Airlocks- why?

[MarkA]

Do you use an airlock when fermenting beer?

I use a (clean) tea towel to cover the hole in the top of my FV (just the right size for an airlock, ironically) to stop any dust/bugs/whatever else floating in, and it gets put in my brewfridge for 2 weeks. I would never consider using an airlock unless;

a) I'm making wine (where the ferment will take a month or two and it can be a year or two before it's ready to be bottled) or

b) I'm making a beer that needs to condition in the FV for a few months before bottling.

No commercial brewery that I've ever visited use any kind of sealed fermentation, so I'm curious as to how has this become standard with a lot of home brewers?

[Secla]

If in a brew fridge it obviously limits the possibility of contamination, I used to use one but ive recently just been leaving the lid cracked open a bit
No problems as of yet

[IPA]

Foam bungs are best if your FV is suitable.

[Jocky]

If you want to have any kind of bulk conditioning time post ferment then you need to keep air away from the beer to avoid oxidation. If you don't have the option of moving to a vessel where you can purge with CO2 then you need to keep the CO2 in from the primary fermentation, and for that an airlock is pretty essential.

[Clibit]

If you want to have any kind of bulk conditioning time post ferment then you need to keep air away from the beer to avoid oxidation. If you don't have the option of moving to a vessel where you can purge with CO2 then you need to keep the CO2 in from the primary fermentation, and for that an airlock is pretty essential.

Only if you have a hole that needs filling. And I haven't.

[MarkA]

If you want to have any kind of bulk conditioning time post ferment then you need to keep air away from the beer to avoid oxidation. If you don't have the option of moving to a vessel where you can purge with CO2 then you need to keep the CO2 in from the primary fermentation, and for that an airlock is pretty essential.

That's fair enough Jocky, like I said I would use an airlock for that purpose. I just don't really understand why brewers use them for the primary fermentation.

If in a brew fridge it obviously limits the possibility of contamination, I used to use one but ive recently just been leaving the lid cracked open a bit
No problems as of yet

Before getting a brewfridge set up, I was using tubs of water in the garage with aquarium heaters in them to control fermentation and, previous to that, my FV was stood in a bedroom with the lid cracked open. Maybe I've just been very lucky to avoid any contamination?

I love this about the hobby - everyone has their own ideas and processes and none of us are wrong, it's good to hear about different ways of doing things

[MarkA]

Foam bungs are best if your FV is suitable.

I haven't seen these, I'll have a search as this would be a better method than using a tea towel! Cheers

[sonicated]

That's fair enough Jocky, like I said I would use an airlock for that purpose. I just don't really understand why brewers use them for the primary fermentation.

Some people just like to see it bubbling away - me included. That said I can't be arsed any more so just leave the lid cracked off on one side.

I don't understand why they're essential for bulk conditioning though. If I can't keg when fermentation has stopped I'll just seal the lid up and leave it for a few weeks until I can keg. Surely there's no oxygen in there as the CO2 has pushed it all out?

[chefgage]

For me personsonally i have used both the airlock and the lid just cracked open method. When i first started i would just crack the lid open a bit and never had any infection problems. But i have moved onto using an airlock for two reasons, one, i like the idea of the closed vessel and two, its always nice to see the airlock bubbling away!!

[Jocky]

I have done, and still do that on occasion. But I also make sure that the moment primary is done or is close to being done I'll button the thing up for any conditioning period.

The problem is that if you put the 'leave it open' bit of advice along with 'secondary is pointless, I just leave it in the primary for 2/3/4 weeks' then you end up with an open fermenter full of beer for several weeks, and massively oxidised beer.

I know because I did it several times before I realised

I didn't oxidise every beer, just the ones with either dry hops or a reasonable amount of crystal, but still.

[simon12]

Why not use one they are as good as a tea towel or foam bung plus you can see how much its fermenting

[Tony1951]

I don't understand why they're essential for bulk conditioning though. If I can't keg when fermentation has stopped I'll just seal the lid up and leave it for a few weeks until I can keg. Surely there's no oxygen in there as the CO2 has pushed it all out?

Yes and CO2 is heavier than air in any case so it will sit like a blanket on top of the beer as long as the lid is on and the gases are undisturbed.

It's like the way beer is stored in the cheap plastic barrels. People keg up their beer with some sugar in for a secondary fermentation and there is two or three inches of air on top of the beer from when they shut the lid. As the priming sugar ferments out the air is raised off the beer by the heavy co2. It will keep like that for months. I just refreshed a flat keg I gave to a lad for his birthday. I made it last July, it was flat by November and three weeks ago I found it in his garage, half a barrel and when I opened the tap and it sucked in air like a drowning man. I opened it poured in 50g of table sugar and shook it up. Two weeks later it is pressured up and completely fresh tasting. It is a stout mind so not the subtlest of tastes but it is absolutely drinkable and it has been abandoned and flat for at least six months.

[gobuchul]

Never used an airlock and never had an infection.

I don't even crack the lid, the lid will leak once the pressure begins to build.

[BrannigansLove]

I've always used one because that's what I was told to do when I started brewing kits. I'm going to try without one in my next brew, as I'll be doing a saison using WLP565, and this is meant to be pressure sensitive.

[Jocky]

I don't understand why they're essential for bulk conditioning though. If I can't keg when fermentation has stopped I'll just seal the lid up and leave it for a few weeks until I can keg. Surely there's no oxygen in there as the CO2 has pushed it all out?

Yes and CO2 is heavier than air in any case so it will sit like a blanket on top of the beer as long as the lid is on and the gases are undisturbed.

The 'CO2 blanket' is a dangerous simplification. Once mixed, gases don't unmix under a normal gravitational force, it's too weak a force to overcome entropy that causes gases to mix.

It would be better to think that you have a higher concentration of CO2 (and/or a lower concentration of O2) in the headspace that helps slow the staling/oxidative reactions.

Your pressure barrel works well because the carbonation process in the keg is fermentation that reduces the O2 and increases the CO2 in the headspace.