UV-vis absorption

UV-Vis absorption and steady-state fluorescence

The XRF analysis of the blue petals on the flowers in the foreground of the painting was indicative but not conclusive. The presence of Cobalt in the sample could indicate the use of Cobalt blue, Cerulean blue, Smalt, or a number of other blue pigments. The additional UV-Vis reflectance results confirmed the presence of cobalt blue, which at the time was seen as a less stable but cheaper alternative to the more expensive and traditional Ultramarine. Maclise’s economic selection of the commercially available Cobalt blue pigments had a reputation for turning green over time, but by 1840 artists’ suppliers such as Windsor and Newton were selling the pigment with a declaration that it was stable and permanent.