Fellow Prismo
How to use the Fellow Prismo, the AeroPress cap with a pressure-actuated valve for espresso-style shots: a typical recipe, what it fits and how to dial it in.
Contents
- Method
- The short version
- How does the Prismo work?
- How much coffee and water should I use?
- What grind size should I use?
- How do you use the Prismo, step by step?
- How do I dial in a Prismo shot?
- Which AeroPress does it fit?
- Prismo vs other ways to get a stronger shot
- How do you clean it?
- Prismo vs other methods
- Words in this guide
- Questions & answers
What is the Fellow Prismo?
The Fellow Prismo is a replacement cap for the AeroPress with a pressure-actuated valve and a metal filter. The valve stops coffee dripping through until you press, so you can brew a short, strong, espresso-style shot. Fellow's own recipe is 20 g of fine, fresh espresso-blend coffee and 50 g of boiling water, stirred, left until the one-minute mark, then pressed firmly. It isn't true espresso.
At a glance
- Ratio
- 1:2.5
- 20 g : 50 g
- Grind
- Fine
- Water
- Boiling (100°C)
- Difficulty
- Intermediate
- Origin
- United States
Method
Fit the Prismo
Attach the Prismo, with its metal filter, to the bottom of the AeroPress chamber in place of the standard cap, and stand it on your scale. The valve stops anything dripping out.
Add the coffee
Add 20 g of finely ground coffee. Fellow recommends a fresh espresso blend, less than 10 days from roasting.
Add water20 s
Start a timer and slowly pour in 50 g of boiling water, taking 10 to 20 seconds.
Stir30 s
Stir for 20 to 30 seconds so all the coffee is wet.
Wait for the minute
Let it sit until the timer reaches 60 seconds, then lift the AeroPress onto your cup and put the plunger in.
Press firmly
Use a strong, quick initial press, then hold steady pressure. It should take 10 to 20 seconds to press through. If the plunger moves very quickly, grind finer next time.
The Fellow Prismo is a replacement cap for the AeroPress, made by Fellow. It has a pressure-actuated valve and a fine metal filter. The valve stays shut while the coffee steeps, so nothing drips through, and it only opens when you press. Its smaller opening also lets pressure build as you plunge. The result is a short, strong, espresso-style shot: not true espresso, but the closest an AeroPress gets. Here’s how to use one.
The short version
- A cap for the AeroPress with a valve and a metal filter.
- No drip-through: the valve opens only when you press.
- Fellow’s recipe: 20 g of fine, fresh espresso-blend coffee to 50 g of boiling water.
- Stir, wait until the one-minute mark, press firmly for 10 to 20 seconds.
- Espresso-style, not espresso: an AeroPress can’t reach espresso’s 9 bar.
How does the Prismo work?
The Prismo screws onto the AeroPress chamber in place of the standard filter cap. Its valve stays closed until there’s pressure behind it, so the coffee and water stay together while they steep. Its opening is smaller than the standard cap’s, so as you press, pressure builds before the valve lets the coffee through. One reviewer describes it as stepping down the aperture of the AeroPress to increase the pressure. You get a more concentrated, more intense shot than a standard AeroPress, but not espresso as a café makes it.
How much coffee and water should I use?
Fellow publishes a standard espresso-style recipe:
| Fellow’s recipe | |
|---|---|
| Coffee | 20 g, ground fine, a fresh espresso blend |
| Water | 50 g, boiling (100°C / 212°F) |
| Pour | Slowly, over 10 to 20 seconds |
| Stir | 20 to 30 seconds |
| Press | At 60 seconds, taking 10 to 20 seconds |
Fellow recommends coffee less than 10 days from roasting, and warns that water even a little under boiling, around 93°C (200°F), can give a sour shot. Other published recipes use a little more water, up to about 70 g, and some brew inverted and dilute the shot afterwards.
What grind size should I use?
Fine, close to an espresso grind. Fellow’s test is the press: it should take 10 to 20 seconds. If the plunger moves very quickly, grind finer. If it’s very hard to press, grind a little coarser.
How do you use the Prismo, step by step?
- Fit the Prismo with its metal filter to the bottom of the AeroPress, and stand it on your scale. The valve stops it dripping.
- Add 20 g of fine coffee.
- Start a timer and pour in 50 g of boiling water slowly, over 10 to 20 seconds.
- Stir for 20 to 30 seconds.
- At 60 seconds, lift the AeroPress onto your cup and put the plunger in.
- Press with a strong, quick start, then hold steady pressure for 10 to 20 seconds.
Brew mode on this page times the stir and the wait for you.
How do I dial in a Prismo shot?
- Plunger moves very quickly, or the shot is thin: grind finer (Fellow).
- Sour: check the water is boiling (Fellow). Boomtown Coffee’s guide also suggests waiting a little longer before you press.
- Bitter: Boomtown suggests pressing a little sooner.
- Little or no crema: Fellow links this to stale coffee, light roasts, too little stirring or too coarse a grind.
- Hard to press: grind coarser; don’t force it.
Drink the shot as it is, top it up with hot water for an Americano-style cup, or add milk.
Which AeroPress does it fit?
Fellow says the Prismo fits the standard AeroPress and the AeroPress Clear. It does not fit the AeroPress XL, the AeroPress Go, or AeroPress models made between 2005 and 2009. Its filter is etched stainless steel with 150-micron holes.
Prismo vs other ways to get a stronger shot
| Fellow Prismo | AeroPress Flow Control | Moka pot | |
|---|---|---|---|
| Made by | Fellow | AeroPress | Many makers |
| Filter | Metal, included | Paper or metal | Metal basket |
| Valve | Pressure-actuated | Pressure-actuated | None (a safety valve only) |
| Aimed at | Espresso-style shots | Longer steeps without drip | Strong stovetop coffee |
How do you clean it?
Push out the puck and rinse the cap and filter. Fellow’s tip: attach the Prismo to the AeroPress, fill it with hot water and a couple of drops of washing-up liquid, and press it through, then rinse.
General guidance only. Press steadily rather than forcing it, keep the AeroPress on a sturdy cup, and follow the instructions from Fellow and AeroPress.
Prismo vs other methods
- AeroPress: the brewer the Prismo fits.
- AeroPress Flow Control: AeroPress’s own no-drip cap.
- Portable espresso: hand-powered makers that reach true espresso pressure.
- Espresso: the real thing, at about 9 bar.
Explore every hybrid brewer in the hybrid chapter.
What you’ll need
Words in this guide
- Metal filter
- A metal filter is a fine stainless-steel mesh that holds back coffee grounds, as used in a French press plunger and some reusable pour-over filters.
- Steeping
- Steeping is leaving ground coffee to sit in water so its flavour dissolves out, as in a French press or cold brew.
- Crema
- Crema is the golden-brown foam on top of an espresso.
- Roast level
- Roast level describes how long and how hot coffee beans were roasted, usually labelled light, medium or dark.
- Agitation
- Agitation is any movement of the coffee and water during brewing, such as stirring, swirling or a turbulent pour.
- Safety valve
- A safety valve is a small pressure-release valve on the side of a moka pot base.
Questions & answers
Does the Fellow Prismo make real espresso?
No. It makes a short, strong, espresso-style shot. An AeroPress can't reach the roughly 9 bar of an espresso machine, so the shot is concentrated but different. Fellow says it can make crema; reviewers found the crema inconsistent.
Which AeroPress does the Prismo fit?
Fellow says it fits the standard AeroPress and the AeroPress Clear, but not the AeroPress XL, the AeroPress Go, or AeroPress models made between 2005 and 2009.
What's a good Prismo recipe?
Fellow's standard recipe is 20 g of fine, fresh espresso-blend coffee and 50 g of boiling water. Pour over 10 to 20 seconds, stir for 20 to 30 seconds, then press at the one-minute mark, taking 10 to 20 seconds. Top it up with hot water for an Americano-style drink, or with milk.
How do I fix a sour or bitter Prismo shot?
Fellow says water even a little under boiling, around 93°C (200°F), can make the shot sour, so use it straight off the boil. If the plunger goes down very quickly, grind finer. Boomtown Coffee's guide suggests waiting longer before you press if it's sour, and pressing sooner if it's bitter.
Prismo vs AeroPress Flow Control?
Both are caps with a valve that stops drip-through. The Prismo, from Fellow, comes with a metal filter and is aimed at espresso-style shots; the Flow Control cap is AeroPress's own, used with their paper filters.
Sources
- Prismo. Fellow
- How to dial in your Prismo AeroPress attachment. Fellow
- Fellow Prismo guide. Boomtown Coffee
- AeroPress espresso recipe with Prismo attachment. Clarity Coffee
- I added the Fellow Prismo to my AeroPress. Tom's Guide
- Fellow Prismo: how to make espresso with an AeroPress. Handsome Wade
General guidance only. Not medical, food-safety or professional advice. Always follow your equipment's own instructions.