Foil + rubber band instead of airlock in a pinch ?

Chalk it up to me being hungover, but I cannot for the life of me find my last bung + airlock. I've searched pretty much everywhere and I think I might have thrown them in the bin by mistake while gettign rid of old plastic bags and junk in the brew room.

Now I have my Winter Warmer mashing (hit temp dead on, though...) but nothing to provide an airlock on my carboy. Can I just cover the mouth of the carboy with aluminium foil and tie a rubber band so it stays in place ? The other option is simply stripping my bucket fermenting Witbier of its airlock, changing the lid for an undrilled one and just going for a loose lid fermentation...

LHBS is closed today and on Monday, I'm going away Thursday and will be gone until Friday, wich means any of the options will have to work for a longish time.

in a pinch, sanitize a balloon and stretch over the mouth of the carboy until you can get an airlock. will take a good sized balloon but walmart is open 365

There is at least one major brewery doing fermentations
in giant open square fermenters. How do they get away with it?
Because they are pitching a huge amount of yeast that
starts fermenting before other bugs can get going.

Here's how they did it in Germany around 1930:
http://www.retroyoutube.com/2007/12/retro-youtube-1930-german-beer-factory.html

I would say a loose lid would work fine, or a tight lid with an aluminum
foil tube closed at one end with pinpricks, taped to the lid.

Ray

sanitized foil will work just fine.

Bacteria and wild yeast cant crawl, they can only drop in from above. The loose foil covering will prevent any infection as long as the foil and lip of the carboy are sanitized properly. Since fermentation will be active, the co2 forming in the carboy will push out any air just like with an airlock.

You can make an airlock pretty easily with some tubing and a container of starsan.

Foil and rubber band is pretty much all I ever use.

Will just go with loose lid. The technique has worked fine for me so far and I don't feel like messing with a big, heavy glass carboy.

Got a bitter going right now with just foil, no rubber band. Fermented quite a few this way, even though I have plenty of airlocks.

The only downside to this is fruit flies, gnats or other creepers. Since the temperature has dropped around here, I haven't had any fruit fly problems.

Some even swear that this method is better for your yeast due to less pressure.

I couldn't find the lid for one of my big pail fermenters once. I just covered the whole thing with sanitized foil. Came out just fine.

Although I use blowoff tubes for my fermenters, I just use foil (no rubber band) for my starters. No problems yet.

FWIW, I secondaried a stout in a glass carboy for 6 months with just several layers of foil crumpled down over the top, not even a rubber band. No bugs, good stout. I probably "got away" with it, not a good practice, but it can be done!