Tag: vacuum pot coffee brewing

Vacuum coffee pots are probably the most visually appealing way of brewing fresh coffee, as the process is clearly visible at each stage and there’s a lot of movement involved. What actually happens when you put that pot on the heat source, though?

The vacuum pot consists of two glass globes, sitting one on top of the other. When assembled, the lower chamber, which contains the water for brewing, is more or less airtight. As the chamber shouldn’t be filled to the brim, the space above the water will contain a mixture of water and air vapour.

When you introduce the heat source, the pressure exerted on the walls of the container and the surface of the water increases with the temperature. When the pressure exceeds the external air pressure, the water is forced up the funnel into the upper chamber which contains the coffee.

Eventually most of the water in the lower chamber is forced through. Once the liquid level drops below the end of the funnel , the system is no longer closed and the pressurised gas in the lower chamber starts to escape through the funnel and ‘gurgle’ through the coffee, which is when the brewing process occurs.

When the coffee has ‘gurgled’ for a minute or so, depending on how strong you like it, removing the pot from the heat will stop the process. The gases in the lower chamber will start to cool, the volume of air will decrease and the internal pressure reduce, forcing the liquid in the upper chamber back down as brewed coffee.

As the pressure between the upper and lower chambers won’t be completely equal, when you remove the upper globe before serving the coffee you’ll need to use a little effort to break the seal.

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Vacuum pots are a brewing method used by coffee connoisseurs to produce a fresh-tasting, sediment free cup of coffee. If you’re new to vacuum pot brewing, here’s our guide to how to brew the perfect cup. As all vacuum pots are slightly different, remember to read your manufacturer’s instructions first.

1. Take the coffee mug you want to use, and use it measure water into the lower globe of the vacuum pot.Count how many mugfuls you need to fill it to at least half full.

2. When the globe is half full of water, put it on the heat source over a high heat, which could be the hob or a gas burner (this will vary by individual model).

3. Put the filter in the upper globe – you may need to lock it into place, depending on the model you have. Your filter could be paper or cloth, and could use clips or springs to fasten so check with your instructions.

4. Measure your favourite ground coffee into the upper globe, allowing two level tablespoons per mug of water used.

5. As the water in the lower globe begins to simmer, put the upper globe on top and give it a good press down to seal it.

6. As the water in the lower globe begins to heat, the pressure of the vapour will force it into the upper globe. Keep an eye on things, and when half of the water is in the upper globe turn the heat down a little.

7. As the water level in the lower globe touches the bottom of the funnel, vapour will rise up the tube making the coffee bubble and gurgle. The length of time you leave this to happen will dictate the strength of the brewed coffee, so leave it from one to three minutes depending on your taste.

8. Take the pot off the heat. As it cools, a vacuum forms and pulls the brewed coffee back down into the decanter. When this process has finished, carefully pull away the upper globe and serve the coffee.

For a full range of coffee beans at great wholesale prices, suitable for use with all brewing methods, please visit our coffee beans page.