Airlock/Stopper for Long Term Aging

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

jrebella

New Member
Joined
Feb 14, 2022
Messages
4
Reaction score
5
I have a few glass carboys that I use to age sours or other mixed fermentation beers long-term (6-18 months). In the past, I had used a standard airlock with a drilled rubber stopper. Last year, I wasn’t checking on them regularly, and one of the airlocks went dry. By the time that I noticed, the beer had developed a vinegary taste and had to be dumped.

In response, I started replacing the airlock and drilled rubber stopper with a solid rubber stopper after fermentation stopped. This solved the airlock issue, but as temperatures went up, I began to worry that increasing temperatures would force out the stoppers. (The carboys are in a room in the basement. The temperature does not swing wildly, but there are seasonal effects.) Last week, I “burped” each of the carboys by temporarily removing the stoppers, and a decent amount of pressure had built up in each one.

I saw these breathable silicone bungs on MoreBeer: Breathable Bung for Glass Carboys | CellarScience® | MoreBeer

This would seem to solve the immediate problems – there’s no airlock to go dry and it would not allow pressure to build up. But I know that silicone is pretty oxygen permeable, and I’m generally very wary of cold-side oxygen exposure. On the other hand, the beers that I’m keeping in the carboys are traditionally barrel-aged, so might not be negatively affected by the oxygen permeability.

Another, more expensive and space-consuming option, would be to buy additional kegs and in age in keg once fermentation stops.

I can also continue on with the rubber stoppers and either (a) check airlocks more religiously or (b) release pressure from the solid stopper whenever the temperature increases. But I prefer a solution that is failproof.

Any thoughts? How do people generally age these beers for a long period of time?

Thanks
 
Congrats with your first post!
It's well written and you did good research, offering good viewpoints to comment on. We wish getting threads/posts like these much more frequently.

Due to the oxygen permeability of silicone, those "breathable flappers" are definitely out for long term aging.

Some of us use an (O2 impermeable) mylar party balloon as a breathable headspace expansion when cold crashing. You could probably rig something like that up. Use oxygen impermeable EVA Barrier tubing for the connections.
 
You could change to a PET fermenter like the Fermonster. Then simply add a ball lock post to the lid and use it for a blow-off tube. Once active fermentation is completed and you want start aging, you can remove the blow off tube without worries. If you want to burp it later on, just reattach it.

Add a 2nd ball lock post to the lid and a floating dip tube and you can also do closed transfers to your kegs.
 
Congrats with your first post!
Thanks!

You could change to a PET fermenter like the Fermonster. Then simply add a ball lock post to the lid and use it for a blow-off tube.
I think doing this with a Fermonster would be a good idea if I was starting from scratch. (I actually have a Fermonster with the ball lock post lid that I use when I do fruit additions; it's a good setup.) But cost-wise getting a Fermonster with a solid lid and adding the ball lock posts and dip tube is basically in the neighborhood of buying a used keg and then just doing a closed transfer from carboy to purged keg after fermentation. Given that I already have the carboys, I'll probably stick with them.
My initial thought is a blow-off tube into a bucket.
This is definitely what I'll do as the immediate solution. I don't see why EVA barrier tubing into a jug of water would be any worse than an airlock.
Some of us use an (O2 impermeable) mylar party balloon as a breathable headspace expansion when cold crashing.
Thanks for the idea, I've heard of that for cold crashing, but hadn't thought of it for long term aging.
 
FWIW I have some long-term aging in glass carboys as well. I just put on my calendar to top up the bubblers with vodka on a regular basis so they don't run dry. It's the cheapest solution for me, hope you find a system that works for you as well.
 
This is pretty convincing evidence that the silicone bung is not an acceptable solution.

Though it also pretty much says that any of the standard bung/stoppers and an airlock is not an "acceptable solution"...or at least allows for oxygen ingress. I am not positive if the Better Bottle devices that did decent are still manufactured (the DryTrap or PET O-Ring Closure). I did find one listing of the PET O-Ring Closure for $15:
https://www.homebrewohio.com/better-bottle-pet-o-ring-closure/
So I am not sure if 1) oxygen ingress of a standard bung/stopper and an airlock or blowoff tube is actually a problem to worry about and 2) if it is a problem what is the solution?

I only occasionally long term age something like an Imperial Stout in a glass carboy with a stopper and airlock. I am not sure that some oxygen exposure is a terrible thing. These types of beers are exposed to oxygen when barrel aged. I might keep a beer in one of my PET Fermonster fermenters for 3-4 weeks (with the HDPE lid, a "Universal Rubber Stopper", and a vinyl blowoff tube).
 
Though it also pretty much says that any of the standard bung/stoppers and an airlock is not an "acceptable solution"...or at least allows for oxygen ingress.
I mostly meant that the silicone bung lets in a lot more oxygen than an airlock. The Better Bottle measurements showed 14x as much oxygen ingress on a solid silicone bung as on a standard airlock. I would expect that a silicone stopper that was designed to release air would be even more permeable.

I am not sure that some oxygen exposure is a terrible thing. These types of beers are exposed to oxygen when barrel aged.
I absolutely agree, and I'm not chasing zero oxygen exposure on these beers either. I would just be worried that the acceptable level of "some oxygen exposure" is somewhere between using the airlock and 14x as much oxygen as the airlock.
 
I mostly meant that the silicone bung lets in a lot more oxygen than an airlock. The Better Bottle measurements showed 14x as much oxygen ingress on a solid silicone bung as on a standard airlock. I would expect that a silicone stopper that was designed to release air would be even more permeable.

Looking closer at the document, I now notice that the graphs are not consistent in the X and Y axis values. I did not notice that both the Silicone Bung and the "Orange Cap" both had a X axis up to 1.6, where most of the others are 0.16. The graphs made them look closer where the values were actually very different.
  • 114 cc/day: "Orange Cap" with caps in place
  • 19.6 cc/day: Solid Silicone Bung
  • 1.2 cc/day: Plugged Buon Vino Bung (looks similar to what I normally use)
  • 0.0 cc/day: Solid Rubber Stopper
  • 2.6 cc/day: Rubber Stopper w/ S-Airlock
  • 1.4 cc/day: Rubber Stopper w/ 3-Piece Airlock
So I would wonder how using a well fitting rubber bung with a small mylar balloon would measure.
 
Dr. Jeff, I've often considered something like your oil/fermcap suggestion. Always bothered me that nobody ever seemed to consider the diffusion of O2 back through the water of the airlock. But, it has to be something that won't spoil the batch if you screw up and get liquid from your airlock back into the fermenter during a temp drop or something. Somehow, I had never though of just floating a bit of something non-polar that O2 doesn't so readily diffuse though, on top of what you normally fill an airlock with. By floating some food safe oil on top, after you fill the airlock as usual, you'd have to work really hard to get the oil to backwash into the carboy. I like it. I like it a lot.
 
Back
Top