Time To Bottle, But My Wine's Still Bubbling!

My Glass Carboys Still BubblingHello Adventures in Homebrewing,
I have made wine from kits over 50 times with fantastic success!  I have always followed the directions and SG measurements of my hydrometer.  I was admiring a finished batch in one of the carboys, getting ready to filter and bottle.  To my surprise I noticed the airlock bubble!  I watched it and after 7 minutes it did it again.  The highly polished finished wine had no bubbling in it or from the lees.  Obviously there is some fermentation occurring.  Should I rerack the wine into a new carboy and add sodium metabisulfite or what????
Thanks Rich G.
Dear Rich G.,
Glad to hear you’re having such great success with all your wines. People can’t believe how great these wine kits are until they’ve actually tried them.
When it comes to making wine, a good mantra to follow is: When in doubt… wait.  Assuming you have a good finishing reading on your gravity hydrometer, I would not do anything but wait some more before filtering and bottling. Just give it more time to make sure the fermentation is complete. You could add a standard dose of potassium or sodium metabisulfite to the wine, but I don’t think it is necessary.
In reality, the fermentation may actually be done even though you are still seeing some bubbling. It could simply be some trapped, leftover CO2 gas from the fermentation that hasn’t been able to release until now.
Temperature change can play a role in this kind of occurrence. If the wine is in glass jugs of sorts, as the temperature cools the glass contracts making the volume it can hold slightly less. The result is a pushing out of some head-space. This is not too noticeable with gallon glass carboys, but when you get to the larger sizes –5, 6 and 7 gallons– it is surprisingly noticeable.
A rise in temperature can also cause some bubbling as well. As a liquid becomes warmer it’s ability to hold CO2 gas become less and less. This is evident when opening a hot can of soda pop versus a cold can. The amount of CO2 gas the froths out is quite different in each instance.
In any event I would just wait it out if I were in your shoes. There’s really no hurry to get the wine into bottles, and realize that the wine is still aging even while it is in bulk.
Great to hear from you.
Customer Service at E. C. Kraus
Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.

0 thoughts on “Time To Bottle, But My Wine's Still Bubbling!

  1. I have just started a batch of Merlot. The pail is covered with top although not sealed and it has an airlock. The airlock is bubbling non stop (percolating) and a bit of wine is spritzing out the sides. Why is this? Have we done something wrong?

    • Doug, you are not doing anything wrong, you just have a vigorous fermentation with a lot of foaming. Different juices foam differently. They also vary in the set of nutrients they provide for the fermentation. These nutrients can directly affect the wine yeast’s ability to ferment. Some wine yeast will foam more than others. It just part of their character.