I've been a tech for 35 years. I use my chem bath on my own horns, including my Eclipse MR, and the horns of various pros in the area. I've never had any problem with it. Okay, well, I did have one. In the early 80's I put a Mexi-Conn french horn in my vat. When I pulled it out, the lacquer slid off it. Scared the $h*# out of me. I wound up relacquering their horn. Told them what happened. The horn looked better than before, and played better, so no problem. I will not put my 1939 40B in the vat. I am afraid that the inner mouthpipe has some badly corroded spots, and the acid might clean out the corrosion and leave holes. But for any horn that is not in danger of that kind of rot, it is fine.