Justus Sustermans’ Portrait of Cosimo III de’ Medici as a Child in its Final Stage of Restauration

Last month we outlined the initial phase of the restauration of Justus Sustermans’s Portrait of Cosimo III de’ Medici as a Child (1649). The treatment has since reached completion. After the removal of the degraded varnish, the work progressed to structural interventions aimed at correcting long-standing distortions in the canvas.

Child portrait of Cosimo III de’ Medici by Justus Sustermans (1649), shown in the initial pre-conservation phase, with yellowed varnish and visible canvas distortions.

Local adjustments were first attempted. Although these reduced the undulations, the overall tension of the canvas remained insufficient. It was therefore decided to remove the painting from its stretcher and apply a strip-lining to all four edges.

The painting then underwent planification to relax the canvas fibres, allowing for an even and secure re-tensioning on the stretcher. This treatment eliminated the planar distortions and resulted in a considerable improvement in both the appearance and structural stability of the work.

Reverse of a painting prior to conservation, showing a severely damaged poplar-wood stretcher with termite traces, cracks, and deformations that contributed to distortions in the canvas.

The original poplar stretcher proved to be in poor condition, marked by termite damage, cracking and warped elements that had likely contributed to the earlier deformations. A new, purpose-built stretcher was therefore commissioned, following the construction of the original.

Detail of the damaged poplar-wood stretcher prior to conservation, showing visible termite traces, cracks, and deformed elements that affected the stability of the canvas.

The treatment concluded with the filling of losses, chromatic reintegration and the application of a final protective varnish. These final stages bring Cosimo’s features back into focus, highlight the refinement of Sustermans’s technique and ensure the work is structurally safeguarded for future preservation.

Child portrait of Cosimo III de’ Medici by Justus Sustermans (1649), shown in the final stage of conservation, before the filling of losses, chromatic retouching, and the application of a final varnish.

Child portrait of Cosimo III de’ Medici by Justus Sustermans (1649), shown after completion of conservation, with restored paint layers, completed retouching, and an evenly applied final varnish.

Curious about the first phase of the restauration process? Read the full article here: Behind the Varnish: The Child Portrait of Cosimo III de’ Medici.