The restoration of the most precious photographs preserved in the Archive of VenerandaFabbrica del Duomo has recently been completed. There are 410 positive prints produced with early photographic printing techniques, namely salt, albumen and wet-plate collodion printing, which can be dated from the mid-1800s to the first quarter of the 1900s. They were taken by leading Milanese photographers and provide crucial visual evidence of the Duomo’s architectural and artistic history.
The work was performed by a restorer specialised in restoring photographic and paper assets. She intervened on the original objects to eliminate factors that caused deterioration and to recreate the best conditions for their preservation and use. The prints have undergone several interventions designed to prevent the various types of degradation present in the different parts of the object, precisely primary support made up of photographic emulsion and paper, and secondary support (i.e., paper or cardboard), if present.
All the photographs were subjected to a dry cleaning process with dedicated brushes and rubbers to eliminate potentially abrasive and acidic surface deposits. The most delicate parts of the photographs, such as handwriting, embossed seals and photographic emulsion were processed with a special rubber called vulcanised rubber, which is used for buffing (as we can see on the cover page), while supporting cardboards were cleaned with rubbers having various degrees of hardness to eliminate the most resistant sediments.
Some photographs presented mechanical damage or folds, lacerations and deficiencies both on the primary support and on the secondary one. In such cases the restorer intervened by flattening the photographs, leaving them to rest under a weight, and later consolidating and suturing the paper support by applying veils of Japanese paper and cellulose-based adhesives. Another form of degradation was blistering of the emulsion, to prevent which the restorer consolidated the photographic layer with a dedicated alcohol-based adhesive.
Now that the corpus of the oldest photographs of the Duomo has been restored and image readability has been improved, the material is being digitalised to make it easy for researchers and scholars to refer to this important iconographic legacy.
The image shows an albumen print assembled on cardboard during an intermediate phase of the restoration process (Luigi Montabone, Croce di Ariberto da Intimiano, 1871), with alongside the tools and materials used for the work: vulcanised rubber, tweezer, surgical knife, roll of Japanese paper, brush and glue, vinyl putty rubber, awl, large brush with soft bristles.