Assessment of George Stubbs’ Portrait of Joseph Banks

By the mid-1760s, George Stubbs had matured as a master of human and animal painting. One example is his large oil-on-canvas portrait of the great botanist Joseph Banks on his inheritance. Electron microscopy with atomic scatter was carried out on a sample of paint and varnish from the edge. This demonstrated iron, calcium, carbon and oxygen ratios such that Stubbs must have used Black Ivory and Burnt Sienna color pigments in a nine-to-one ratio for his dark brown background. The absence of wax globules substantiates the received wisdom of Stubbs commencing its addition from 1767 and matches the date of the portrait being shortly after Banks’ 1764 inheritance. Stubbs was observed to have used evenly plasticized linseed varnish without lead drying agent or markedly carbonized burning. This was of high quality compared to a varnish applied on relining decades later. The same appearance implied pure linseed in Stubbs’ oil paint ground. Stubbs’ skill in art materials to a clear scientific degree reflects his academic ability as an anatomical scientist. These are inexpensive, new findings on Stubbs’ painting and varnish technique, with the potential to help conservators and researchers working on other important canvases by the great artist.