That's worth a try. I did find a couple more references to this phenomenon, and it appears that no matter what I try, I may be SOL:
"My understanding (and as I am not very familiar with meads, it wouldn't surprise me to learn I was wrong) is that grape wine and mead both have a hard time keeping co2 in solution (ie you can carb it, but as soon as you open, a gush will spring forth and little co2 stays in solution)
. This is one reason that true champaign takes so long to make: the wine stays on the lees for an extended period of time. Something about the breakdown of the dead yeast fortifies the solution with a substance that helps keep co2 in solution."
"Forcing a wine to hold carbonation can be challenging to say the least
. It's the only thing in wine/mead making that has made me upset enough to stand there cussing.
That's one reason that Champagnes get all that lees aging - the mannoproteins and other whatnot that are released as the yeast undergo autolysis help hold CO2 in solution. You can either do lees aging, or you can use a big dose of a product like biolees and that may help. I've read that gum arabic also can help - I just got some but haven't tried it yet."
My hunch is that there is some other factor that I'm bumping up against. I guess I should have paid more attention in Physics and Chemistry classes...