How Long in Secondary?

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mhopkins

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I am doing a RJS South African Sauvignon Blanc kit (no skins). I started Primary fermentation with Bentonite, juice from kit, and rehydrated yeast from kit. SG 1.093. Instructions call for a move to Secondary after 6-8 days. I had to leave town on an emergency, so rack to Secondary happened after 17 days (YIKES!). Added oak chips to carboy during rack to Secondary. SG 0.99. Instructions call for 14 days in Secondary … then Stabilizing & Clearing (Sulphite, Posassium Sorbate, Kieselsol, Chitosan). But, I want to let the wine sit on the oak for an extended time – maybe 2 months; stirring occasionally to ensure greatest contact with the oak. My concern is that fermentation was completed during the extended time in Primary, so I likely have no CO2 cap sitting on top of the wine to protect it from oxygen (about a 3” diameter exposure in the neck of the carboy). Should I be concerned about oxygen exposure? Can I let it sit for the desired 2 months before Stabilization without concern for oxidation? Thanks for any insights! Mark
 
Until the wine is degassed, there is plenty of co2 Entrained in the wine to protect it... that whole co2 “cap” concept is a bit misleading as it has to a)settle there and b) but left completely alone to continue to exist. In reality if the wine is disturbed co2 gas will mix with the air, allowing contact of the wine with air until the co2 resettles over time. It’s more the entrained co2 filling the available gas volume in the wine that keeps the air out. If you have limited head room, there is a very small volume of air that encounters the wine in the first place. It seems rather low risk. Personally I think your plan is fine to continue before the rest, however If you are really worried, go ahead and rack it, stabilize and start clearing just move your oak chips over with the wine. Oaking after that is fine. If you a trying to sur lee then that’s different, but you don’t mention the lees.
 
that whole co2 “cap” concept is a bit misleading as it has to a)settle there and b) but left completely alone to continue to exist.

I agree with the bulk of Doug's message, but I would like to (once again, sorry) point out that there is no CO2 cap/blanket effect. Even if the volume is completely and utterly undisturbed. Gases freely mix after a few minutes. The final (equilibrium) distribution is an essentially uniform distribution of gases.
 
@sour_grapes i was trying to avoid poking the bear, but agree with you :n:n:n . Co2is slightly heavier than air and will gas will stratify if left completely undisturbered (ie not one bubble or vibration or temp change or ripple). If held completely still it will strife but will commingle at slowly deminsihing distribution levels as you move up the channel. Bottom line though, IMO a co2 cap is near impossible to maintain is a home wine making environment.
 
Forget the CO2 cap, I'd worry more about the lees. Extending the time on the lees, especially dead yeast cells, seems to be a gamble not worth the risk. Other than a red left on the grape skins on purpose, extending the exposure to the lees is a potential for issues you don't need, A simple airlock should sufficiently limit exposure to oxygen unless someone is opening the carboy daily. Once fermentation is completed, and you were almost there when you did the rack to secondary, what the point of leaving it on the lees. Off gassing of CO2 should be enough unless your volume of head-space is excessive and from your description is it not. It may not be optimal but lets not strain the gnat and swallow the camel.
 
Co2 is slightly heavier than air and will gas will stratify if left completely undisturbered (ie not one bubble or vibration or temp change or ripple). If held completely still it will strife but will commingle at slowly deminsihing distribution levels as you move up the channel. Bottom line though, IMO a co2 cap is near impossible to maintain is a home wine making environment.

No, I am sorry to say that it is not possible even in principle. The gases will not stratify (to any non-negligible extent) if left undisturbed. When I said "equilibrium," I really meant it.

Here is a previous explanation. Please let me know if you want more details:

No, it is not just wind currents. It is the kinetic energy of the motion of the gas molecules. The kinetic energy completely dominates the potential energy of gravity. Molecules bounce around at about 1150 mph. If you took a molecule going that speed, and you directed it upwards in a vacuum (i.e., it didn't hit another molecule), it would go 19 miles upwards before gravity would slow it to zero. These are not objects that are going to "settle out" due to gravity.

It is true that there is a slight enhancement at lower atmospheres; very slight. To cite an example, Ar is about 0.5% of the atmosphere at sea level. At 1000 m (3300 ft), it would be about 0.48%. Clearly, the difference between the top and bottom of your carboy will be negligible.

So, in particular, the gas will NOT blanket at room temperature even if left undisturbed. The temperature IS the disturbance that keeps them mixed.
 
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