Vacuum Brewing with the Cona

the finished product

Vacuum brewed coffee. It’s all the rage on the greater coffee loving scene of late. Mark Prince has been into them for years, they’ve made numerous appearances in barista competitions, St Ali in Melbourne invited a Japanese syphon coffee champion to give a demonstration of the art, and snobs and geeks across the country seem to be getting in on the action in greater numbers.

My first dabbling with vacuum brewed coffee happened after I casually dropped by Fiori Coffee to pay Kam a visit and make a nuisance of myself (as I am prone to doing). Noticing a familiar looking device sitting in a box on the floor I soon found out it was a Cona Vacuum Brewer. Kam, being the gentleman he is, kindly offered to let me try it out, and I’ve been experimenting ever since.

The basic principle behind vacuum brewed coffee is that you have two chambers. Water in the bottom chamber is heated, gives off water vapour, and eventually the vapour expands so much that it pushes the rest of the water up the spout into the top chamber. The ground coffee in the top then brews until you take away the heat source, at which point the water vapour cools and the brewed coffee is drawn back down in the bottom chamber.

I am by no means any kind of expert when it comes to this kind of thing. I’ve been picking up as many tips from other people as I can. So this post is more of just a pictorial guide to one way you could do it, rather than any kind of how to.

The Cona is a very beautiful piece of equipment on it’s own. Shannon Bennett fell in love with it so much that he makes a table side bouillabaisse by infusing fish stock and shell fish using it. The process of brewing coffee in it to me seems more like a science experiment than making coffee, but that’s probably why I like it.

My process is as follows:

Filter some water and fill the bottom chamber up. This is a ‘D’ series Cona, which holds at most a litre or so in the bottom. I fill it with about 750 ml of water, and put it onto a gas burner to heat up. This isn’t strictly necessary, but the Cona’s standard heat source is a little spirit burner, which takes forever to heat this amount of water.

Once some vapours are coming out of the top of the pot, and before it starts to boil, take it off the gas, and lock the top chamber in place on top. Light the spirit burner underneath and add the coffee to the top.

I used a measurement of 8 grams of coffee per 150ml of water (I fudged that from the SCAA standard brew ratio recommendations). Which means 40 grams of ground coffee for the amount of water in this example. The coffee is ground at roughly the same level as French press coffee, though I have been varying it lately to see the effects. Obviously you should be using some nice fresh coffee for good results.

Now you basically let the Cona work it’s magic.

The water will gradually rise up into the top chamber and begin to infuse. When it’s all mostly up in the top, I give it a stir to make sure all the coffee is adequately soaked, which brings out the “bloom” some more. Then when all the water has risen to the top (there will always be some water that doesn’t come up) remove the heat source. The coffee will then slowly start to be sucked back down into the bottom chamber, and the spent grounds stay up the top.

Some people wait til the water had all risen to the top chamber before adding the coffee, namely because it infusion all happens at a similar temperature, but I can’t say I’ve tried enough to tell the difference.

Here is my pictoral view of the process:

Cona - Size DCona - pre brewmeasuringground PNG coffeeSpeeding up the processSome assembly requirednearly readyreally nearly readystarting the brewinvisible flameon the boilcoffee slowly infusingInfusingCoffee risingrise my prettyCritical massThe last dropsthe bloomreversethe vacuum working its magicspent coffeeso elegantthe finished product


– This is great way to brew coffee, it’s an interesting process and the results can be amazing

– The Cona has a glass filter rod. I’m not sure how it works exactly, but the cups I’ve had are generally very clean and without grounds. I like that it doesn’t need changing and is easy to clean, but not sure how it compares to cloth filters in brewers like the Hario.

– It works best with interesting single origins that are roasted much lighter than espresso to keep their inherent terroir characteristics.

– Measuring the coffee in the top chamber through the brew process showed I was getting temperatures around 90 – 95C, which is not boiling obviously, so should be ok. A more specific approach to temperature management would give more reproducible results.

– My experiments have yet to yield any outstanding experiences, but I think that’s due to roast level
of the coffee, and mastering the technique some more.

– There are lots of other ways to do it, here’s a list of other resources I’ve been using:

Sweet Marias
Coffee Kid
Coffee Snobs
Coffee Geek

Also, enjoy the giant photos :)

14 thoughts on “Vacuum Brewing with the Cona”

  1. Gorgeous photoset there (as usual) Matt.

    For something different, try playing around with those variables a bit. Try a coarse grind (same a plunger), same stiring action, 45 second steep time with double the coffee (18g per 140mls). Entirely delicious results!!

  2. Cheers for that Ian, so much to try, doubling the amount of coffee sounds like it’d be intense… What sorts of vac pots have you played with ?

  3. Hey Grendel, it takes a bit of getting used to, but I think you’d really love it. Especially with your roasting setup meaning you can roast a few small batches to order and try out the difference of beans at a few different levels.

    The only real problem being how to drink litres of coffee every day without overdosing :)

  4. There’s been heaps of discussion on Coffeesnobs about vacuum/sihpon coffee and it is becoming very popular, I’m heading over to Melbourne next week for a few days, I’ll be checking out the top cafes and BBB’s cupping on the Saturday morning.

  5. I’ve played a little with the cona, but must of my vacpot is done on my Hario TCA2.

    Most of the online chatter points towards a medium/fine grind and similar parameters to what you have been playing around with (and, i should add, makes for a fantastic cup!).

    This figures I suggested represent how i’m now best enjoying syphon, after talking with Luca who attended Meiko’s (Japanese Syphon Champion)syphon workshop @ st ali, and what she was doing.

    I should also point out, that like most things coffee, parameters are blend/SO specific, and will always be changing. Just thought I’d shoot through an alternative.

    There really seems to be a resurgence of alternate brewing styles at the moment, it’s great. I only hope we start to see some dedicated cafe’s helping to puch things forward also.

    Happy Brewing!!

    1. Cheers Trevor, I’ve been checking out some of the chatter on the boards too, it’s great to see so many people getting into it.

      Kam: I’ve yet to give the Vue De Monde bouillabaisse a try, but I think some tea infused salmon would be pretty cool to try in it… if somewhat awkward. Though i’m determined to get the coffee up to standard first.

      Ian: Yeh I see a lot of people using the Hario, it seems like a more practical choice in terms of design if you’re really into the vac pot method. The Cona, whilst great looking, is a little unwieldy to try any of the tricky moves I’ve seen in other syphon coffee demos, but I can still vary a good deal of the parameters I guess.

      It seems like the Clover generated all this interest in brewing as an art form, and then when they suddenly disappeared after Starbucks bought them out, people wanted that alternative method, and started looking into Vac Pots as a way to deliver the clean flavours brewed at stable temperatures. I think it’s great too, the more appreciation there is of the actual coffee the better… I don’t think espresso necessarily delivers the same appreciation of the actual origin qualities as this kind of method does.

      Sounds like you’ll have to have a setup in the new cafe then ? :)

  6. Hmm interesting … I’ve been dabbling with a hario 2 cupper cloth filter thingamajig at home with mixed results. (still trying to fine tune) Would be interesting to compare the glass vs cloth filters. How big are the holes? Does it limit how fine you go so as to not let any muck through? So far the only changes I’ve made was getting rid of the alcohol wick burner that came with and replaced with one of them fancy butane burners. Has made life a little easier but really my whole cloth filter cleaning routine needs some tlc. Cafe Myriad in Montreal has two hario halogen heaters and were running a couple for a pricey $8 a pop. I think the price was based mostly on how time consuming it is to make commercially. Amazin

  7. Jenny McJen: The glass filter gizmo on the Cona is a rod that slides down the middle of the tube. It sits snug in there and has some grooves on the bottom of it that try and allow liquid to pass through, but blocks coffee grinds.

    In practice I’ve noticed you need to be pretty careful, because if you accidentally bump anything while you’re brewing, the rod will jump around and a bunch of grounds will make their way down.

    For the most part though, it’s been pretty clean, though I think you do need to be careful how fine you grind, but my experiments have all been at or around “french press” grind levels and I haven’t got stacks of sediment in my brew.

    I kinda like the idea of the coffee only touching glass the entire time, not sure how a cloth filter would affect the taste… but then lots of people swear by them.

  8. As soon as I saw this I thought of the kingfish dish we had at Vue de Monde where this gets done at the table. Real dining theater I tell you!

    Sigh, it’s times like this I wish I drank coffee…

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