How to Brew with a Siphon
Two glass globes, a burner and a cloth filter. Vapour pressure pushes water upward into the coffee, then the vacuum of cooling glass sucks it back down. It is the most theatrical brewer there is and the cup genuinely justifies it.
At a glance
- Coffee : water
- 1:15
- Active time
- 5 min
- Total time
- 10 min
- Makes
- 2 cups
- Serve
- Hot
- Kit
- Siphon brewer
Ingredients
Note: Most siphons ship with a cloth filter. Keep it wet in the fridge in a jar of water between uses: dried cloth goes rancid and taints every brew after.
Method
-
Fit the filter
Rinse the cloth filter in hot water, drop it into the upper globe, pass the chain and hook down the stem and clip it on the bottom rim.
Tug the chain so the filter sits flat and centred. A filter sitting at an angle lets grounds past.
-
Hot water into the lower globe
Pour the 360 g of hot water into the bottom bulb and set it over the burner. Starting from cold works but adds five minutes of waiting.
-
Seat the upper globe and let it rise
Push the top globe in until the seal grips. As the water boils, vapour pressure drives it up the stem.
A little water always stays in the bottom. That is correct and it is what keeps the vacuum from breaking early.
-
Add coffee and stir once
When the water has risen, tip the coffee in. Stir gently in a few back-and-forth strokes to wet all of it, rather than swirling.
The grounds will otherwise float in a raft on top and never extract.
-
Steep ninety seconds, stir again
Leave it brewing for 1:30, then give it one more gentle stir just before you take the heat away. This second stir settles the grounds and speeds the draw-down.
Steep 1:30 -
Kill the heat and watch it fall
Remove the burner. The lower globe cools, the pressure drops, and the vacuum pulls the coffee down through the filter in thirty to sixty seconds.
The spent grounds should settle into a flat dome. A dome with a crater means the stir was uneven.
Draw-down under 1 minute
Why this works
The physics is straightforward and it is the reason the brewer works so well. Heating the sealed lower globe turns some water to vapour, which expands and forces the remaining liquid up the stem. Up top, the water sits at a steady temperature just below boiling, because it is being held there by the vapour beneath it rather than sitting on a flame.
That constant temperature is the siphon's real advantage. In a pour over the water cools as it works down the bed, so the last of the extraction happens cooler than the first. A siphon holds temperature for the whole steep, which gives an unusually even extraction.
Then you remove the heat and the vapour condenses. The pressure in the lower globe drops below atmospheric, and the difference pulls the brewed coffee down through the filter. That is a gentler, more complete draw than gravity manages, which is why there is almost no coffee left behind.
The cloth is the last piece. It takes out the grounds but passes more oil than paper, so the cup is clean and bright like a pour over but with more body. A paper or metal filter kit changes that balance in the expected directions.
Variations
- Lighter: 1:16 and shorten the steep to a minute.
- Paper filter kit: cleaner and more delicate, closer to a Chemex.
- Butane burner: more controllable than the alcohol lamp most siphons ship with, and worth the swap.
Made it?
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Questions
Why does the draw-down take forever?
Too fine a grind, or a clogged cloth filter. Go coarser first. If the cloth has been used twenty or thirty times, replace it: coffee oils block the weave and nothing cleans them out.
How do I look after the cloth filter?
Rinse it thoroughly, then store it submerged in water in a sealed jar in the fridge. Dried out, it goes rancid and taints everything. Boil it in clean water occasionally and replace it every couple of months.
Is a siphon just a gimmick?
No. The constant brew temperature is a genuine technical advantage and the cup is distinctive: clean, aromatic and fuller-bodied than paper pour over. It is slow and fragile, which is the real reason it is not more common.
Can I use cold water?
Yes, it just takes five minutes longer for the burner to get there, and the glass is under heat the whole time. Preboiled water is kinder to the brewer and the brew.