3. Analysis of smalt pigment color loss in paintings from the 16th to the 18th century

3.1 Introduction of smalt pigment

For a long time, smalt was considered the first synthetic cobalt-based pigment; since then, Amarna blue, an aluminate ancestor of Thénard blue, has been considered. It first appeared among the Egyptians around 1400 B.C. . However, smalt is thought to be the first European pigment derived from this metal. The first origin of cobalt ore was the Middle East, followed by Saxony with ores such as skutterudite or smaltite, which also contained arsenic, nickel, silver and bismuth. Heat treatment aims to convert these...