Giving It Gas
I see a lot conflicting info on degassing. I use the three prong drill attachment. Usually I go on for a minute then off then on then off and sometimes keep it going for 5 minutes straight, while changing the direction of the drill. Then I let it rest until the next day, where I do the same thing, but for a shorter while.
Should this be enough degassing?
Degassing is one of those things that seems like it should be really easy to accomplish, but in practice it’s one of the most vexing areas of kit winemaking, to both amateurs and experienced vintners alike.
The important thing to keep in mind is that when you use an implement to degas your wine, whether it’s a spoon, a drill-mounted thingy with flappy paddles, or (my choice) the three-pronged Wine Whip, you shouldn’t ‘stir’ your wine kit. Stirring merely moves the wine around, like a lazy kid on a merry-go-round. You need to agitate the wine hard enough to get all the gas out.
If you’re going to use a Wine Whip the top goes into the chuck of a high-speed reversible hand drill (plug-in kinds are best–battery jobs always seem to be flat when you need them) and the three prongs are folded and inserted into the carboy or bucket. When you’re de-gassing always use the whip at full power, except at the very beginning, when you test to see how much gas saturation the wine has. Everything is fun and games until you’ve got a heavily saturated wine turning into Krakatoa Cabernet and fountaining out of the carboy and onto the ceiling.
Sequence goes like this:
- Quick, one-second experimental stir. If things don’t instantly spray out of the carboy, proceed to step two.
- Go absolutely full power and keep it there.
- When the wine begins to swirl up the sides of the carboy, looking like it’s going to overflow, immediately reverse direction and go full power against the flow of wine.
- You’ll see the wine stop climbing up immediately. Keep it on full until it starts to climb up again, and repeat the reversal–full power.
- Repeat this twice more, always full-on.
The point of intense agitation is to cause tip-vortex cavitation in the wine, at the tips of the whip. Cavitation happens when you vaporize a liquid by exposing it to decreased pressure. This vapor is the same thing as steam from a boiling kettle, but doesn’t involve heat–just the pressure reduction.
This is a little hard to visualize, but it obeys the laws of thermodynamics perfectly. The most common place to see cavitation is in boat propellers. Spin them up too fast and they won’t push the boat, because they’ll be in a cavity of water vapor, whirling about and doing nothing.
If you’re old (like me) or a fan of classic cold-war movies, there’s a great example in the 1990 movie The Hunt for Red October. It’s a techno-thriller about Soviet-era espionage and features Sean Connery as a Russian sub commander with a ridiculous Scottish lisp. In the fateful scene, the commie sub tries to make a run for it but the propellers spin too fast and they cavitate. Why this is a crucial plot point is that during cavitation, when the vapor bubble collapses (as all good bubbles eventually do), they slam shut with such violence that they ‘hammer’ the water, which makes a large enough noise to alert enemy sonar operators.
Precisely the same thing happens in your wine when you stir fast enough with the whip: the bubble collapses, and as it does, you can see the intense shock wave that the collapse produces. And it hammers so hard, it rebounds and produces a secondary shock as well! It’s this slamming/hammering effect that literally blasts carbon dioxide bubbles out of suspension, and why stirring any slower is almost useless for de-gassing.
Keep in mind that this really only works with your three-prong whip. It’s purely a functional thing–the other models work, but they’re not quite as effective. First, most of the other whips cannot take the force of being reversed under full power. Their stubby little blades shear right off, or the hook-ish shaped ones twist themselves into a knot.
Second, if it’s the speed of the tip of the whip/propeller that makes the vortex appear, then spinning a set of three whips spanning a circle nearly a foot across at the same RPM as a wee stubby little set of blades will make those long whip-tips travel immensely faster–they must cover the same complete circle as the wee little ones, so they’re hustling much faster.
I hope this helps. Now pull out your whip and give your wine the gas.