Nano Ca(OH)2: A review on synthesis, properties and applications

The restoration of weathered cultural relics with suitable materials has been a highly challenging worldwide. Within this context, nano Ca(OH)2, the so-called nanolime, has been investigated as a promising inorganic nanomaterial in the field of heritage science for two decades, mostly due to its excellent compatibility and ageing resistance compared with other organic materials. Substantial efforts to maximize the protective effects of nano Ca(OH)2 have been made by researchers. In this review, the development of synthesis methods for nano Ca(OH)2 is firstly summarized. Nanolime stability and carbonation, which substantially affect its consolidation and protection performance in heritage conservation, is also discussed. Successively, we focus on the application of nano Ca(OH)2 in consolidating wall painting and stone artwork and deacidifying paper relics. In the Synthesis, Properties, and Applications sections, the challenges that affect the performance of nano Ca(OH)2 are identified, and potential methods for addressing them are proposed. This review is expected to promote further research on nano Ca(OH)2 and its application in heritage conservation.