Historical Painting Techniques, Materials, and Studio Practice

Figure 5. Irifrared niflectogram assembly of the Virgin 's sleeve, showing the "correction" layer which
appears as dotted lines (area of refiectogral1l: 24 X 21 an). Refiectograph by M. Faries.
The paint layers
The preparatory layers. Staining the cross sections shows that the chalk ground
in the main panels was not coated with a layer of glue before application of
the underdrawing. In some of the cross sections, however, there is a dusting
of red and black particles in an oleaginous layer; these particles are especially
visible under the green cloth of honor behind St. Anne and the Virgin.
Scattered particles such as this are rarely noted in painting cross sections;
however, Coremans, et al. and later Brinkman, et al. found a similar layer in
the Ghent altarpiece (15, 16). There is a clearer indication of the use of a
sealing layer over the underdrawing in St. Anne's red drapery. Here the hatching
lines, which are visible to the naked eye, have a translucent layer over
them, separating the red paint from the drawing lines.
The X-radiographs of all six predella panels have clear indications for an
overall, randomly brushed underlayer which must contain lead white to register
in the X-radiograph. The few samples from the pre della panels show
Metzger and Berrie 131