The antique floor mosaic with the museum designation D1758 was discovered on Zoisova street in Ljubljana, allegedly lifted on 30 June and stored on 19 September, 1997 in the depot of the Museum and Galleries in Ljubljana. In 2018, it was brought to the working place of the Department of Restoration, and it’s restoration is the subject of this master’s thesis. The mosaic is made in the opus tesselatum technique with repeating geometric patterns consisting of white and black stones and reddish bricks. A large part of the nucleus and rudus lime mortar has been preserved, with the characteristic addition of crushed brick. The dimensions of the fragment before the intervention were 210 x 106 cm, after restoration and presentation on a new portable carrier, 220 x 112,5 cm.
In agreement with the mentor, co-mentor and museum conservator-restorer, the main starting point and goal of the work was the conservation-restoration of the mosaic to such an extent that it will be suitable for exhibition in the City Museum. At this time, we tried to conserve as much of the original plaster as possible, which meant that we revealed the condition of the face of the mosaic only after turning the fragment. First, the mosaic had to be roughly cleaned and gypsum plaster (added to the back for temporary reinforcement of the mosaic during transport after excavation) was removed. Then the back of the fragment was consolidated with conservation mortar and strengthened with a layer of lightweight mortar with glass aggregate. After removal of the protective gauze, the face of the mosaic was cleaned mechanically and chemically with ion exchange resins. The mosaic was then glued onto an expansion polyurethane foam and the gap between the support and decorative plaster (abt. 10 cm) was bridged with styrofoam. Finally, decorative plaster, grouting between tesserae and final retouching were performed.
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