From another thread
This left me wondering, how many flutes use real cork for their cork? I always assumed that Most flutes had a hardwood plug wrapped in cork. Are their many flutes with just a cork and an end cap? Are there flutes with a metal face? (I assume that the plastic flutes have a plastic stopper.)
(And of course the unanswerable debate about does it matter? (Or, “should I glue a dime to the face of my cork” 
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Dear I.D.10-t,
I have replaced all of my corks with fitted hardwood dowels. I believe they increase the quality of tone and projection.
Corks are real in most cases. I buy mine from Ferees in Michigan, real cheap. A lot of experimentation has gone into stoppers, look up Robert Bigio on google and read what he has done, quite revealing. Terry McGee has done quite a bit of work on stoppers as well, I think. Google him too.
If you leave a metal or wood flute or Fife too long in a fairly dry place, without playing every day it will become harder to play because the cork will shrink and start to allow leakage. The low octave goes first. You can improve things by simply pouring water into the head joint and leaving it for a few hours to soak into the cork to expand it. The origin of the concept of pouring guiness into a wood flute I suppose.
I got my cork from a bottle of Warres port. The endcap is from a bottle of Balvenie scotch. 
I agree with Monkey on this one - half the fun is drinking through wines and ports until you find the perfect cork for your flute.
Jordan - you’re missing out on something with this!
Personally, I’ve not owned a flute with wood dowel lapped in cork - and as far as I know most of the players I’ve talked to have said they had to replace their cork one time or another so I assume they have cork, too. I have at times glued dimes to the end of the cork - seems to brighten the tone a bit, but I’ve come to prefer just the cork with nothing else on it.
Eric
Sillydill,
Please tell me more about these dowels, are they cork faced, or maybe O-rings? Made by you or somebody else?
My Mark Hoza flute has a small plastic stopper, it’s relatively thin and has an O-ring. My other flutes have natural corks, and I’ve never pulled them out to look. I know that I should for oiling…
Hoza uses the Biggio stopper with Roberts permission. I’ve contemplated buying one from time to time, but just never gotten around to it.
Eric
Reguarding the Hoza Biggio stopper, my Eb Hoza had a vibration sound discernable from the head of the flute. I didn’t like it and replaced the derlin button with a genuine Rosemont Estates Travernmeyer Reisling cork. This eliminated the buzz in the head.
As per “Accoustical Reverberation Wave Amplifiers” (aka. sections of wooden dowels). I use 3/4" beech rod, indescrimanately cut to over an inch length. The length is indescrimanate, not the face which is squarely cut with a miter saw. I then oil the plug and wrap it in plumbers tape to achieve a tight tollerance fit in the head of the flute. I have wondered about the effect of moisture accumulation between the dowel and flute head. But after a month of use, no adverse effects were discernable.
Dear Eric, while I may not currently use the corks in my flute, I none the less keep an ample supply on hand for emergencies! 
My Burns’ have wooden thingies wrapped in thread(not cork). I don’t really want to call them “dowels” because they’re made of mopane, which seems somehow too spiffy to go by the name “dowel,” but that’s really what they are.
So far, I have not been removing the cork to oil my flutes. I know, I’ve been bad. On the other hand, I am pretty sure I don’t have any leakage at the moment. I think a pretty good test is to remove the crown and try to blow into that end. A leak is pretty obvious.
I’m still tempted to try the hardwood plug, but I also tend to follow the “if it ain’t broke, don’t fix it” rule.