This week, Conservator Lynn Teggart from the National Library of Scotland describes conservation treatment of two large maps from the Bartholomew collection. This article was originally posted on the NLS blog.
The Newbigging Farm map
The first map shows Newbigging Farm and dates from 1864. Examination of satellite maps suggests that the farm still exists, and is based south west of Edinburgh close to Penicuik. The map is printed in black ink on a heavy weight, woven paper, with colour added by hand using water colour paints, and a layer of varnish applied on top. The paper has been lined onto a linen support, and wooden rollers are nailed to the upper and lower edges of the map.
The map was prioritized for treatment because it was in very poor condition. There were several large tears running horizontally across it, causing the severe distortion of the surface. The paper and linen layers were detaching from one another, particularly along the edges. The map was extremely dirty and the varnish layer had yellowed, obscuring the detail of the map.
Several options for treating the map were considered, ranging from the minimal intervention option of surface cleaning and re-housing, to more invasive treatments. It was eventually decided that a full treatment was required, involving removal of the linen support, removal of the varnish layer, washing and de-acidification of the paper map and re-lining with Japanese tissue. This was considered necessary in order to avoid further damage occurring in the future and allow the map to be handled safely.
The treatment was quite time-consuming and involved several testing phases, for example to find a way of removing the varnish successfully and to identify a suitable lining paper. However, the end result was well worth the effort: the appearance of the map was improved dramatically, and it was stable and robust.
The City of Edinburgh map
The second map to be treated shows the City of Edinburgh and its Environs, and is dated 1817. It is constructed in a similar manner to the Newbigging Farm map, with black ink printed onto a heavy weight, woven, cream coloured paper, a layer of varnish on the front and a linen backing.
The aims of the treatment were to stabilise the map and allow it to be safely consulted. It also needed a housing system to protect it from damage while it was in storage. It was part of a large group of maps all of which required attention, and so the treatment method chosen had to be quick enough to allow the other maps to be worked on afterwards.
The condition of the map was again fairly poor: it had an area of loss down the centre corresponding to where it had been folded previously, and the paper and varnish layers were fragmentary and flaking in places. The linen backing was weak and very dirty, and the varnish had discoloured to an unpleasant orange-brown.
On this occasion a fairly minimalist treatment was chosen. The varnish layer and linen backing were retained, and the map was dry cleaned with a chemical sponge rather than washed with water. The reverse of the map was strengthened using strips of aerolinen, which is an extremely strong textile developed for the aviation industry. Loose fragments of the upper surface of the map were readhered to the backing and losses in the paper layer were infilled. The map was too large to store flat, so it was rolled around an extra wide roller and placed inside a cube tube box.
Following treatment the map was relatively stable and much less vulnerable to accidental damage than previously. However, the surface was still at risk of flaking because the varnish was still in place, and the appearance of the map had not been transformed to the same extent as for the Newbigging Farm map.
These case studies show some of the treatment options available for large maps, and demonstrate the challenging decisions that have to be made in order to care for the Library’s collections in their entirety. The principles at the heart of every conservation intervention are reversibility and retreatability, which ensure that we can always return to an object in the future if circumstances change.