Looking at the jacket of the shooting musketeer standing to the left of Banninck Cocq, you notice something strange with the colours (Fig. 1). The light part of the jacket shows loose brushwork in pale blue and purple hues. The shadow part, however, is a murky brown with little detail. To investigate this, researchers from the ONW team took minuscule paint samples from both light and shadow areas. The samples were embedded in small blocks of synthetic resin and polished to reveal the build-up of the paint layers. The exact composition of the paint was then determined using microscopic analytical techniques.
The ‘brown’ paint of the jacket was shown to contain mostly smalt (about 75%), with a small amount of red lake, lead white, and bone black (Fig. 2). The originally blue smalt has lost its colour due to a chemical reaction whereby potassium leaches from the glass. The red lake has also faded and the lead white has become transparent. To get an impression of what the paint might have looked like when freshly applied, Master students from the Conservation & Restoration programme at the University of Amsterdam made paint reconstructions based on the composition found in the paint samples (Fig. 3). The addition of a small amount of red lake and a tiny bit of black and white to the smalt, to reconstruct the shadow area paint, resulted in a remarkably dark purple tone (Fig. 4). Could this be correct?
To help us to understand the right colour balance in the shooting musketeer’s jacket we looked into seventeenth-century paint recipes that describe how to make purple. Theodore Turquet de Mayerne (1573-1655), a medical doctor at the court of James I in London, where he met many painters, wrote one of the best-known treatises in 1620. In this treatise, we find some interesting recipes for purples that are indeed composed of smalt, red lake and some black. Lead white was added to make a lighter purple hue and the amount of smalt could be varied to make the tone more blue or purple. Several recipes even prescribe this mixture for painting a purple velvet, possibly the material of the shooting musketeer’s jacket. Interestingly, De Mayerne explains how smalt with red lake and a little black works very well for the shadows, although, as he states, the latter may be left out as ‘smalt and red lake are quite “black” already’, just as we have seen in the reconstructions. Rembrandt seems to have used a mixture for his purple paints that was quite standard at the time, and that, indeed, the murky brown in the shadow of the musketeer’s jacket was originally a very dark purple.
