Cit:Thickett.etal:2017

From Saltwiki
Author Thickett, David; Stanley, Bethan
Year 2017
Title Management of sodium sulfate damage to polychrome stone and buildings
Bibtex @inproceedings {Thickett.etal:2017,

title = {Management of sodium sulfate damage to polychrome stone and buildings}, booktitle = {Proceedings of SWBSS 2017. Fourth International Conference on Salt Weathering of Buildings and Stone Sculptures, University of Applied Sciences Potsdam, Germany, 20-22 September 2017}, year = {2017}, editor = {Laue, Steffen}, pages = {135-142}, month = {september}, organization = {Fachhochschule Potsdam}, publisher = {Verlag der Fachhochschule Potsdam}, note = {fulltext, conference paper}, key = {SWBSS2017}, doi = {10.5165/hawk-hhg/330}, author = {Thickett, David; Stanley, Bethan} }

DOI 10.5165/hawk-hhg/330
Link File:SWBSS 2017 Proceedings 135-142 Thickett Stanley.pdf
Notes in: Proceedings of SWBSS 2017 - Fourth International Conference on Salt Weathering of Buildings and Stone Sculptures. University of Applied Sciences, Potsdam, Germany, 20-22 September 2017



Bibliography

[Thickett.etal:2017]Thickett, David; Stanley, Bethan (2017): Management of sodium sulfate damage to polychrome stone and buildings. In: Laue, Steffen (eds.): Proceedings of SWBSS 2017. Fourth International Conference on Salt Weathering of Buildings and Stone Sculptures, University of Applied Sciences Potsdam, Germany, 20-22 September 2017,Verlag der Fachhochschule Potsdam 135-142, 10.5165/hawk-hhg/330Link to Google ScholarFulltext link

Abstract

English Heritage holds large collections of polychrome stone. Often the polychromy only remains as small fragments, loosely adhered to the stone surface with any original binders having converted to oxalate. The sixteenth century limestone Thetford Tomb fragments are amongst the most significant part of the collection. Salt analyses indicated very high concentrations of sodium sulfate present, (up to 1.5% by mass of the stone). Considering the very fragile nature of the remaining polychromy and the aggressive nature of this salt, strict preventive conservation is needed to ensure survival of the information. Theoretically, keeping the RH below the thenardite transition line (the RH is temperature dependant) should avoid any damaging salt transitions. Monitoring with acoustic emission in the storage environment, provided a direct tracing of salt transitions. When plotted against temperature, it became clear that transitions were occurring at between 3 and 7% lower RH than expected from theory. Tests with pure sodium sulfate powder coincided with the theoretical values. The most likely reason is the effect of the pore structure, particularly fine pores. The values are consistent for a single piece of stone and vary between pieces. A good correlation was observed between acoustic emission events and small pieces appearing on the imaging plate of a prototype particle deposition analyser. Loss of material from two interior building surfaces was monitored using a similar automated camera system. Inspection of the environmental data when material fell, shows similar depression of the RH below the theoretical values for sodium sulfate.