Quick answer
- Finished wine is full of dissolved carbon dioxide (CO2). If you leave it in, the wine can taste fizzy and bitter, and corks can push out.
- The easy way is to rack the wine back into the open primary pail and stir hard.
- Stir 3 to 6 times a day for 2 to 4 days, or use a drill-mounted degasser.
Before wine goes into the bottle, it must be clear, stable and free of CO2. Fermentation produces a lot of carbon dioxide. Even after fermentation stops, the wine can stay saturated with it, like an unopened bottle of pop.
Why Degassing Matters
- Taste: leftover CO2 gives wine a prickly, bitter taste.
- Corks and bottles: trapped gas can expand later and push the corks out or even crack bottles.
- Clearing: fining agents work much better in wine that has been degassed.
Skipping degassing is basically how sparkling wine is made. Good for Champagne, not for your Merlot.
When to Degas
Degas at the stabilizing step, once fermentation is completely finished: an S.G. of 0.990 to 0.995 that stays steady for 2 to 3 days. If the reading is still dropping, wait. See How to Use a Hydrometer.
The Easy Way: Use the Primary Pail
Here is what most kit instructions don’t tell you. Rack the wine out of the carboy and back into your sanitized primary fermenter pail to degas it. It is much easier to stir hard in a wide-open pail than to shake a heavy glass carboy or work a spoon through its narrow neck. Carboys have been known to break during this step. The extra racking also helps the wine.
- Rack the wine into the clean, sanitized primary.
- Add the stabilizer packets (metabisulphite and potassium sorbate) as your kit directs.
- Stir vigorously with a long plastic spoon or paddle for a couple of minutes, until the foaming dies down.
- Repeat 3 to 6 times a day for 2 to 4 days.
- Then add the fining agent and move on to clearing.
Using a Drill-Mounted Degasser
A drill attachment such as the Fizz-X degassing and mixing tool saves a lot of arm work. Start slowly, because wine full of gas can foam up fast. Use it in the primary pail rather than a glass carboy, and keep the tip away from the bottom so you don’t stir up sediment.
How to Tell When the Wine Is Degassed
- Stirring no longer brings up a rush of foam or fizz.
- A sample shaken in a closed jar with your thumb over the top builds little or no pressure.
- A sample tastes flat, without any prickle on your tongue.
Frequently Asked Questions
How long does degassing take?
Usually 2 to 4 days of stirring several times a day. A drill-mounted degasser can get it done much faster.
Can I over-degas wine?
It is hard to overdo it. Just avoid splashing more air into the wine than you need to, and keep it covered between stirs.
What if I skip degassing?
The wine may not clear properly, may taste fizzy or bitter, and could push corks out after bottling.
Keep Reading
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This guide is adapted from the ABC Crafted Series booklet Wine From Kits: What the Instructions Don’t Always Tell You. Always follow the instructions that come with your kit.