Consolidating tomb mural plaster layer with nanolime

Mural paintings reflect valuable spiritual and cultural achievements of human civilizations and serve as crucial evidence for studying ancient customs, rituals, and clothing. However, deterioration of the mural plaster layer results in a decrease in the mural’s mechanical strength, thus posing a serious threat to its preservation. Nanolime (NL) is currently one of the most widely studied inorganic nanomaterials for the consolidation of cultural heritage in general, and mural paintings in particular, due to its excellent compatibility. However, there is limited research on the application of NL for consolidating the plaster layer of mural paintings. Here, we focus on ancient tomb mural paintings (ca. 1000 CE), investigating the consolidation performance of NL for its plaster layer. NL is homogeneously synthesized in the presence of additives and subjected to size-selection through centrifugation, yielding a narrowly distributed particle size of ∼40 nm—markedly smaller than the ∼180 nm obtained without centrifugation (NL-C). This novel NL is subsequently applied to the plaster layer of the tomb mural exhibiting limited impact on its pore structure and good penetration depth (1.2∼3.5 mm), which is significantly deeper than that observed in samples consolidated with NL-C (∼1 mm). More importantly, after consolidation with NL, the surface hardness of the plaster layer increases by ∼56 %, and the surface weight loss decreases by ∼67 %, demonstrating an effective consolidation performance. This study provides technical and methodological support for the application of NL in the preservation of ancient tomb murals.