As black as she is painted
Vermeer seems to have used two different black pigments: charcoal and bone black. Sometimes he mixed them together. Perhaps he was trying to achieve a specific colour. Charcoal produces a bluish black, whereas bone black is brownish. The black pigments that Vermeer used in the Girl are mostly hidden beneath the surface, or mixed with other colours. As you’ll find out in a blog in a couple of days, the background of the Girl wasn’t originally meant to be black.
Charcoal is made by charring wood (usually willow or grape vines) inside a closed vessel in a fire. A charcoal stick can be used for drawing, but can also be crushed and mixed with a binding medium to make ink or paint.
[fig. 12e: sample 21 with charcoal]
This cross-section is from the background of the Girl, where Vermeer applied charcoal black as an underlayer beneath a translucent glaze. The splintery black particles are the charred wood fibres.
The other black pigment that Vermeer used was bone black. What is it made from? Bones, of course…but also animal horns or ivory. Because bones are mostly made of calcium phosphate, the elements calcium (Ca) and phosphorus (P) can be detected with the scientific techniques SEM/EDX and FIB-TEM. These particles are also usually rounder and smaller than charcoal splinters.
Vermeer used a mixture of charcoal and bone black in the underlayers beneath the clothing (which I’ll discuss in a later blog post).