Conserving portraits of Kew botanists

I have recently completed conservation of a collection of 15 pastel and chalk drawings on paper, depicting portraits of notable botanists of the 19th century.

These are part of the Illustrations collections at Kew, originally from the Joseph Hooker collection and are by the Scottish artist Daniel Macnee (1806-1882).

Condition

The portraits were found housed in an open box and were stacked on top of each other, interleaved with tissue paper (figure 1). Without proper mounting they could not be viewed by researchers or go on display. Each portrait was severely discoloured, the paper was very brittle and the pastel was gradually being rubbed away.

Figure 1: The portraits before treatment, housed in a box and interleaved with tissue paper

Two of the portraits were still attached to a wooden frame and had severe tears across the entire centre of the paper support (figure 2).

      

Figure 2: Portrait of Asa Gray, before treatment
The paper is pulled around a wooden frame, leaving it vulnerable to damage such as the tears shown. The paper is also severely darkened probably due to prolonged light exposure. 
 

Five of the portraits had been previously ‘conserved’ and dry mounted with a heat set film. These had also been heavily re-touched with white chalk to disguise the discoloration of the paper (figure 3).

 

Figure 3: Portrait of Allan Cunningham, before treatment
The paper has been previously dry mounted with a heat set tissue and the background has been re-touched with white chalk, to disguise the darkening of the paper. These attempts at conservation were probably carried out in the 1970s.

Treatment

Pastel, chalk and charcoal are very difficult to handle and store, as they only sit on the surface of the paper and are very easily detached if moved or touched. The aim of the treatment was to re-house the pastel drawings to make them more accessible and prevent further deterioration.

The majority of the portraits were stuck to a poor quality board which was very acidic and had contributed to the deterioration of the paper. The board was removed from all of the portraits using a scalpel to pare it away from the back of the paper (figure 4).

 

Figure 4: Removal of the acidic backing board by gradually paring away with a scalpel.

Many of the papers were also torn along the edges and some had large tears across the whole image. These were repaired with small strips of Japanese paper and a paste made from wheat starch (figure 5).
 

Figure 5: Portrait of Thomas Drummond, verso, showing the repairs to the tears with strips of Japanese paper along the edges. The discoloration of the paper around the edges shows where a wooden frame would once have been in contact. Another drawing was also uncovered on the verso

The portraits were then hinged into deep window mounts to prevent anything coming into contact with the surface and stored in an archival Solander box.

 

Figure 6: Portrait of Thomas Drummond, before and after treatment

This was a very challenging project due to the very brittle supports and the fragile media. The portraits are now housed safely and securely in archival quality mounts and can be easily accessed and displayed.

Three of the portraits have been framed and are now on display in the Wolfson Rare Books Room window in the library Reading Room, along with some related items from the illustrations collection.

- Emma le Cornu -