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Imagine that brew-day rolls around and you find yourself without an airlock for your carboy or bucket.

What other things can you use in it's stead?

Further imagine that you do not have the materials for a blow-off tube. Touch on infection risk and what to do if you also do not have a stopper.

Inspiration for this question goes to WhatsBillDoing.

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Taking credit for inspiring this. Booyah. I ended up using the one airlock I had, and I'll deal with it if I decide to brew again this weekend before getting my LHBS – WhatsBillDoing Feb 5 '10 at 20:58
up vote 9 down vote accepted

A sanitary piece of aluminum foil crimped over the top or even a plastic baggy with a rubber band on the outside (either use a new roll/box or pour some of your favorite high proof liquor on it just to be sure) should do the trick.

  • Bacteria and wild yeast in the air typically move with air currents (cough/sneeze/fan/air vent...), but without any air current they will generally drift downward (its raining bacteria!). That being said, some crimped foil or baggy over the top will prevent any bacteria/wild yeast from falling into the fermentor (they won't drift 'up' as easily) while allowing CO2/fermentation junk to simply come out the bottom.

  • here is a yeast starter as an example: http://www.manskirtbrewing.com/starter.shtml

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bacteria and wild yeast don't crawl... so this would work just fine. – comat0se Feb 5 '10 at 22:22

I have no idea if this would work, but if you were using a carboy couldn't you just stretch a balloon over the top and put a few small holes in it with a pin? I would think the hole would seal up, but open if there is enough pressure from the CO2 and allow the gas to escape without letting oxygen in. Obviously I have never tried this, but your question got me thinking and I think maybe this would work in a pinch.

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I upvoted not because I know this will work, but because I really like the ingenuity. – JackSmith Feb 5 '10 at 18:06
This is a clever trick. – Dean Brundage Feb 5 '10 at 21:13
This is a clever trick. I'd put a rubber band on the mouth so it doesn't fly off. – Dean Brundage Feb 5 '10 at 21:14
Had a grandma that used to make cheap bootleg wine this way. The balloon is old school. No poking of holes necessary, it'll inflate the balloon. – comat0se Feb 5 '10 at 22:22

Find a huge plastic bin with a top that you can put your fermenter in. Sanitize the walls of the bin. Put in the carboy of wort. Pitch a huge starter... and welcome to the world of open fermentation.

EDIT with addition:
I suppose you could just as well put an inverted glass cup over the top of a carboy. That would keep stuff from drifting in from above. I might have to try this sometime.

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Personally, I have a jury-rigged blow-off. I have the typical universal Carboy bung that the airlock goes into, and put in my old racking cane (that was wanting a use once I bought the auto-siphon). Then attach the hose that fits the racking cane, bottling bucket, bottle filler, etc. and coil in a spare 1-gallon bucket with water. Might not be as good as a real blow-off hose, but it has worked on some surprisingly active fermentations.

I've also heard of using the balloon trick mentioned above, only that you drain the air a few (3-4) times per day.

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The question said not to use a blowoff tube. – Homebrew Holli Feb 24 '10 at 15:16

This is a fun game.

How about a condom with a small hole poked in it? Lubricant free, of course.

There is definitely a slight chance of contamination, but a pin prick of a hole is better than open fermentation. And the condom should be a tight enough fit to make a seal around the neck of the carboy. Might need to buy Magnums though...

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...only if you don't already have them on hand. – JackSmith Feb 5 '10 at 18:06

Ginger beer fermenting in 6-liter water bottles with simple baggie airlock.

enter image description here

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