My son is using a family cornet which was made around 1970. It was only used gently for 4 years in the 70`s and then stored in a basement and crawlspace, where the case also got wet. The case smelled awful and has since been replaced as too much water damage/mildew from storage. But the cornet looked to be in mint condition. It really looked new in September. By the end of October, lots of lacquer had suddenly come off. The shop that overhauled it in September is checking to see if they used any chemicals on it in the cleaning process. One person at the shop said they did use chemicals and one said only soap and water is used. Also, a neighbor had me use an air purifier type machine on the old, smelly case in September or October which we then stored the cornet in for weeks before we got a new case. I`m wondering if anyone has any experience with either of these causing a seemingly mint condition older brass instrument to get so much brass or lacquer damage in 3 to 5 weeks?