A new lightweight support for the restoration and presentation of a large Roman mosaic

This paper presents a new technique employed in the construction of a lightweight backing for the Roman floor mosaic XIII.8 from Emona (Ljubljana, Slovenia). The rather large mosaic did not remain in situ but was instead lifted in 1997 before being restored and reassembled during a long and demanding conservation process between 2013 and 2014. Due to the size of the mosaic and subsequent demands associated with its presentation, as well as the need for easy handling when carrying and assembling the restored fragments, a necessity arose to develop a lightweight, compatible and easily removable support. Hence with an investigation of mechanical properties of lightweight mortars based on natural hydraulic lime was carried out. A low mortar density was obtained via the use of a lightweight aggregate composed of recycled glass beads. Conservation–restoration processes included documentation, cleaning, application of the new support, retouching and reassembly of the mosaic fragments.