In 2022, the State Library of Western Australia acquired a series of six watercolour portraits of John and Sophia Gregory and their four children, Elizabeth, John, Eliza and Mary. They were painted between 1828 and 1829, prior to their departure from England on the sailing ship Warrior, which landed in Fremantle on 12 March 1830.
These artworks are among the first portraits to arrive in Western Australia. Recent XRF analysis of these portraits revealed new information about the works.
For example, the paintings were initially catalogued as having gilded frames, although no trace of gold was found during analysis. A strong peak of copper suggests that the frames were instead painted with a copper-based paint. Additionally, the paint has been applied over areas of damage and was therefore added to the frames well after they were made.
During the analysis of the portraits, varying levels of arsenic were also identified in nearly every sample area. Initially this was assumed to be the result of arsenic-based pigments. However, arsenic was also present in unpainted areas of the portraits, including on the paper backing applied to the reverse of Mrs Gregory’s frame.
XRF spectrum results of the gold-coloured frame, featuring a large copper peak.
Arsenic was a common ingredient in pesticides and preservatives used from the 18th to 20th centuries and was often used to treat taxidermy specimens. Although it was not usually used to treat paper-based works, given the evidence of pest damage on several of the paintings, it is possible that the portraits were treated with a pesticide containing arsenic to prevent further pest infestation.
The paper backing on the reverse of Mrs Gregory’s frame. Visible pest damage is present throughout.
Due to this analysis, the object descriptions can now be updated with the correct descriptions of their materials, and appropriate health and safety procedures and new handling guidelines will be implemented to mitigate risk, to protect both staff members and the public.