Meanwhile, I would still like to know where the advice on the other side is coming from
Rob,
While it is certainly eminently reasonable to speak from years of experience in performance of a trade, at times the blind adherence to tradition can get us to miss the potential for improvement. In the flute field the relatively rapid evolution of design of the simple system conical flute in the 18th to 19th century is good evidence of this. After all we wouldn’t have tuning slides at all if the early classic Baroque style flute had been termed “good enough” because that was the way it had always been done (not to say that Baroque flute don’t have their place).
If you are actually interested in knowing where m31 is coming from, instead of just dinging him for not being an instrument maker, he, who I’m sure can speak for himself, is referencing a well know phenomenon called electrochemical corrosion. This will take place, to a certain degree whenever there is a significant flow of water containing gaseous oxygen, which all water does, in or around a pipe line where two dissimilar metals are in direct contact. You may have seen it yourself at the connection to a domestic water heater where the copper house distribution lines are improperly tied directly into the steel water heater (now dielectric fittings, which have a plastic barrier to direct metal contact, are used to prevent this and save our heaters, but that is another story).
His recommendation was for a new flute maker, not one with hundreds of flutes under his belt. It was well meaning, even if a bit misguided. Where he went wrong was in discounting the relatively minimal quantity of fluid flow inside a flute, the proximity of brass (basically an alloy of copper and zinc) and nickel silver (an alloy of copper and nickel, often with an addition of zinc as well) on the electromotive-force series of metals, the action of the slide lubricant, the corrosion proofing characteristics of zinc and similar alloy additions, and the polish of the metal tubing used for the slides. Even with all of these, if a slide made of two dissimilar materials were to remain in direct contact over a very long period of time, in a particularly humid environment, there is a chance for corrosion to freeze the slide. As stated above, and by others, it is more likely with metals that are further apart on the electromotive-force series (like silver and chrome steel for example).
I am certain that Gabriel’s slides, as described, will function as needed for the lifetime of the flutes, and am in no way questioning their design. The flutes are lovely and from his clip they sound as good as they look. It is great to see another craftsman making instruments. I’m quite jealous as I’ve enjoyed doing some restorations, but not taken the plunge to manufacture.
