The acid attack (1990) on Rembrandt’s The Night Watch (1642). Reassessing the painting’s condition through a multimodal analytical approach

In 1990, Rembrandt’s The Night Watch was attacked with concentrated sulphuric acid. This study reassesses the affected area and aims to identify and characterise any secondary degradation products, as well as any challenges for the conservation treatment. A comprehensive analytical approach, using macroscopic X-ray fluorescence (MA-XRF), macroscopic X-ray powder diffraction (MA-XRPD), optical coherence tomography (OCT), and light microscopy, scanning electron microscopy combined with energy-dispersive X-ray (SEM-EDX) analysis, micro attenuated total reflectance Fourier transform infrared (µ-ATR-FTIR) spectroscopy and synchrotron radiation micro X-ray powder diffraction (SR-µ-XRPD) of three paint cross-sections, permitted the confirmation of anglesite (PbSO4) and extensive lead soap formation in the affected areas. Additionally, mock-ups were prepared and analysed to reconstruct the entire sequence of events of the acid attack. Current estimations predict that some of the damage to the paint layers will become discernible after varnish removal and that local consolidation of the fragile surface might be required.