dsc01738Word to the wise: if you’re fermenting an imperial stout with a 1.150 starting gravity, make sure your primary has enough head space. Otherwise, you’re likely to get the CSI-type murder scene that awaited me when I came home from work today.

It was unbelievable. I brewed this beer on Sunday, and the build-up of CO2 pressure in less than 24 hours of pitching the yeast literally blew the entire top off of the 6.5 gallon plastic bucket I used for primary. Forget about the air lock…I found the actual lid laying six feet away from its original location tightly secured atop the bucket. Massive chunks of dark krausen sprayed over a 15 foot radius of my dining room, with huge arcs of wort splattered all over the walls and nearby closet door. In fact, fresh krausen was still violently spewing over the edges of the bucket rim as the stout underneath happily fermented away. It looked like a mushroom cloud from an atomic bomb perched atop the vessel.

Frankly, I was a little pissed about the massive clean-up job that lay ahead. But the experimental homebrewer in me was also very excited at what a great job I’d done getting the gravity up and yeast population so healthy by using a starter. 

dsc017401Instead of freaking out and dumping the stout for fear of bacterial infection, I looked at this homebrew-gone-wrong as a fun little experiment. Breweries like Sierra Nevada, Anchor, and many English and Belgian brewers use open fermentation tanks to make their beer…why couldn’t I? Granted, some of these brewers use special air filtration systems in their fermentation chambers to minimize the bacteria problem. But in many ways open fermentation could be considered a more traditional way of crafting an ale or lager, if you think about the way beer was made over the past several hundred years in monasteries or small breweries in 19th century Bavarian villages. My stout of course isn’t a lambic, and I clearly am not interested in wild yeast spores or other nasty air-borne creatures getting in there. But I thought I’d at least roll the dice, let it ferment out and see where we ended up.    

I dragged the bucket down into a corner of my basement, and put it in a larger plastic container to catch the spill-over. The bucket is still frothing as I write this. I’ll give it the standard two weeks and check the gravity again before I rack to secondary, and probably wait a little longer since it’s such a huge beer. Very interested to see how this one turns out.

For those interested, here’s the recipe I used for the 5 gallon batch. Just be sure to get a blow-off tube or huge fermentor before you brew it:

18 lbs. Maris Otter
2 lbs. Roasted barley
1 lb. chocolate malt
8 oz. flaked barley
8 oz. Crystal 60
8 oz. Crystal 120
8 oz. Black patent
8 oz. flaked oats
3 oz. Chinook (in boil at 60 min.)
1.5 lbs. honey (in boil at 15 min.)
8 oz. molasses (in boil at 10 min.)
Wyeast London Ale III (1000 ml yeast starter)

Mashed at 148 for 90 minutes