Researchers are currently analysing minuscule paint samples from The Night Watch. In an image of one of the paint cross-sections you can see various bright yellow and orange particles that Rembrandt used to paint parts of the golden embroidery of Willem van Ruytenburch’s buff coat. These particles contain arsenic, which is very toxic.
Researchers of the Rijksmuseum had previously discovered arsenic-containing pigments in the palette of Rembrandt, but not previously in the way Rembrandt used these arsenic pigments to depict the golden embroidery.
The question is now is which type of arsenic pigment did Rembrandt use in The Night Watch. Is it the more commonly known pigment, yellow orpiment (As2S3) or the orange/red realgar (As4S4), or were there possibly other variants? Chemical analysis using Raman spectroscopy can help answer this question.
The paint sample
Craquelure is commonly found in paintings and is a pattern of cracking visible on the surface. On The Night Watch we find different types of cracks. Cracks form in response to mechanical stresses due to natural aging, uneven drying of the paint or from mechanical impact.
In The Night Watch the cracks formed due to aging are typically deep cracks with sharp edges and square junctions. These are visible for instance in the dark background. The density of the age crack pattern varies from area to area depending on the nature, number and thickness of the paint layers.
Drying cracks are also visible, such as in the dark paint added to modify the contour of the drum and have formed due to uneven drying between the dark paint and the paint layer below.
Craquelure
This is not a screenprint by Andy Warhol, but an image made with data from reflectance imaging spectroscopy (RIS) scanning. The bright colours in this false colour image reveal the use of different colour mixtures that Rembrandt used for the boots of Willem van Ruytenburch.
Although yellow earth predominates (salmon-yellow-lime coloured areas in the RIS image), Rembrandt also used red lake, mainly for the shadows (pink-purple areas in the RIS image). RIS shows that the dyestuff for the red lake is made from scale insects.
The research team is still looking for other types of red lake, such as Brazilwood).
