Best way to brew delicate or flavoured coffees, and quite pretty to look at.
Positive Product Points
Vacuum brewing is, in my opinion, the best way to brew delicately flavoured coffees, and definitely is the only reasonable way of brewing any kind of flavoured coffee. The Cona size B is appropriate for upto three demi-tasse cups. This is a well made product adhereing to the philosophy of form-follows function. It is simple and robust. People who like to entertain a lot might also derive some pleasure from brewing in fromt of guests, as the process is quite charming. From the practical point of view, this is easy to clean and as it uses a glass filter, really has no parts that need changing, except of course, the burner has to filled when it runs out.
Negative Product Points
The funnel, filter and pot are all made of high quality glass, so one has to be a bit careful. If you heat the pot without any water in it, it will shatter. One has to figure out optimal brewing times. Also the preparation takes a bit of time, say upto ten minutes or so. Some might even find the whole process a bit too fussy for their liking.
This is not a stove top brewer. The heating comes from a spirit burner that is placed under the pot. What this means is that the brew is gentle and is able to extract delicate flavours easily. It is a good idea not to start with cold water. Instead, boil the water beforehand, so that the burner only has to make the miniscus rise.
The brewing process is very simple. Fill the pot with water, preferrably already close to boiling, and place the pot in the arms that hold it above the base. Now insert the the funnel in the mouth, so that it sits snugly atop the pot. The glass stopper/filter should have been insered in the funnel before hand. Now place the grind in the funnel, and set the burner beneath the pot, and light it up. If one started with hot water (I use water that had just been boiling) then within a minute or so the water will rise up through the funnel. When most of the water is in the funnel, make sure that all the grind is well `mixed': give it a quick stir if needed, taking care not to disturb the filter. Let it brew for a while, the time depends on the kind of coffee and how one likes it. When one is satisfied that the brew is strong enough (3-4 minutes for most coffees), remove the burner from below the lamp, exintguishing it by replacing the cap provided. In a few minues the coffee will descend from the funnel. When all the coffee has descended, remove the funnel, and the brew in the pot is ready for consumption.
I should stress that it is worthwhile to really let the descent of the coffee complete. The ground left in the funnel should be dry looking. If it looks moist or slushy then one should wait. These last dregs of moisture are very flavourfull, and can make the difference for some delicate coffees such as those from Yrgacheff.
As has been mentioned earlier, the duration of the brew is variable. Longer for richer coffee, shorter for a lighter brew. To establish the optimal time the following factors should be taken into consideration:
The longer the brew, ie the greater the absorption of flavour, caffeine and acidity. Also other unpleasant components presnt in the grind are present in greater quantities. For delicate coffees, one really has to wait, but for strong robust ones, only minimal time is needed, around 3 minutes or so.
In general finer grinds give better flavour. The problem is that a very find grind might not be stopped adequately by the filter, and might descend in the pot below. I can confirm that I have used espresso grinds without any problems. So best to use quite a fine grind.
As always, the freshness of the coffee. This means roasted within the last 24 hours, and ground just before brewing. The staler the coffee, the longer the brewing time, and as stated in tiret 1, the greater the amount of undesirables in the brew.
To catch the flowey notes present in some coffees, one really has to experiment. I have found that Yrgacheff requires a bit of time (5 min), but that might well have been because the roast was a few days old. On the other hand, a fresh Hawaiian Kona yields itself fairly quickly. Thus, some experimentation is required. Would be useful to have a table that lists type of coffee, age of roast, and time of brewing and the notes/flavours present in the brew...
Very, very rarely it will happen that on removal of the burner the brew does not descend as the pressure is not relieved. A little bit of tinkering with the funnel can fix this. I have seen this happen only twice since I bought mine in summer 2001, so I don't have a reliable remedy or explanation. However, periodically, say once a month, give it a nice clean and dry it up properly. That should alleviate any effects due to a recalcitrant miniscus becoming a bit too fond of a coffee-stained glass surface, which is the only explanation I can think of.
Also, if you brew for too long the slurry in the funnel will start splashing about. Then it is definately time to remove the burner. At that point, it is unlikely that the brew is getting any benefit with being in contact with the grind.
Keep hot water handy, in case you find after the water has ascended into the funnel that there wasn't enough to cover the grind. Simply add sufficient boiling water to make up the difference straight into the funnel, and proceed as you would have otherwise.
Never heat an empty pot. It will shatter---exactly like the heat resistant test-tubes one used in high school.
The alcohol in the burner needs to be replenished periodically, as one might expect. Typically, it lasts for quite a few brewings, so this isn't such a bother. Best to use denatured alcohol, which one can obtain from a hardware shop. It is quite cheap, I paid about $11 for a gallon or so in 2002, and it lasted me years.
Comparison: espresso is richer, this is more aromatic.
I bought this from Sweetmarias.com via post. It arrived promptly on time. A year or so down the line, when I had been foolish enough break the pot by heating it whenempty, Sweetmarias was able to provide me a replacement. Although at that time one couldn't order a size B via their web-site. So they sent the larger pot, and I drove to Berkeley to exchange it.