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Title: The kinetics of salt weathering of porous materials : stone monuments and wall paintings
Author: Sawdy, Alison Mary.
ISNI:       0000 0001 3554 3994
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2002
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The aim of this research is to improve ways of reducing the damage caused by salts to cultural property. A specific focus of attention is the use of environmental control as a passive measure. Environmental control attempts to specify optimum ranges of relative humidity (RH) and temperature (T), to control salt phase transitions. To undertake environmental control a range of suitable climatic conditions are selected on the basis of thermodynamic calculations. These calculations are used to determine a range of RH and T in which salt phase transitions are minimised, and require very accurate analytical data of the salt content of the object. Unfortunately, in practice it is rarely possible to maintain this close range of RH and T. It therefore becomes necessary to know the speed of salt deterioration at levels of RH and T outside the optimum range, and establish the time it takes for damage to occur. Consequently, for environmental stabilisation measures to be successful, there are two critical areas where further research is mandatory. Environmental control is dependent on reliable information of the object's salt content, and better methods for determining this are needed. Moreover, an understanding of the rate of salt phase transitions is essential, so that the degree of control achieved is sufficient to limit the damage. These two issues are addressed by the present research. The work comprised both ex situ and in situ investigations. A key feature throughout was the use of statistical methods for the design of each component of the project. This approach provided a means of unravelling complex multi factor interactions, and gave clear unequivocal results. Laboratory experiments were undertaken to assess the rate of water vapour sorption by salt-contaminated stone and limeplaster. Experimental design and analysis of variance techniques were used to determine the relative significance of the following kinetic factors: RH, T, airspeed, salt mixture composition, salt concentration, and support type. In situ investigations were carried out at Cleeve Abbey, Somerset, to study the Cl3th wall paintings in the Sacristy over one year. The work included documentation, sampling and analysis of the paintings, and environmental monitoring. The results were subjected to statistical analysis to assess changes in the salt distribution, spatially and over time, in relation to the environmental conditions. The outcome of the ex situ and in situ investigations collectively provide important new information about the kinetics and mechanisms of salt damage, and reveal better practical methods for assessing and ameliorating these problems
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Cultural property