I am located in Europe and looking for someone to do a routine clean on my horn.
What kind of cleaning do you recommend and what would you stay away from?
If the shop repairs all kinds of instruments, is it pretty safe to assume they know what they are doing with a [F]rench horn, or do I need to look for someone that specializes in horns?
Any shop that can do a good cleaning of brass instruments should be able to do a good cleaning of a horn.
That being said, you don’t want your horn to be the first horn the technician has ever worked on. Horns present unique challenges in terms of disassembly and reassembly, mainly related to the nature of rotary valves. The good news is that in Europe rotary valves are far more prevalent than in North America, mainly because many more trumpets have rotary valves. Most brass technicians there should be comfortable with working on rotary valves.
As for the kind of cleaning, there are two methods that I recommend: the traditional acid cleaning and ultrasonic cleaning.
An acid cleaning consists of the following steps: disassembly, parts degreasing, acid washing, rinsing, acid neutralization, final rinsing, parts drying, and reassembly. The acid used can be various types, but most common is a solution of hydrochloric acid. The acid dissolves surface corrosion and hard build-ups.
An ultrasonic cleaning uses sound waves to remove surface deposits, and replaces the degreasing and acid washing steps. Because it usually involves a solution that is mildly acidic, I recommend not skipping the acid neutralization step in an ultrasonic cleaning.
I would only want a technician who does all the steps I’ve outlined, so ask the technician about the steps they use and ask other players about their experiences with the shop in question.
What you get with a horn specialist is expertise in the disassembly and reassembly steps, and someone who is skilled in looking for other horn-related problems.