how disastrous is this?

Ok so I started brewing a batch last night... Got it put in the carboy, added the yeast and put the airlock on. About 3 o'clock in the morning, I heard a loud bang. I just assumed the cat had had knocked something over. This morning I get up to find the airlock had blown off the carboy... I washed it off and put it back on. The carboy is being kept in an enclosed cabinet and wasn't exposed to the air for more than an hour or so after the airlock blew off... I'm just wondering how disastrous this is?

You would be suprised how often this happens. Happened to me once, beer turned out fine. Now I use blow off tubes. No more issues.

Cheers

probably not a disaster. if the fermentation is strong enough to blow the airlock off, it probably has a good amount of co2 coming out of the hole to repel any outside air from getting in, so bacteria should be unable to get in.

Oh good...I'm glad... Its my second batch and its an American Bock. I'm really looking forward to tasting it

For it to blow off like that so quickly, you may want to keep an eye on your pitching temperature and your fermentation temperature. If you pitched the yeast when the wort temp was high (above 75-80), and/or your bucket/carboy is sitting in 70+ temps, it could cause a very quick, vigorous fermentation. While that can be very exciting, it can create a lot of off flavors in your final product. Always try to pitch your yeast at or just below your fermentation temperatures. And when beer ferments, it creates heat, typically between 5-10 degrees. So if the room is 70, your wort temp can get up to 80 at the height of fermentation.

Just some thoughts.

I'll echo exactly what JohnnyO said. Most styles benefit from fermentation in the 60 - 70 degree F range. When you exceed that range you increase the yeast activity and it does lead to excessive off-flavors in your final product. Probably something to consider for your next brew. In the meantime, search the site for blow-off tube and you can easily rig something up. I use a blow off tube for every batch since I usually pitch large starters and have a lot of activity.

I'm gonna have to buy a thermometer. I've been guessing and it seems that just isn't good enough.thanks for the input guys

if your really doing a Bock and using lager yeast, and don't have your beer in a fridge, or some other way chilled, your temps are way too high.

I'm a total newb myself and have yet to brew my first batch (it's a week or two away)... but since others are suggesting the temps are too high, AND you've said you've got it in an enclosed cabinet - the latter part may have something to do with it. If you've got 5 gallons heating up due to fermentation in an enclosed cabinet then that will probably allow it to heat up even more. If a more experienced brewer concurs then you may want to get it out of that cabinet for the sake of your airlocks and the final taste of your brew.