My guess is Lacquer wont get damaged because it is a plastic. If you leave the vinegar on the horn for a while than maybe it will. I would wash with acid for only 30 minutes the most. I would not risk putting my whole instrument into vinegar. I would mix some vinegar with water tho and the vinegar shouldn't hurt the lacquer(not sure about silver/gold) I tried using vinegar and it worked. Metal polish works better but its hard to get it inside the tubing.