I have one of the original M&E polymer flutes. I don't know if they were delrin way back when they were first introduced. It has no cork, no rings and a metal slide. After using it as a car flute for a couple of years I ran it through the dishwasher. The material went from a pure black to a grey. But I didn't worry about it too much. I still have around and use it now and then.

"Dear Messrs. Firth, Hall and Pond...." (Oh, never mind)

Best wishes.

Steve

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"Do not resent growing old. Many are denied the privilege."

ebonite maybe

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Choose you this day, whom ye shall serve