This contribution deals with the study of the gelatine molding technique, as a fundamental moment of the multidisciplinary analysis that precedes the restoration of the cast of the Brivio Monument, which is preserved at the Academy of Fine Arts of Brera. The research aims to understand the mechanisms of decay directly related to the technical process, in order to plan the intervention, involving the identification of technical defects characteristic of the surfaces, the consultation of specific handbooks and manuals, the search for archival information and is put into effect at the "Gipsoteca Fumagalli & Dossi" in Milan, which is heir to a tradition directly connected to the workshop where the cast - object of this study - comes from: the Campi Museum. The recognition of the relationship between this cast and the same one at the Cast Court of the Victoria & Alber Museum is of fundamental importance.