Martyrdom of Saint Catherine

In autumn 2014 restoration work began on the Martyrdom of St. Catherine, by Gaudenzio Ferrari (Valduggia? c. 1477/80 – Milan 1546). It is one of the most important works from the last activity of the painter, who moved from Vercelli to the Sforza court in Milan, where he worked until his death.

The work was made around 1540-1543 for the Gallarati chapel in the old Franciscan church of Sant’Angelo in Milan, decorated by Ferrari on commission from brothers Francesco and Giulio Gallarati. In 1551 the church was demolished and the frescoes were lost, while the altarpiece was transferred to the family chapel in the new church of Sant’Angelo. In the early 19th century the work was replaced by a copy and passed into private collections, to be finally purchased by the Lombardo-Veneto government and donated to the Pinacoteca di Brera in 1829.

Before the intervention, the painting underwent a thorough photographic and diagnostic campaign, including radiography, infrared reflectography, infrared false color, ultraviolet fluorescence, X-fluorescence, colorimetric and Raman spectrometry, and seven stratigraphic sections (fig. 2). The diagnostic results and direct observations of the work have deepened our understanding of the artist’s technique, allowing each phase of the restoration work to be set up.

Painting technique

The board measures 331 x 210 cm, and consists of five vertically arranged poplar planks (Fig. 3). The planks are joined with a tongue-and-groove joint, and the joint lines are reinforced by butterflies. It is assumed that there were originally three sliding crossbeams in the thickness of the plank, positioned one in the middle and two at the ends of the plank, which were later modified.

The preparatory layers are light-colored and rather thick, formed by gesso and animal glue. The pictorial film obtained with oil technique is compact and full-bodied in the broad backgrounds and highlights, while it is fluid and transparent in the glazes (fig. 4).
Analyses revealed the palette employed by the artist: whites are always obtained with white lead (lead white); the complexion of a character on the right is made with white lead, yellow ochre and grains of cinnabar, while the red of the angel’s robe with Kermes Lacquer. Lead and tin yellow and pararealgar were found in the yellow of the vest of an executioner on the left, while the blue/brown stripes of his breeches are composed of azurite and red ochre; the green of the curtain at the top consists of verdigris, azurite and white lead. The natural varnish present on the surface before restoration (dammar or mastic), was not original. The work is currently presented in a gallery frame, made of molded wood and gilded with gold leaf.

Previous restoration and state of preservation

The numerous traces of alterations on the back suggest at least three major interventions on the support, two of which were confirmed by the discovery of archival documents and dated 1835 by Draghini and 1968 by Ottemi della Rotta.
The first intervention prior to those documented saw the removal of the original crossbeams and the application of a large frame divided into squares (grid), glued to the back with animal glue, with the aim of obtaining a completely flat pictorial surface and blocking any movement of the wood. Such a rigid structure produced further cracking of the wood and lifting of the color.

In the 1835 intervention, the frame was removed, the wooden butterflies were reinforced (fig. 5), and the system of crossbeams, four along the height, was reintroduced; in 1968 Ottemi della Rotta performed a simple revision of the system. The structure could not contain the tendency of the planking to deform, and new cracks were created.
The pictorial film has also undergone at least two complete cleanings over time, in addition to several localized interventions.
Prior to the current restoration, damage from previous handling, restoration, and careless cleaning was evident. Cracks, lifts and color gaps were visible on the pictorial surface. Extensive repainting, patination, and overlapping layers of paint were employed to conceal the abrasions, which had particularly depleted the green and red backgrounds.

Restoration work

Restoration began by cleaning the joint lines between the axes, to allow for color control at the fractures and to enable correction of any misalignments (fig. 6). The most delicate areas were protected with Japanese paper varnishes before proceeding with the work on the support.
The crossbeams were removed, and the back of the painting was cleaned of glues and other residues. The wood was treated to prevent woodworm and reinforced in the most fragile parts. The new support system consists of three crossbeams, shaped according to the curvature of the planking and secured to the support in an elastic and controllable manner by steel pins and springs.

Having concluded the intervention on the wood, the restoration of the pictorial surface has resumed, with the stopping of color lifts. The cleaning was carried out with solvent mixtures designed to remove the overmixed substances while respecting the original materials, and proceeded gradually and selectively, also in view of the uneven state of conservation of the work (figs. 7, 8). The reintegration of the gaps was carried out with watercolor and varnish colors.

Upon completion of the restoration, the painting was relocated to Room XV in the Pinacoteca’s new layout (figs. 9, 10).