Primary Cover Airlock Vs Cloth Alcohol Loss

[Scooter68]

OK I've been reading the pros and cons of using an Airlock during Primary Fermentation and of course I may very well be overthinking this but..

Since the bulk of the alcohol in the wine is produced during the primary fermentation phase - What prevents evaporation of the alcohol in a cloth covered fermenter?

What got me really thinking about this was a glass of wine left on a counter for a day and a half - checked it and as I expected there was almost no detectable alcohol content remaining. Does the presence or SO2 and CO2 production inhibit any evaporation of the alcohol.

Certainly not a chemist or physics major here but just wondering.
I've done both on my wines so far but mostly covered with airlock -though I have noticed that my 5 gallon fermenters (making 3 gal batches) often so virtually no bubbling through the airlock - Unless I wet the seal before latching it down on the bucket. I also figured that the 2 gallons of airspace should permit better release of the CO2 and any excess SO2.

Again still learning about the processes but so far other than one bad batch of Strawberry last fall, all have come through very well. Have my 11th batch working since July 2015. The last one for a while is a 3 gallon strawberry in primary as I write. Bubbling away at about one 'burp' per second through the airlock. This batch is using 14lbs of frozen strawberrys with K1-V1116 yeast. Starting SG was 1.112. Temp in the fermentation room is running at about 65 degrees.

I know that this has been hashed and re-hashed but I just haven't heard anyone address potential loss of alcohol content in an cloth covered fermenter.

 

[AZMDTed]

That's an interesting question, and perhaps someone can answer with some science. I'll just go with anecdotes. My primary bucket is one that doesn't allow the lid to snap shut, instead by design it just sits on top, though it does have an airlock hole that I use which I wonder about. Without a seal there is plenty of room for air to enter and gas to escape, but not much room for dust, bugs, and other foreign objects to enter the wine. One thing to keep in mind is that yeast need oxygen, and during the early stages of wine making oxygen is critical. It's only later that oxygen becomes a risk.

My thinking is that if there was any significant risk of alcohol loss based on how sealed the primary was I think there would be a great deal of literature on it. So for me, the absence of that literature and a great volume of literature regarding putting the lid on loosely, covering with a towel, etc is enough to convince me that at this stage access to oxygen outweighs whatever risk there is of gas (CO2, alcohol evaporation, etc) escape.

 

[cmason1957]

I always look to commercial wineries, many (maybe most) of them ferment reds in open air containers, sitting outside.

 

[Scooter68]

That's an interesting question, and perhaps someone can answer with some science. I'll just go with anecdotes. My primary bucket is one that doesn't allow the lid to snap shut, instead by design it just sits on top, though it does have an airlock hole that I use which I wonder about. Without a seal there is plenty of room for air to enter and gas to escape, but not much room for dust, bugs, and other foreign objects to enter the wine. One thing to keep in mind is that yeast need oxygen, and during the early stages of wine making oxygen is critical. It's only later that oxygen becomes a risk.

My thinking is that if there was any significant risk of alcohol loss based on how sealed the primary was I think there would be a great deal of literature on it. So for me, the absence of that literature and a great volume of literature regarding putting the lid on loosely, covering with a towel, etc is enough to convince me that at this stage access to oxygen outweighs whatever risk there is of gas (CO2, alcohol evaporation, etc) escape.

Good point about the need for oxygen - I should probably read more on that. But that then begs the question - several others threads touching on this topic state that the CO2 and SO2 being released act to prevent oxygen from causing oxidation.
Interesting - the more I learn the more I realize how much more there is to learn. I imagine that the evaporated Alcohol amount might not be all that significant unless you use a primary container with too much surface area for the volume of must. I figured that my 5 gallon bucket that now has about 3.5 gallons of must is about right. (It's food grade container I purchased with the lid at Lowe's - that's why it's a 5 and not a 6 or 6.5 gallon container)
Happy to hear more on this or if anyone has a reference to a study or document that looks at this from something more than "We've always done it this way." Not to doubt folks but since there are at least 2 views on this I would be interested if anyone researched and found perhaps that it doesn't matter??

 

[AZMDTed]

Happy to hear more on this or if anyone has a reference to a study or document that looks at this from something more than "We've always done it this way." Not to doubt folks but since there are at least 2 views on this I would be interested if anyone researched and found perhaps that it doesn't matter??

As someone who's lived through Total Quality Management, Business Process Re-engineering, Lean, Six Sigma and other process improvement strategies I'm a firm believer in "There's usually a reason why we've always done it this way"

That's not to discount the possibility that there really are better ways to do things sometimes, that's where innovations are made and I like innovations, but I always try to understand why we're doing things the way we are before I change them. I think that's where you're coming from too so we're in agreement.

And the business manager side of me always looks at the new buzzword and wonders: What does it do for me that common sense won't?

 

[Scooter68]

ooooH! I remember those programs. I was fortunate to only suffer minor 'injuries' with the TQM - And I agree, always open to new ways but it's a shame that sometimes we fail historically to pass on WHY we do things a certain way which, as you mentioned, lets the Hotshot up and comer pursuade the bosses that he knows how to make things 'better.' Yeah, lotta pain and wasted energy and resources suffering through those experiences. Makes me even happier to be retired and away from those things.

Of course both of these methods work and I was just wondering about the science behind them both. Is one perhaps slightly better for certain types of wine/fruit or yeasts etc. If you are shooting for a higher ABV in the end I suppose that an airlock would help insure that but would that, as some suggest, open you up to potential SO2 issues.

I've lost one batch of strawberry before and unfortunately I don't remember if I cloth covered that batch or airlocked it. That's one reason behind my question. That batch developed the Sulfur smell and all efforts to recover failed. Ended up with a very low alcohol pale product that has little flavor and still has a slight 'essense of sulfur' smell. About ready to dump it unless someone has an alternative potential use for it like turning it into a strawberry vinegar -not even sure that would be of any uses especially with that SO2 odor hanging around.

 

[joeswine]

in the mix

Your talking about a product in the works and then a finished product to different reasoning. Your over thinking the process, it's not rocket science.