New evidence for the intentional use of calomel as a white pigment

Abstract

In this work, we report the results of the in situ application of micro‐Raman spectroscopy to the analysis of two historic painted objects: a 15th‐century illuminated manuscript and a late 16th‐century portrait miniature. Both objects were unexpectedly found to contain calomel (Hg<jats:sub>2</jats:sub>Cl<jats:sub>2</jats:sub>), intentionally used as a white pigment. Calomel was a widespread and popular medicine until it fell out of use at the end of the 19th century due to its toxicity, and a material called ‘mercury white’ is referred to in 16th‐century technical literature on painting. However, although calomel has been recognised in the past as a degradation product of cinnabar in both wall and easel paintings, its deliberate use as a pigment on cultural heritage objects has only been documented recently in white areas painted on 17th‐century South American objects. The present study describes the first ever verified use of calomel as a white pigment on European works of art, both of which predate its documented use in South America.