In 1831, a document described the painting as “severely damaged by time, and by old restorations”. One of these restorations must have occurred after the death of the client, in 1651, and had resulted in an increase in the height of the canvas by about 13 centimeters, with relevant consequences: the juxtaposition of the two supporting elements had loosened the stability of the work, with inevitable fallings of some paint; the creases of the curtain in the background had been interpreted as lances with incongruous points; the colours had been weakened by brownish paint, in the impossible attempt to make the surface homogenous.
The preservative restoration of the Martyrdom of St. Orsola, performed at the Istituto Centrale di Restauro di Roma by Mr. Giantomassi and Ms. Zari, has added further points of substantial and sometimes exceptional novelty for an understanding of the painting. The research has allowed in the first place to recognize with certainty the hand of Caravaggio on the painting. The mixture used for the preparation of the canvas is very similar to the one used for the San Giovanni Battista, now at the Galleria Borghese, of the same period; moreover, the layers of the preparation are left visible in the shadowed parts, according to the typical procedure of the artist’s later period; the light sketching brush-strokes straightforwardly set the volume of the figures, the chiaroscuro effects, the proverbial light refractions; the execution of the flesh pinks employs few chromatic hues to obtain the modelling; no traces of a preparatory drawing are to be found on the canvas, nor of after-thoughts.
The investigations have not stopped with the confirmation of the autorship, however, but have also brought back to memory the tormented vicissitudes of the painting over the centuries; this is a work which has suffered a lot, practically from the very moment of its completion. The restoration work has brought the canvas back to the original size – the seventeenth-century addition of 13 centimeters has been located in a space in the back, still within the same frame. It has also let a decisive iconographic and pictorial detail reemerge; it has given back to us a set of colours less limited than the received one; and it has integrated the pictorial lacunae, by means of completely removable materials.