Thursday, January 30, 2013
One of the goals of this season is to create a treatment proposal for the paintings that remain on the walls in the King’s Bedroom. One wall of this room has the most intact section of painting in the Palace. The site has been excavated several times in the past, and many fragments of the paintings that once decorated the floors, walls, and ceilings were removed to museums and storerooms. Some are on display in the Egyptian Museum in Cairo, and others are in the Metropolitan Museum in New York (for one example, see blog post: http://imalqata.wordpress.com/2010/02/11/112/)
In the decoration that remains, ankh and sa signs are separated by a niche palace façade motif, under which is a wave pattern. To create the paintings, the mud-bricks were first plastered with fine mud mixed with straw. This plaster was then painted with Egyptian green and blue, yellow and red ochre, carbon black, and white – possibly huntite (the white paint on the ceiling fragments from this room was analyzed and identified as huntite by Waseda University, one of the expeditions that worked in the Palace in the 1970s). All of these colors are inorganic and will not fade, but they are only loosely bound with the mud and so the pigments are likely to wear/rub away.
Archaeological objects, whether small like beads or large such as the remains of the palace, become in equilibrium with the ground in which they are buried. When an object is excavated, it is removed from this insulating equilibrium, which shocks the object. Wind, moisture, pollution, animals, and humans now have access to the object, hastening decay. For many years, the decorated wall of the Kings bedroom was unprotected from the elements. In the 1990s, there was a heavy rain in Luxor and the upper parts of the mud brick wall and the painting began to deteriorate, running in rivulets down the suurface. These rivulets and the tide lines caused by the ensuing flood still remain on the walls. These areas of mud are hard and stick to the paint underneath.
In addition to the streaks of hard mud, the paint on the wall is “alligatoring.” This is a process whereby the paint cracks in a scale pattern and begins to peal around the edges of the scales. This is likely due to the rain mentioned above; the wall painting would have dried faster than the thicker mud-brick walls, causing stress to the paint matrix. There are also voids in the mud plaster behind the paint as well as large areas of loss.
At some point, in an attempt to protect the painting, cardboard was placed against the painting surface and a protective mud brick wall was built in front of it. This season we removed the protective wall of mud-brick in order to assess the condition of the paintings. So far I have tested methods of removing the rivulets of mud, removing the dirt overall, and removing the cardboard. The rivulets can be removed by dampening the mud with water on a brush and mechanically removing the mud with a scalpel. A small area was tested successfully. A similar method was used with the cardboard. A damp sponge was held over the area to moisten and soften the cardboard and mud was removed mechanically with a scalpel. This process was repeated until all of the cardboard and mud were removed.
So far there has been no successful method to remove the dirt covering the painting overall. Use of water, enough to remove the dirt with swabs of cotton or a sponge causes the underlying mud plaster and paint to run. Blotting with damp acid-free tissue and mechanical methods, such as dry sponges and erasers, are not effective. Ethanol (which I’m testing above), an alcohol, causes the paint to run as well, even when the swab is barely damp and only lightly touches the surface. Acetone is the most effective; however it does not remove all of the dirt and the mechanical action of rolling the swab displaces some of the paint. As the decoration which is left is still readable behind the dirt, the dirt will be left until a method of cleaning is found where the minimal loss of pigment is outweighed by the effectiveness of the cleaning.
A sacrificial layer of mud has been placed along the edges of the mud plaster in the most damaged section. This layer will hopefully prevent further detachment and loss of the mud plaster and thus the wall painting. Only a small section has been coated as I wish to see the behavior of this layer and the mud plaster/wall painting after a period of time. Although this action should cause no damage, it is better not to treat the entire wall until we know that this is an effective treatment. Three fragments will be consolidated with three consolidant options as well; an acrylic dispersion (like Elmer’s glue only more reliable), a cellulosic (Klucel G – hydropropylcellulose), and ethyl silicate. The ancient wall paintings will be covered with a false wall of mud-bricks with clean sand as insulation to protect them from further deterioration at the end of the season. The consolidated fragments will be buried with the wall and the effectiveness of the consolidant and the use of a mud sacrificial layer will be analyzed upon my return (hopefully next year!) to Malqata.