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Conserving Darwin's Letters

Eleanor Hasler
17 May 2013
Discover more about the conservation work carried out on one of the most important, popular and fascinating collection in the Archives.

Among the several million original items in Kew’s Archives is a series of 44 letters between Charles Darwin and his mentor, Professor John Henslow, which document Darwin’s travels on HMS Beagle. Written between 1831 and 1837 these fascinating letters show Darwin’s theories developing as he collected specimens and reported his findings back to Cambridge. The tone of the letters is very amiable giving an interesting and moving insight into Darwin’s experiences, an example being his excited reaction to being told he had been accepted on the expedition by Captain Fitzroy - ‘Gloria in excelsis is the most moderate beginning I can think of’!


Surface cleaning a letter


The letters were presented for conservation loose, having previously been taken out of their poor quality nineteenth century binding. Although the paper was a good quality, often large tears and losses were evident especially around the edges and wax seals. Various types of repairs had been added to the letters, and the paper tabs used to stitch the letters into the binding were still adhered to the letters, often obscuring the text. The main problem, however, was the degrading ink which was evident on all of the letters. Darwin had used iron gall ink – an ink which was used extensively throughout the nineteenth century but one which can, due to its components, ‘corrode’ the paper in and around the ink line.


Ink corrosion
Ink and paper loss due to ink corrosion.

Losses, as well as 'haloing' and 'strikethrough' of the ink were evident on the letters so stabilisation of the ink needed to take place in order for the writing to remain legible and to minimise further degradation of the paper support.


Ink corrosion on letter
Absorption of UV light indicates the presence of iron gall ink. The visible presence of writing on the reverse side, during UV light investigation, indicates a risk of future ‘strikethrough’ of ink, if left in its current state.


All of the letters needed surface cleaning, and previous repairs and tabs had to be removed prior to treatment of the ink. After slow humidification to minimise movement and stress in the paper, the letters were immersed into a water bath and then into an aqueous solution of calcium ammonium phytate. Deacidification then took place in aqueous calcium bicarbonate and the letters were subsequently re-sized with gelatin. This procedure stabilised the ink and allowed for the necessary repairs to the letters to be adhered. Losses were infilled using a toned Japanese paper and tears were repaired so that all the writing was legible.


Ink treatment of letters
A batch of letters in the first bath of cold water

The letters were re-housed in a specially designed folder which allows for each letter to be viewed without the risk of any further damage. This was a fascinating project which allowed me to investigate the best way to preserve these important letters for the future whilst respecting their unique history. Thank you to the several generous individuals who made the conservation of these letters possible.


Folder housing Darwin letters
Letters in the leather bound folder after treatment

- Eleanor Hasler -

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