Infrared reflectography (IRR) makes visible underdrawings or changes in paint layers that are not apparent to the naked eye. In the IRR of The Medici Holy Family can be seen cartoon transfer lines, freehand underdrawing, and a wash-like substance applied to the panel (all prior to the paint layers). Andrea made numerous changes to the composition between the initial cartoon transfer and the completion of the painting.
A comparison of the face of St. Elizabeth in the drawing with the IRR and painting shows that in the cartoon the preparatory design was drastically simplified to essential lines. In the painting stage, the artist further modified the face to present a woman apparently younger than the model he had drawn on paper.
The IRR also reveals that Andrea composed the figure of the Virgin by combining portions of two cartoons previously used for other projects. In this economical workshop practice, the artist synthesized new inventions by reusing and combining old designs.
IRR of The Medici Holy Family; photo Roberto Bellucci