Not all the construction stages of a great bronze sculpture may be deduced from observation of the finished work, most of all when it is not possible for the internal surfaces to be examined, where indelible chasings testify to various production stages, and as in the case of the Germanico, where the plaster of the reconstruction process occupies much of the interior space. However, it proved possible to pick out the signs of the metalworking: a lost-wax technique with the indirect method, calling for the use of foundry waxes and the welding together of the separate parts.
The methodology adopted for the restoration of the Germanico was based on the results obtained from the preliminary chemical and physical studies. The main aim of the intervention consisted in recouping the original bronze surface, which bore more signs left by the hand of the artist than damage caused by corrosion. A solid and compact surface layer, aesthetically pleasing, in fact facilitated and exalted the overall ease of appreciation of the refinedness of the work.
First of all, a number of polishing tests were carried out, with a view to exploring the stratigraphic sequence of the sediments and of the by-products of the corrosion process, identifying the level of polishing that best highlighted and respected the original surface, that most full of informative and qualifying contents, most stable in terms of corrosion by-products and most aesthetically engaging.
Once the polishing process – carried out mechanically – was complete, and all (potentially damaging) foreign bodies deposited on the surface had been removed, the next stage was that of the inhibition of further corrosion which, because of the humidity present in the atmosphere, would settle on the bronze surface; the filling of small holes and gaps with plaster, and lastly the painting of the white surface of the gypsum, in order to differentiate it chromatically from the specific tonal qualities of the bronze and facilitate the interpretation of the work, thus distinguishing the repair work from the original.
The intervention was carefully documented, using both photography and videoendoscopic footage, chemical and physical analyses, in order to identify the composition of the metal alloy, of the deposits on the surface and of the patinas, and through the use of graphic mapping to determine both the original production technique and the 19th-century restoration process.