Residual stresses from manufacture and subsequent stresses from repairs appear to be the cause of cracking and crazing in brass instruments. This stress corrosion has been identified as such since 1900. When more modem instruments are treated by annealing the work-hardened metal, they are no longer subject to these stresses. The annealing procedure will not work with older instruments, however, since their soldered joints would not hold at these annealing temperatures. The mechanics of the stress corrosion are explained. Procedures for caring for brass instruments are listed. -- AATA