For our first meeting of 2018, OCG was delighted to welcome Bianca Madden, an independent art conservator who specialises in wall paintings, sculpture and polychrome or gilded surfaces, to talk about her work on the fifteenth century BCE Theban tombs in Egypt. Bianca took us on a spectacular virtual tour of the tomb chapel of Sennefer, which is very typical of many Theban tombs in regard to its condition and state of preservation. Her presentation showed the group not only the method of construction and the nature of the painting media but also the conservation approach that she and an international team of conservators took to reveal details that had been obscured for centuries, largely due to damage caused by natural degradation over time as well as previous human activity.
The conservation project at Sennefer began in 2001 as a joint enterprise between Brussels and Liège Universities as a part of their research and study project at Sennefer which started in 1999. Unlike the burial chamber of Sennefer, which has long been open to the public, the tomb chapel is unlikely to be opened for public viewing due to its extensive damage and fragmentary state. The approach to the conservation of the tomb was as a monument which would primarily be used for study and research rather than tourism. This intended research function guided the conservation approach, with a clear emphasis on minimal intervention and maintenance of the integrity of the tombs rather than restoration.
Damage to the tomb came from several sources, some historical and some more recent. The tomb, in common with many of the Theban tombs, had a history of human occupation, and until 2008 one hall was still being used for storage. This human activity had lead to heavy soot, mud and mould deposits on the interior walls and ceilings in particular. Attempts by early Egyptologists to reveal the wall paintings beneath the dirt layer by water washing had caused mobilisation of the water soluble tempera-based media, with irreversible losses to both the figures and the backgrounds. Insect pests had also been an issue related to the human occupation and the stabling of animals within the tomb, and masonry bee nests were burrowed into the walls. However, where losses had occurred to the plaster, the damage had revealed fascinating aspects of the construction of the tombs and the preparation of the walls for painting. The stratigraphy of the plaster layers was revealed over the hewn limestone rock, and in some areas the clear evidence of the hands that had applied the initial rough plaster layer several millennia previously was still visible.
The conservation was undertaken in two phases: to stabilise the construction of the tomb rooms and to clean and stabilise the wall paintings themselves. The nature of the rock strata on the site had made the detachment of the plaster more liable, so stabilising the ceilings in particular was a primary concern. A low humidity, lime-based mortar, PLM-A, was used to readhere loose areas of plasterwork. The introduction of this new material was restricted only to where it was strictly necessary with edge repairs being used rather than infills wherever possible to maintain the constructional evidence.
Phase two was the cleaning and stabilisation of the media. Bianca began by showing how the paintings were built up in layers, with some incredibly vital images of underpainting and the use of a grid system for figures to ensure evenness and regularity of the form.
It was a revelation to see that not all the paintings were two dimensional but had texture and relief through applied plasterwork features to areas such as head dresses, the effect of which was enhanced further with localised applications of varnish.
Such features contributed to making the cleaning and stabilising of the media a painstaking process. There were three approaches to removing the damaging and acidic soot and the heavy mud deposits. Brushes combined with blown air were used to remove loose deposits, followed by surface cleaning using a wishab sponge, a type of latex cleaning product that absorbs dirt but crumbles as it is moved over a surface, limiting the abrasive capacity and reducing the risk of residues. Heavy mud deposits were scraped away under magnification using a scalpel, revealing in many cases very well preserved paintings below. Spot tests showed that a very minimal and localised application of moisture would remove the remaining dirt deposits. A poultice of PLM-A, applied through Japanese tissue, was used with startlingly effective results to wick away residual dirt, as the images below show. The alkalinity of the lime mortar also had the effect of deacidifying the soot deposits, resulting in a neutral surface pH. Where necessary, pigments were consolidated with carboxymethyl cellulose solution.
Ceiling before cleaning, and after
The many and varied questions at the end of the presentation showed the level of engagement and interest of the group, and we are grateful to Bianca for sharing her fascinating work with us. It felt as though we were getting a very privileged glimpse into a highly significant site and to have Bianca’s expert guidance and knowledge to interpret and explain the magnificent images was both hugely enjoyable and invaluable to increasing our understanding of this specialised conservation project.
Our sincere thanks go to Bianca for presenting to the group, and to the Oxford Conservation Consortium and the Chantry Library for kindly hosting the event.
Tomb images kindly provided by Bianca Madden and Hugues Tavier on behalf of the University of Liège and the Archaeological Mission to the Theban Necropolis – Université libre de Bruxelles, and the image of the group kindly provided by Nikki Tomkins on behalf of the Oxford Conservation Consortium.