Read about the conservation work which has been carried out on some beautiful watercolour tree portraits from Kew's Illustrations collection.
I am a paper conservator based in the Herbarium, Library, Art and Archives department, concentrating on items from the Illustrations collection. Among the varied artworks in the collection I recently treated a group of 23 Chinese tree portraits painted in watercolour on Chinese paper. This blog post describes some of the problems I encountered and the methods I used to conserve them.
About Robert Fortune
These watercolours were painted by an unknown artist who was engaged by the 19th century botanist, Robert Fortune, on his last journey to China in the 1850s. The majority depict a conifer with human figures painted at the base of each tree. An inscription inside the front cover of the portfolio explains further:
‘Chinese portraits of conifers all done by a native Chinese artist engaged by Robert Fortune.... The artist stipulated that he would only make the pictures if allowed to put a human figure in each...’
The watercolours came to me housed in a leather covered portfolio. Each watercolour was attached along the top edge to a thicker portfolio page and numbered.
Portfolio before treatment, 765 x 558mm
The condition of the watercolours presented a number of problems. Most evident was the very thin, weak Chinese paperon which they were painted, making them extremely vulnerable to further damage. They were much too fragile to be handled, viewed or exhibited. A few of the watercolours had severe tears caused by poor storage methods and rough handling. The paper had also yellowed very noticeably, most likely due to exposure to light or the degradation of additives in the paper. A small number of the watercolours had also been exposed to damp indicated by severe water staining in the form of dark tide-lines along the edges.
No. 2 ‘Keteleeria fortunei‘ (765 x 558mm) before treatment showing tears across the whole sheet and no. 22 ‘Juniperus chinensis’ (765 x 558mm) before treatment showing water damage along the left edge.
Aims of the treatment
The conservation treatments I was to carry out were primarily aimed at stabilising the condition of the paintings, and preventing their further damage and deterioration. This would entail removing them from their current housing, repairing structural damage, and re-housing them in accessible and safe mountings so that the items could be viewed and exhibited. As paintings which could potentially be exhibited as artworks, their appearance and the integrity of the images also needed to be considered.
Treatment started with the photography and documentation of each watercolour followed by testing of the pigments and inks after which they were removed from the portfolio pages. Tears were repaired from the back using Japanese paper strips and wheat starch paste as an adhesive. Japanese paper is very strong whilst being very lightweight. Wheat starch paste is also strong but is easily reversible and does not discolour with age. The water stains could not be removed as the required treatment would be too harsh for the fragile paper and so they were left as part of the paintings' history.
No. 1 ‘Platycladus orientalis’ (650 x 345mm) before and after treatment viewed with transmitted light, showing tears repaired using thin strips of Japanese paper and wheat starch paste
A very distinctive problem concerns the pigment lead whitewhich quite often darkens on exposure to pollutants in the atmosphere, changing from white to black. Most of the watercolours had been affected in this way, although largely confined to the human figures, especially the faces. After careful consideration it was decided to treat the blackened lead white to re-instate the original image whilst also stabilising it by converting the black compound to a more stable white pigment.
No. 22 ‘Juniperus chinensis’ detail showing blackened lead white, before and after treatment
The watercolours were finally hinged into new window mounts enabling their safe storage in Solander boxes in the Wolfson Rare Books Room and can now easily be put into frames if required for display.
After treatment hinged into new window mounts
It was a pleasure to work on these charming paintings and to overcome the challenges presented by their fragile paper and pigments. The watercolours can now be accessed safely and can be exhibited to be enjoyed by others.
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