why cork bumpers on rotors suck

[bloke]

@LeMark and I were discussing this (water key corks and rotor bumper corks) and the truth of the matter is that cork sucks because it sucks. It sucks for the same reason that grenadilla oboe and clarinet wood sucks:
Supplies are very limited, demand is very high (as everyone’s child is from Lake Wobegon) and much of it today is crap.
Oboe cork pads are still the quality of what rotor and water key corks were - quite a few decades ago, but cost dollars each - instead of cents.
The cheapest acceptable ones - through which a technician will pick - are over two dollars each, cost to the technician. Super high-grade ones are double/triple/quadruple/more:

https://charlesmusic.com/shop/cork-pads ... escription

Rather than hundreds and hundreds of times being opened and closed (as with water key corks), oboe cork pads have to stand up to being beat down against wooden tone holes countless thousands of times - with strong human fingers, rather than very small gauge spring wire, and are expected to last for decades.
A few decades ago, clarinet players caught on, and pay premium prices to have their clarinets outfitted with oboe cork pads, which top-drawer technicians select oversize - and trim to the shape of clarinet pads.
Hard rubber rotor bumpers appeared about the time that premium cork started becoming expensive.
Cork - sold today as rotor and water corks - are - again - crap.

I use either oboe corks or synthetics on my personal instruments.

If I install crappy genuine cork, it is on school instruments - such as sousaphones - where I know the water keys are going to be bent anyway, and the nipples will soon be taped over with “band director tape”.

If you happen to know someone who is a really fine woodwind repairman and is trusted with high grade oboes – which means that they are required to have a supply of oboe cork pads on hand, ask to see a couple of those pads. The density and the quality are exquisite (consistently, plenty fine for water key and rotor bumper use), but they still pick through them and reject some of them.