By Alice Rugheimer, Senior Paper Conservator, Department of Conservation at the British Museum
The Atlas arrived in the Department of Ancient Egypt and Sudan as a bound album of 56 pages of black and white prints, and colour-printed and hand-coloured maps and cross-sections, plus one page of coloured drawings of insects. The condition of the pages varied according to the type of paper used. There were three main types of paper, the most problematic having extensive foxing and mould damage (Fig. 1, above)...
...and being generally discoloured to a dark beige/brown colour making it difficult to distinguish the lines of the images (Fig. 2).
The environment they had been kept in prior to acquisition by the Department of Ancient Egypt and Sudan, and any previous treatment or repairs carried out also had a bearing on their condition. Three of the pages had very large tears which had been repaired using pressure-sensitive tapes. (Fig. 3). This type of tape is damaging to the paper and leaves an adhesive residue which darkens with time and is disfiguring and difficult to remove.
The conservation procedure began by removing the pages from the album. They were then grouped according to treatment required and type of media. Each page was photographed before treatment. A minimal trimming was required to remove adhesive and paper debris from the bound edges. Any remaining debris was removed using an aqueous gel poultice then lifting with a scalpel, followed by cleaning with grated conservation quality eraser to remove any surface dirt. In order to remove the discolouration from the papers it was necessary to wash (Fig. 4) and, where possible, to bleach the pages.
Certain types and conditions of paper and/or media may not be suitable for washing by immersion in water, for example very acidic, foxed, fragile paper and powdery, flaking and water-sensitive media. A number of pages of the Atlas came into these categories and they required a different method of washing which entailed humidification then placing individually on a sheet of non-woven viscose fabric containing tiny capillaries which act as a siphon. This allows clean water to flow through the fabric, drawing impurities out from the object and into a tray below in a cascade system (Fig. 5). The process took four hours for each print. Much brown discolouration was washed out of the pages.
Light bleaching was chosen as a gentle method which gives an even tone to the paper. Prior to aqueous treatment the paper was tested for the presence of lignin, which causes it to darken when exposed to light, in which case it would not be possible to use the light bleaching technique. The results were negative. Only pages which could be washed by immersion in water were suitable for light bleaching. After washing they were submerged individually into an aqueous alkaline solution. A bank of UV-filtered fluorescent lights was positioned above them and they were bleached for six hours, under constant supervision (Fig. 6).
Depending on the paper and the media, many of the pages could be humidified then washed by immersion in a bath of water and then rinsed in an aqueous alkaline solution in order to leave a buffer in the paper against possible future acidity.
Any pressure-sensitive tapes were lifted using tweezers while the pages were submerged in warm water. The dark adhesive stains were later treated with an organic solvent. Residues from pressure-sensitive tapes are very difficult to remove and despite lengthy treatment stains often remain (Fig. 3).
Further brown discolouration was removed from the paper during light bleaching. After this treatment the pages were washed in clear water and then rinsed in an aqueous alkaline solution to leave a buffer in the paper (Fig. 7).
Light bleaching procedures were carried out in accordance with recommendations resulting from research and experiments by members of the Department of Conservation and Scientific Research of the British Museum.**
After the washing, bleaching and alkaline treatments the pages were air dried on racks then brushed with a sizing solution to strengthen them and make them less absorbent. They were air dried again (Fig. 8) and pressed.
Humidifying chamber shown here on top of air drying racks.
Any necessary repairs were carried out using Japanese paper and gluten-free wheat starch paste. The treated pages were photographed for inclusion in the in-house database system with the ultimate aim of making them accessible online. Since completion of the conservation process the prints have been stored in individual clear polyester archival sleeves in plan chests in the Library of the Department of Ancient Egypt and Sudan where they can be consulted by readers (Fig. 9).
The treatments proved successful in removing damaging acidity and impurities from the paper and rendering the images considerably clearer so that they could be digitised and viewed online by a larger audience. This in turn means that the pages will not need to be handled often and they will be preserved in conservation quality storage for the future.
Reisen in Europa, Asien und Afrika, mit besonderer Rücksicht auf die naturwissenschaftlichen Verhältnisse der betreffenden Länder unternommen in den Jahren 1835 bis 1841.
Joseph von Russegger
This article was written by Alice Rugheimer with support from Susanne Woodhouse.
* Conservation treatments laid out in this article should only be carried out by a professionally qualified paper conservator.
** Light bleaching procedures were carried out in accordance with recommendations resulting from research and experiments by members of the Department of Conservation and Scientific Research of the British Museum:
M. Hacke, V. Daniels, J. Rayner, A. Rugheimer, L. Gibson: The Effect of pH on the Aqueous Light Bleaching of Paper, Science Report Envelope No 2010/7391, Department of Conservation and Scientific Research, British Museum.