Nano-Lime for Consolidation of Plaster and Stone

Abstract

AbstractStone consolidants should, ideally, be physically and chemically compatible with the materials requiring consolidation. The theoretical principle of getting calcium hydroxide into a decayed calcareous substrate, and allowing it to carbonate, has long been understood and was the reason why limewatering (a method refined by Professor Robert Baker in the 1970s and 1980s) was used on several important projects, including the carvings to the west front of Wells Cathedral. Nano-lime has been developed as a method of consolidating limestone and lime plasters because it offers theoretical advantages over traditional materials such as limewater and lime grouts. Preliminary investigations to determine its performance characteristics prior to its specification and subsequent use on medieval wall paintings were undertaken by Hirst Conservation in 2010. Although these tests were limited to only a few materials, results were encouraging and highlighted some of the product's advantages and disadvantages. The results clearly show that rates of penetration vary significantly according to the type of material, its porosity and other factors. Nano-lime dispersed in alcohol can work well as a consolidant if used in the correct manner, allowing time for maximum penetration, precipitation and carbonation of the nano-lime. This may take days or even weeks for each saturation. Additional informationNotes on contributorsPaul D'ArmadaBiographyPaul D'Armada, BSc (Hons), PGCEPaul D'Armada joined Hirst Conservation in 1986, having studied and taught earth sciences and physics. As Principal Conservation Scientist, he has significant in-depth understanding of materials science as well as conservation. A specialist in historic plaster and paint analysis, Paul is also a specialist paint technician, advising on the specification of appropriate paint systems (both traditional and modern), together with their production. His most recent research paper focuses on the innovative technique and use of nano-lime technology.Elizabeth HirstElizabeth Hirst, ACR, IHBC, FRSAElizabeth Hirst is the principal conservator of Hirst Conservation (established 1986). She trained as a stone and medieval wall painting conservator under the auspices of Professor Robert Baker and Mrs Eve Baker. As an architectural conservator, she advises on material consultancy, fine art and historic buildings conservation. She joined the editorial board of the Journal of Architectural Conservation in 1995, becoming a consultant editor in 2005. She was also co-editor of Windows: History, Repair and Conservation.