To Cover or Not to Cover

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Sep 14, 2009
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I've read about it both ways. During primary fermentation, should you use an air lock and keep out the oxygen, or use cheese cloth to allow the yeast to be exposed to oxygen? I've tried it both ways and haven't seen a lot of difference int he results; however, fermentation seems to slow down with the airlock.
Answer to the title question - cover your primary it will keep stuff out.

What you are really asking is what to cover it with. I use a loose fitting lid. No air lock. I also use a large primary. It's about 11 US gallons for a 6 US gallon batch.

BTW, vigourous stirring before pitching the yeast should incorporate sufficient O2 into the must for the yeast. I really don't think that O2 competing with CO2 escaping from the wine on the surface of the must/wine is all that helpful.

In this forum I've read that many people cover their must with simple cheese cloth to keep out the bugs. Others say they fasten the lid on tight and put in an air lock. It makes sense what you say about the C02. There is so much of that coming out that no O2 can get in. I guess as long as you let the C02 escape, all will come out fine.
I think what Steve meant was don't "open" ferment. Either lay a cheese cloth on top or just lay the lid on top. (keeps the dog from drinking it:) ). In the primary the must need oxygen to reproduce better. Once gravity is around 1.015 rack and put it under a airlock.

It depends on your definition of "open" ferment. To some, a "closed" ferment is a tightly sealed primary with an air-lock. In that case, a loose fitting lid is an "open" ferment, or maybe "semi-open".

BTW, I have had kits re-start a vigourous ferment when moved to a carboy above 1.005. This means wine coming through the air-lock making a mess. [Not wife-friendly, so to speak.] As a result, I wait till the sg is below 1.005, and usually below 1.000.

Open fermenting enables quicker fermentation. The more readily available the oxygen molecules, the faster the reaction. K.I.S.S., right? Unless you have all the time in the world...
I just meant "open" = nothing over the wine. Like you said its all in the verbage.
always cover it with something...once fruit flies/gnats get in there, u r a gonner, man..say hi to vinegar

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