Vacuum brewing makes the BEST coffee. Press pots don't hold a candle to vacuum pots, and the've been around for about 150 years! So you have to wonder, why haven't you ever heard of them?
The vacuum method of brewing coffee was invented in the mid nineteenth century. People wanted to brew finer ground coffee without the grounds getting into the finished product. Thus was spawned the vacuum brewer, or simply vacuum pot.
Vacuum pots saw their heyday in the thirties, forties, and fifties. But mysteriously died out at the begining of the sixties, no American companies were making them anymore. The reason for this is often attributed to convenience and speed. Cleaning a vacuum pot is a little more involved than simply throwing out the filter in an auto drip coffee maker. Also, depending on the model, a vacuum pot can take up to twenty minutes to brew a few cups of coffee. The postwar push for automation and convenience over quality is thought to be the primary contributor to the death of the vacuum pot and the rise of drip coffee.
What It Is
The vacuum pot usually consists of three parts; carafe, filter, and the syphon tube/upper chamber.
There are many styles, including the more majestic balance brewers, but for the most part they all adhere to the basic components. For this write-up I will simply describe mine, a narrow neck Silex.
The carafe is glass with a bakelite handle, and has a very narrow round neck; about one inch diameter.
The Upper chamber is shaped something like a funnel crossed with a fishbowl. It is about the same size as the carafe and is also glass. There is a small gasket around the outside of the syphon tube, this is were it joins to the carafe.
There are many different styles of filters; cloth, ceramic, metal, paper, and even all glass; as pioneered by the Cory models. All glass filters are rod shaped, with a bulge in the middle. The bulge has a surface like sandpaper, allowing water to pass under it, while catching the grounds. Silex later improved on the glass filter, adding a metal hook on a spring to the bottom of the rod, to connect to the bottom of the tube to prevent the rod from being dislodged during brewing.
A picture's worth a thousand words. If you still can't visualize this wonderful device, try searching eBay for "vacuum coffee".
How It Works
The carafe is partly filled with near boiling water, if you use cold water, it will take forever to heat up on it's own. Attach the filter to the upper chamber, and then insert the upper chamber into the carafe. Dump the desired amount of grounds into the upper chamber, depending on how strong you like your coffee. Oh, and you're using freshly ground coffee, right? Because if you're using stale coffee, you might as well just use a perk.
Some of the fancy pots these days, such as those made by Cona, include spirit lamps. This way you can brew right in the middle of your table, in front of your guests, this is a good thing, vacuum brewing looks pretty cool. Many of the older models had plug-in hot plates fitted to the size of the pot. But not all pots have their own heat source, so like me, you might have to use the kitchen stove. Put the assembled and filled vacuum pot on a medium heat and watch the magic happen.
As the water heats up, water vapor is released, and begins to expand. But since there is no escape above water level, the vapor pushes the water down, and up through the tube attached to the upper portion. Water slowly flows into the upper chamber, mixing with the grounds, releasing that pleasant coffee aroma. This goes on until the water level in the carafe drops to the bottom of the tube, when suddenly the vapor escapes causing violent bubbling, this is why vacuum pots are often mistaken for boiling the water. Depending on the design of your pot, this bubbling may be sufficient to mix the grounds and water (See the Hario Nouveau for a good example). But in most pots, you may need to stir the brew a bit yourself.
How much you stir, and how long you leave the pot on the heat at this point is really up to you. The more contact the water has with the grounds, the more flavors will be extracted. Just keep in mind that different flavors are extracted at different times, and the vast majority of the bitterness in coffee is caused by over extraction. I find that two minutes of brewing is just right for me.
This is where the vacuum comes into play. Once the grounds have soaked for the desired amount of time, remove the pot from heat. The remaining water vapor will quickly contract as it cools, sucking the coffee from the top back down to the bottom. The suction is powerful enough to dry out the spent grounds.
And there you go! Simply pull the top off the carafe, pour, and enjoy the best damn coffee you've ever had. Just try not to think of the cleaning task ahead of you.
Obtaining a vacuum pot
Several companies including Cona, Hario, Bodum, and Yama make vacuum pots today. You can find these at the rare coffeehouse or department store, although websites such as SweetMarias.com will probably be cheaper. The only siphon pots I'm aware of are handmade, and available only on eBay. Just as functional are the antiques. You may be able to obtain, through eBay or your local antique store, a perfectly good vacuum pot made by Silex or Cory.
One of the advantages of vacuum pots is the fact that most models are almost completely free of paper, plastic, or metal. For example, in the Cona and Cory pots at no point in the brewing process does the coffee come into contact with any material other than glass. Other materials can alter the flavor of the coffee, something you might want to take this into consideration in your purchase. But then again, chances are you'll never notice unless you're one of the obsessed alt.coffee cognoscente.