Institute of Archaeology
University College London
Consolidation of wall plaster with calcium caseinate
Helen V. Farmakalidis
The mapping and recording of ancient stonemasonry
Eleni A. Loizides
Ancient faience: Its manufacture, deterioration, and conservation
Tracy C. Richardson
The treatment of waterlogged wood is an expensive process and many large scale structures cannot be treated because of the cost. There is a need for effective methods which can offer alternative options when considering whether to conserve large structures which are of timber in a reasonably sound condition.
This study looks at the seasoning methods used by the timber industry to dry freshly cut wood and makes an attempt to dry waterlogged wood by a similar procedure. A humidity chamber was used to test dry samples of waterlogged wood by elevating the temperature to 40°C and controlling the relative humidity to specific levels over pre-determined periods. The intention was to use reasonably sound wood which was wet rather than waterlogged but in the event a mixture of conditions was used. The method was assessed in comparison with uncontrolled air-drying, controlled air-drying, and freeze-drying and the results were judged on how much checking or splitting occurred together with loss of surface detail. The anti shrink effectiveness was also used as a means of assessment. All drying methods were carried out with the wood as received and after pre-treatment with an impregnant. It was found that the method as used for these experiments was not effective for wood above 200% Umax, but showed some promise for wood of 200% Umax or less, especially when an impregnant was used. Future research was recommended using different time scales and relative humidity settings in the humidity chamber and a greater variety of categories for assessment of the results.
Calcium caseinate is a traditional material which conservators used for the consolidation of wall paintings. This dissertation is investigating the use of calcium caseinate on the conservation of wall plaster. Casein is an organic compound belonging to the proteins class and exists in milk as calcium caseinate. The consolidant is prepared by dissolving casein in an aqueous alkaline solvent. The bonding power, behaviour, rate of hydrolysis, working time, water resistance, and other properties of the consolidant depend on the different alkaline solvents.
The aims of the experimental work are the investigation of the calcium caseinate performance by examining the penetration properties, consolidating ability, and durability of different types of calcium caseinate on different types of lime plaster. This can be achieved by the examination of the capillary action and evaporation rate of water on samples which have been treated with calcium caseinate (casein + lime water). After application of the consolidant, the samples were tested for weathering resistance and observed salts crystallisation and biodeterioration on the samples.
The water absorption and evaporation tests prove that all the types of calcium caseinate increase the strength of the lime plaster samples and support the structure together; but not all preserve these consolidating abilities after testing. The moisture presence not only produces biodeterioration of the casein but also discoloration and it breaks down the structure of the consolidant by destroying the coating which holds the structure of the plaster, so moisture reduces the consolidating abilities of the calcium caseinate. Hammarsten casein had better preserved the consolidating ability after testing, the plaster was not water resistant but the calcium caseinate supported the plaster's structure together.
This dissertation looks into the different techniques used for the recording of the deterioration found on stonemasonry. Reference is given to many techniques, however, the project focuses on a specific technique that has been developed in the last 10 years and has been used in the past to record monuments such as in Petra and Greece. By this technique the condition of the stone is recorded through visual examination. The technique makes use of a classification scheme of all the weathering forms present on stonemasonry. The stone is studied in detail and a map/drawing is produced with all the different weathering forms recorded on it.
In order to assess the above technique, a monument in Nicosia, Cyprus, known as the Famagusta Gate has been used as a case study. The condition of the building has been recorded by using the above technique. Through this case study, certain conclusions were drawn concerning different aspects of this technique such as its efficiency, ease of application, and usefulness.
Lithological investigations were also carried out on samples taken from the monument and from nearby quarries, and the stone was identified as a calcarenite sandstone. Porosity and acid immersion tests were also carried out on the stone.
Although the technique did produce the results expected and did provide a lot of information concerning the state of the building and the way the stone is weathering, it was concluded that this technique may perhaps be too detailed and confusing for the requirements of a conservator. It was felt that a simpler recording method could be used, one that would require less time and would be easier to interpret. Also, it was felt that the technique is not reproducible, since it relies on the record's objectivity.
Environmental monitoring of the Great Painted Staircase at Knole was undertaken for the National Trust. The project was mainly concerned with determining whether moisture has been responsible for deterioration of the staircase's wall paintings, either in the form of condensation, variations in relative humidity (RH), visitor moisture, or damp. Other factors such as previous restoration treatments, visitor damage, light, and salts were also considered. A condition survey of the wall paintings enabled correlations to be made.
Problems encountered in monitoring and some approaches that have been used, were noted from the conservation literature. This information was useful during the planning of the survey and in the interpretation of the results. Consequently an approach developed by the Courtauld Institute of Art was used. Temperature and RH data is manipulated to show whether the dew point temperature, which is when condensation forms, has been reached, and the absolute humidity of the exterior environment is compared with that of the interior to see if there is any ingress of moisture. Data was also examined for correlations with the weather, such as sunshine and rainfall and levels of damp were determined with portable meters.
Large decreases in RH were caused by sunshine falling directly onto the wall paintings, and occasionally RH was sharply lowered in the entire room on very sunny days. RH variation was mainly in response to temperature changes. No evidence was found of major problems with either condensation or damp.
The results were used to recommend a preventive conservation strategy based upon "conservation heating" and window blinds. These measures will reduce variations in RH and can only be beneficial to the wall paintings.
This dissertation examines ancient faience, a material that is not greatly understood. It focuses on the relationship between manufacture and deterioration, and it investigates how faience has been treated in the field of conservation. An overview of what faience is and how it is made is given, as well as a discussion of how it deteriorates. The three glazing methods of efflorescence, cementation, and direct application are described, and the research on faience published in the last 75 years is presented. The relationship between the manufacture and deterioration of faience is examined through replication studies. Although it is shown that the three glazing methods do not cause specific forms of deterioration, the manufacture of faience does cause certain stresses to objects. Lastly, to learn how faience has been understood in the field of conservation, the results of a questionnaire sent to conservators in the United Kingdom and the United States are discussed and compared to the observations made in the published research. In general, numerous types of deterioration have been found with ancient faience, but it poses few conservation problems.
The use of burial and reburial in archaeology for site preservation is becoming more and more prevalent with the growing awareness of its potential benefits. Yet the effects and techniques used in the field have only been sporadically documented, leaving the practice without recognised guidelines or cause and effect criteria for its implementation. This dissertation will look at some of the scientific principles relevant to burial. This background information will then be coupled with existing knowledge regarding the mechanisms of decay in burial environments. Different elements pertaining to the design of burials will then be outlined in regard to their effects on the preservation of buried archaeological material. Finally, goal oriented design will be discussed using published examples of different burial and reburial projects.
This dissertation assesses what is done at present to educate the public, especially children, in the area of conservation of archaeological and historic artifacts.
Most people understand what an archaeological site is. Many of England's older cities have had an excavation over the last ten or twenty years, which will have caught people's attention. However few people have an idea what happens to objects after they are excavated, beyond being dusted off and placed behind glass. There is also a belief that once an object has made it to a museum it will be safe. While this is generally true, lack of resources, including financing can mean an object does not always receive the care and attention needed to preserve it.
Many institutions increasingly need to be seen as financially self sufficient. Nevertheless, museums often need to carry out lengthy and costly conservation work behind the scenes. With the current lack of understanding by the outside world of the importance of this work, it will remain a constant struggle to attract funds to this area. Once an issue is brought successfully to public attention and gains an understanding audience, it is more likely to attract greater funds and resources. So there are good reasons to promote the work of the conservator and make it a regular part of exhibitions and education programmes.
This dissertation initially focuses on the work of eight museums. It also seeks to establish what work is being carried out across the country in this area and what are the views and aspirations of those in the museum world. The findings are based on a questionnaire sent to 130 museums across the country. The responses are analysed and key observations are highlighted. The last chapter then suggests new ways to help children understand some important aspects of conservation. The particular area focused on is why and when some materials deteriorate while others do not. Finally it considers general education programmes and suggests ways that conservation could become more involved in these.