Here is a question from one of our customers purchasing a Yamaha Baritone Horn.
“I bought a Yamaha baritone from you around last November 2016. I think it was and I have been disappointed to notice corrosion starting quite fast on the slides. The worst has been in the picture which happened after only a week of not playing it. I have a number of other instruments including a cheap Chinese baritone and none of them has this problem. Not really good enough for a supposedly quality instrument. What can you do about this, see pictures below? ”
Our reply from our bass wind technician Aaron Ebert
I wouldn’t label the above photograph as ‘corrosion’. It is purely discolouration due to the brass tarnishing. There’s no reason to be concerned, it’s pretty standard to see small occurrences like this even with new stock. Factors such as players body chemistry, types of valve oil/grease, humidity, storage conditions etc. all contribute to the occurrence.
It would be superfluous to remove it as it has absolutely no effect on how the instrument performs or its condition. Continuously removing the discolouration by polishing the brass would actually lead to more issues over a long enough period of time.
My only concern is that even after cleaning it, or even with another instrument, the same discolouration will be present again. I would just grease the slides nice and evenly, and make sure they continue to run smoothly without any binding. Oxide build up which is white, green, or blue hues is what you don’t want on these surfaces.
I can’t explain why a 40 year old student trumpet shows no signs of this discolouration, but I do admit I have sometimes seen surprisingly clean examples from this period. Sometimes the inside slides are bead blasted on the early Yamaha instruments which may help with their resilience.. Nickel silver inside tubes are also more resilient to this discolouration, but ultimately it makes no difference.