The problem of designing a particular restoration treatment for this sculpture related to the fragility of the material (plaster) and to the amount and variety of earlier restorations to which it had been subjected. In order to establish a correct and effective solution and in addition to the above-mentioned technical studies, exhaustive solubility tests were carried out in different areas to determine the products and cleaning techniques that would be most appropriate in each case.

The principal cleaning of the work was carried out using agar-agar gels, a product derived from different species of marine algae that form gels which retain large amounts of water in low concentrations. These gels have extremely powerful cleaning properties through the controlled application of moisture and absorption of dirt without the need for rinsing. Their use is therefore highly recommended for the application of aqueous treatments to delicate and partially soluble surfaces such as plaster.

The treatment was completed with various types of mechanical cleaning (India rubbers of different degrees of hardness and even the micro-projection of vegetable abrasives at low pressure). Chemical cleaning was also necessary in specific areas in order to remove stains and accumulations of previous additions to the surfaces. Mixtures of organic dissolvents were thus applied as strips with protective paper in between and the application time strictly controlled. The aim of these procedures was to restore a homogeneous appearance to the surface of the work, respecting the natural aging of the material used to create a sculpture that is now more than 100 years old.

In addition, all poorly executed areas of reconstruction were removed. Many of them were not fully attached to the original surface and had been reinforced with nails that had produced stains due to oxidisation. Following a criteria of minimum intervention it was decided only to reconstruct the fingers of Seneca’s right hand on a scale proportionate to the rest of the work, given that they are located at the work’s focal point and because they are important to the figure’s expressive powers and thus to the narrative being recounted. In addition, the original areas of polychromy have been left as they are in the present day, without touching the areas of oxidised metallic powder.

In order to recreate the fingers, the Museum’s restorers turned to the original, reduced-scale model now in the Museum in Zamora, from which digital data was obtained and enlarged to the appropriate scale. Old photographs that showed the work with the original hand still intact were also consulted. Reconstructed areas that harmonised with the work were retained.

Losses were filled in with gesso and were chromatically reintegrated using reversible materials such as watercolour and gouache and techniques visible to the naked eye such as pointillism and trateggio.