Covering both for "cask conditioned" Ales and for "Marin Brewing Company's IPA".
If you frequent beer bars in the US and England regularly you may start running into cask conditioned ales. With thousands of micro-breweries out there, brewmasters are stretching the boundaries of ingredients and temperatures to brew a beer that is unique and distinct.
As many of us know, there are some beers out there that are close to perfect as is. Instead of trying to reinvent the wheel, many brewmasters are going back into history of brewmaking in an attempt to bring back some great tastes that have been forgotten.
You might be thinking, "Hey Mattie, what is a cask conditioned ale?" Good question. I didn't know myself until recently. My favorite SF beer bar, Toronado, serves 4 varieties of cask conditioned ales on tap. They change out the different types once a week and I felt like I was missing out on some good bers. So I decided to inquire about the hand pumped beers and ordered a handful the other night.
Most bars won't carry cask conditioned ales because they spoil very quickly. Hence why someone invented the modern keg and CO2 pump. The tap on a handpump looks very similar to the modern apparatus, except when you pull down on the handle you are actually pumping the beer out of the cask. The bar tenders have to forcefully pull down to draw the beer out and some of them even lean on the tap to pump out large quantities.
The best analogy I have to a cask conditioned ale is to beers that undergo a second fermentation in the bottle. Think of Habo's brew kit. A cask conditioned ale also undergoes a second fermentation but instead of in the bottle its in the barrel. Normally, draft beer is dispensed by forcing CO2 into the keg and pushing it up through the draft lines. This method adds carbonation to the beer. Since casks are not designed for a CO2 line, the beer must be dispensed by a hand pump, which acts just like an old-fashioned water pump. Because the beer is undergoing a second fermentation as it's being poured, it creates its own carbonation.
Hand pumped cask conditioned ales have three distinct features.
First, they are warmer than a normal draft beer. I'm not sure exactly how this occurs. I believe the increased temperature is either due to the friction during the pumping process or the fact that cold CO2 is not being pumped in. Either way the temperature makes hand pumped beer distinct. It's still refreshing and isn't warm enough where you feel like you are sipping on a wounded solider the next morning.
Secondly, hand pumped beer is less carbonated. The second fermentation does not produce as much CO2 as the modern method and is also clearly reflected in the taste. This is highly preferable to a modern keg system and great on your stomach if you want to down 8-12.
Thirdly, and most surprisingly the beer tastes "thinner". This is a hard sensation to explain to others who haven't tried a cask conditioned ale, but the beer almost melts across your tongue in your mouth. When you take a swig, the beer almost splits and rolls off your tongue to both the left and right of your mouth. Its a very smooth feeling. Its as if you are drinking a light beer, but no flavor is lost. This is why so many people believe cask conditioned ales taste fresher.
As for the Marin Brewery Co. IPA, it holds up very well in the cask. I thought it would be fitting to tie a Marin beer to this post, as it was my birthplace. The Marin IPA has the nice hoppiness you want from an India Pale Ale but it is definitely not overwhelming. I think IPAs are good beers to get hand pumped due to the "thinness" effect I was explaining above. It also has a "treey" taste, kinda like a little aftertaste of a forest. If I knew more about trees I could be more specific. But when you sip it, I think you'll understand.
Anyway, be on the lookout for cask conditioned. They be tasty.