The restoration generates a careful observation of the work of art. Thus, on the basis of a personal old documentation, the piece of art indulges in all its form and composition. When the historical sources do not allow this, the analysis is more done from evidences, the general harmony that allow Marc Desvallées and his fellow ironworkers to get closer to the spirit of the original creator : it is necessary to be in resonance in order to “reinvent” what was done by someone else in his time, and always in compliance with the blacksmithing techniques of the period.