The four stories of the life of Saint Barbara (Saint Barbara Assisting in the Construction of the Tower; Flagellation of Saint Barbara; Saint Barbara Pursued by her Father; Beheading of Saint Barbara and Death of her Father) - are components of an altarpiece belonging to the same polyptych - were purchased in Italy between 1860-1870 by Barone Max von Heyl, then sold in an auction in 1930 by the antique collector Hugo Helbing di Monaco, and, finally, donated to the Vatican Museums in 1935 by Joseph Clemens of Bavaria.

Dated between the end of the fifteenth and the start of the sixteenth century, the four small panels are works of the senese painter and miniaturist Guidoccio Cozzarelli (1450-1517), born in a family of artists, a pupil, and collaborator of Matteo di Giovanni. They constructed an extraordinary testimony of the painting in Siena during the transition between a culture that was still late Gothic and the early Florentine Renaissance, demonstrated by the effective, stylistic, and iconographic synthesis between a narrative and decorative approach that was still medieval and the use of the Renaissance central perspective that derived from the theories of Leon Battista Alberti and its practical application in the works of Brunelleschi, Donatello, and Masaccio.

The three panels arrived on December 15, 1935, as a donation from Joseph Clement of Bavaria to Pius XI. These panels had an intervention that included the smoothing of the curves with steam, thinning of the boards and construction of the containment system with brass squares.

Imaging Analysis
Restorers used X-Ray analysis, fourier transform spectroscopy, Raman spectroscopy radiography, and infrared reflectography. The photo below shows the localization of the Raman analysis points for the identification of the pigments and dyes used in the painting and for the retouches from the previous restoration interventions.

Shooting Induced Ultraviolet Fluorescence
In order to study the most superficial substances, and in particular those of an organic nature, the restorers analyzed the works with induced ultraviolet fluorescence (shots taken with Nikon D850, 105mm microlens, Kodak Wratten2B, and 85 optical filters). 130 shots were necessary to cover the entire painted surface of every single tablet.

Varnishing and Restoration of the Support
Restorers varnished the pictorial surface with Klucellin Acqua to protect it during the restoration of the support. They freed the boards from the metal elements that made up the old and no longer effective containment system.

Renovation of the Support
Once restorers removed the wooden elements, they fixed the support by inserting poplar wood wedges in the cracked areas, giving a more natural curvature to the paintings. They made four frames with a central crossbeam with the gluing of poplar wood sheets, suitably shaped according to the curvature of every single panel.

New containment system
The new containment system, lighter and more functional, required the insertion of brass elements glued to the support with Aralditeepo127. Nails in nylon provided a precise adjustment of the necessary forces to contain the movement of the wood.