The Musée de la musique in Paris conserves an important collection of brass instruments, which is often displayed, loaned out or played. The manufacturing techniques used to create these instruments, in particular their plating, are not well known and are rarely documented. Using specialized observational techniques, the authors have revealed several types of data that will help to identify the manufacturing techniques used for this type of instrument in the future. These instruments need regular conservation or restoration. For this reason, the authors compared several different protocols that have been used. The results are discussed with respect to the current state of the instruments and the conservation-restoration treatment formerly chosen. An evaluation grid is proposed to help conservators and restorers choose among potential conservation treatments for brass instruments. Finally, specific maintenance protocols are identified that respect the instruments' playing mechanics, the specific features of the corpus and the ethics and standards of conservation-restoration deontology.