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Open Air Primary (sealed with a towel)

Hello All,
I’m new to brewing but an experienced winemaker. I’ve read a lot the past few days about leaving in primary vs racking to secondary with regards to beer and I understand the different perspectives. My question though is more about the primary itself. I brew all my wine in an open secondary, covered with a towel and sealed with rubber band. I brewed my first beer the same way because I’ve got large fermenters, and wanted to eliminate the need for a blow off hose and bucket (space restraints). The guy at the LHBS said that should be fine and then rack to secondary. However, I’m curious about oxygen exposure after ferment begins to subside, which it is now doing on day 4. Haven’t checked gravity yet today but based on my experience supervising 50+ ferments (albeit wine) I’m pretty sure this is winding down, which makes sense given the original gravity (1.050) it couldn’t take that long.

Being a winemaker, oxidation is always a primary concern, however the ferment lasts long enough and produces so much CO2 the wine is saturated, and can be left open air (covered by towel of course) for weeks if necessary for some techniques with no risk of oxidation. I’m not convinced that’s the case with beer, not this batch anyway. I was told at the LBHS how beer yeast go crazy and the foam can get out of control (why I used the larger fermenter without blow off hose). I found my first brew to be disappointing in that respect- very mild. Which leads me to believe there will be less protective CO2 in the brew than in wine, risking oxidation. So should I rack into a secondary (at least a bucket with an airlock) before ferment completely subsides and I lose the CO2 blanket?. I’m not able to seal it in current primary.

Oatmeal Stout
OG 1.050
Target FG 1.013
Not a kit but got the ingredients from the LHBS.
Boiled and pitched yeast Wednesday (Nottingham)

As a side note, I’m finding brewing just as fascinating as winemaking. Both are the same, but very different at the same time. Lots to learn, and I appreciate any insight. Thanks!

This is interesting. I’ve been wanting to try the open fermentation that I saw on one of the brewing tv episodes so this answer will help me clear up any questions I might get too.

Welcome to brewing it’s fun.

good question, I’m leaving this one for the pros

I’m a newbie, but from what I’ve researched/been told, you should be ok as long as you rack it to a secondary to clarify it or straight to bottles as soon as you hit your FG. CO2 is heavier than air/oxygen and forms a protective layer on top. I’m guessing this will degrade eventually but should be fine 7-10 days.

I was getting ready to do an agressive fermentation in a 1 gal. fermentor and was told to use a 2 gal. or risk losing/blowing the airlock. I didn’t have a 2 gal. bucket and asked if using a 6 gal. would be ok; was told it would be fine.

Not sure if using a towel instead of a stopper/cap to cover it would affect anything though.

As far as oxidation, unless the headspace is physically disturbed as fermentation slows, I think you’re fine.

I often use a standard lid with a piece of sanitized foil placed over the airlock hole for some portion of my ferment, and I feel perfectly comfortable doing so.

The idea of using a towel would make me more nervous than the oxidation risk of a non-closed ferment.

I wouldn’t put any cover on my fermentor that isn’t sanitized, whether it’s a lid, foil, or whatever–how is the towel sanitized? I’m sure it’s a small amount, but I think it’s a near certainty that you get some lint or dander in the fermentor. You’ll probably get away with it, but I think there are other alternatives that less risky. Just my opinion, though :slight_smile: .

I sanitize it with a solution of K meta before placing on the fermenter. Next time I will probably just use my bucket with an airlock and deal with the blow off assembly. The guy at the LHBS just made it sound like a foam version of Hiroshima would occur, but it was more like Black Cat on the 4th of July… Very little foam. Based on his description I thought there wouldn’t be room for it all in my 7.6 gal bucket. Just like everything else, you learn through experience. Thanks guys.

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