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 world wide. Within this context, nano Ca(OH)2, the so-called nanolime, has been investigated as a promisinginorganic 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 maximizethe protective effects of nano Ca(OH)2 have been made by researchers. In this review, the developmentof synthesis methods for nano Ca(OH)2 is firstly summarized. Nanolime stability and carbonation, whichsubstantially 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 andstone artwork and deacidifying paper relics. In the Synthesis, Properties, and Applications sections, thechallenges 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 andits application in heritage conservation.