Lead(II) Formate in Rembrandt's Night Watch: Detection and Distribution from the Macro- to the Micro-scale

Area of Science:

• Art Conservation Science
• Materials Science
• Chemistry

Background:

• Rembrandt's "The Night Watch" (1642) is a masterpiece housed in the Rijksmuseum.
• X-ray powder diffraction (XRPD) mapping revealed an unexpected lead(II) formate compound in the painting.
• Lead(II) formate has not been previously identified in historical oil paints.

Purpose of the Study:

• To investigate the presence and formation of lead(II) formate in "The Night Watch."
• To explore potential chemical pathways for lead(II) formate formation in 17th-century oil paint recipes.
• To understand the reactivity of lead driers within oil paint matrices over time.

Main Methods:

• X-ray powder diffraction (XRPD) mapping at multiple length scales.
• Preparation and micro-analysis of model oil paint media using historical recipes (linseed oil and lead(II) oxide drier).
• Synchrotron radiation-based micro-XRPD (SR-μ-XRPD) and infrared microscopy for micro-scale compound identification and mapping.

Main Results:

• Lead(II) formate was identified in multiple areas of "The Night Watch."
• Model oil paint samples revealed the formation of both lead(II) formate and lead(II) formate hydroxide.
• These compounds were successfully mapped at the micro-scale in the model systems.

Conclusions:

• The study provides a potential chemical pathway for the formation of lead(II) formate in historical oil paintings.
• The reactivity of lead driers in oil matrices is further elucidated by these findings.
• This research offers new insights into the degradation and transformation processes affecting Old Master paintings.