in the wreck itself) this component of the LSG4 conservation project allowed us to recover the most important group of Roman textiles in Europe consisting of nearly 3 m 2 . This has led to new research questions: were these textiles specifically chosen for that use? Were they recycled from nearby? Do they present specific technical properties?