Luminescence of coprecipitated titanium white pigments: Implications for dating modern art

摘要

Material analysis of cultural artifacts can uncover aspects of the creative process and help determine the origin and authenticity of works of art. Technical studies on abstract expressionist paintings revealed a luminescence signature from titanium white paints whose pigments were manufactured by coprecipitation with calcium or barium sulfate. We propose that trace neodymium present in some ilmenite (FeTiOsub3/sub) ores can be trapped in the alkaline earth sulfate during coprecipitation, generating a luminescent marker characteristic of the ore and process. We show that the luminescence is linked to a specific ilmenite source used in historic TITANOX pigments, is not present in pigments produced by more advanced chemistries, and provides dating information. Facile Raman-based detection of this luminescence, along with characteristic peaks of rutile, anatase, calcium sulfate, or barium sulfate, can identify the type of titanium white pigment and narrow its manufacture date range.